RISK FACTORS

Investing in our common stock involves a high degree of risk. You should carefully consider the risks described below, as well as the other information in this prospectus, including our financial statements and the related notes and “Management’s Discussion and Analysis of Results of Operations and Financial Condition,” before deciding whether to invest in our common stock. The occurrence of any of the events or developments described below could harm our business, financial condition, results of operations and growth prospects. In such an event, the market price of our common stock could decline, and you may lose all or part of your investment. Additional risks and uncertainties not presently known to us or that we currently deem immaterial also may impair our business operations.

Risks Related to Our Limited Operating History and Financial Condition

We have a limited operating history and have incurred significant losses since our inception and we anticipate that we will continue to incur losses for the foreseeable future. We are currently developing three compounds for six product approvals in each of the United States and Europe and have no commercial sales, which, together with our limited operating history, makes it difficult to assess our future viability.

We are a development-stage biopharmaceutical company in the pet therapeutics industry with a limited operating history. Biopharmaceutical product development in the pet therapeutics industry is a highly speculative undertaking and involves a substantial degree of risk. To date, we have focused primarily on developing our licensed compounds, AT-001, AT-002 and AT-003, for six product approvals in cats and dogs in each of the United States and Europe. We are not profitable and have incurred losses in each year since our inception in December 2010. We have a limited operating history upon which you can evaluate our business and prospects. In addition, as an early stage company, we have limited experience and have not yet demonstrated an ability to successfully overcome many of the risks and uncertainties frequently encountered by companies in new and rapidly evolving fields, particularly in the biopharmaceutical industry. We have not generated any revenue from product sales to date. We continue to incur significant research and development and other expenses related to our ongoing operations. Our net loss for the three months ended March 31, 2013 was $3.3 million and for the years ended December 31, 2011 and 2012 was $3.5 million and $11.6 million, respectively. As of March 31, 2013, we had a deficit accumulated during development stage of $25.5 million and we had $25.7 million in cash, cash equivalents and short-term investments. We expect to continue to incur losses for the foreseeable future, and we expect these losses to increase as we continue our development of, and seek regulatory approvals for, our product candidates and begin to commercialize them if they are approved by the U.S. Food and Drug Administration’s Center for Veterinary Medicine, or CVM. Even if we achieve profitability in the future, we may not be able to sustain profitability in subsequent periods. Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ equity and working capital.

We may require substantial additional financing to achieve our goals, and a failure to obtain this necessary capital when needed on acceptable terms, or at all, could force us to delay, limit, reduce or terminate our product portfolio expansion, product development, other operations or commercialization efforts.

Since our inception, nearly all of our resources have been dedicated to the in-licensing and research and development of our current product candidates. Completing the development and obtaining regulatory approval of our product candidates will require substantial funds. We also have an active in-licensing effort focused on identifying human therapeutics for development and commercialization as pet therapeutics. We believe that we will continue to expend substantial resources for the foreseeable future for the development of our current product candidates and in-licensing and research and development of any other product candidates we may choose to pursue. These expenditures will include costs associated with identifying potential product candidates, licensing payments, conducting target animal studies, completing other research and development, obtaining regulatory approvals and manufacturing and supply, as well as marketing and selling any products approved for sale. In

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addition, other unanticipated costs may arise. Because the outcome of any target animal study is uncertain, we cannot reasonably estimate the actual amounts necessary to successfully complete the development and commercialization of any of our current or future product candidates.

We believe that the net proceeds from this offering, together with our existing cash and cash equivalents and existing credit facility will allow us to fund our operating plan through at least the next 24 months. However, our operating plan may change as a result of many factors currently unknown to us, and we may need to seek additional funds sooner than planned through public or private equity or debt financings or other sources, such as strategic collaborations. Such financing may result in dilution to stockholders, imposition of debt covenants and repayment obligations, or other restrictions that may affect our business. In addition, we may seek additional capital due to favorable market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans.

Our future capital requirements depend on many factors, including, but not limited to:

Additional funds may not be available when we need them on terms that are acceptable to us, or at all. If adequate funds are not available to us on a timely basis, we may be required to delay, limit, reduce or terminate:

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Risks Related to Our Business

We are substantially dependent on the success of our current compounds, AT-001, AT-002 and AT-003, which are currently our only product candidates and are still in development.

We currently have no products approved for commercial distribution. To date, we have invested nearly all of our efforts and financial resources in the in-licensing, research and development of AT-001, AT-002 and AT-003, which are currently our only product candidates and are still in development.

Our near-term prospects, including our ability to finance our company and to enter into strategic collaborations and generate revenue, will depend heavily on the successful development and commercialization of our current and future product candidates. The development and commercial success of our current product candidates will depend on a number of factors, including the following:

Many of these factors are beyond our control. Accordingly, we cannot assure you that we will ever be able to generate revenue through the sale of our product candidates. If we are not successful in commercializing one or more of our product candidates, or are significantly delayed in doing so, our business will be materially harmed and the value of your investment could substantially decline.

If we are not successful in identifying, licensing, developing and commercializing additional product candidates, our ability to expand our business and achieve our strategic objectives would be impaired.

Although a substantial amount of our effort will focus on the continued development and potential approval of our current product candidates, a key element of our strategy is to identify, license, develop and commercialize a portfolio of products to serve the pet therapeutics market. We derive potential pet therapeutic product candidates from molecules and compounds discovered or developed as part of human biopharmaceutical research. We expect to enter into license arrangements with third parties to provide us with rights to human health compounds for purposes of our business. Such agreements are typically complex and require time to negotiate and implement. If we

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enter into these arrangements, we may not be able to maintain these relationships or establish new ones in the future on acceptable terms or at all. If we are unable to access human health-generated molecules and compounds to conduct research and development on cost-effective terms, our ability to develop new products could be limited. In some instances, human biopharmaceutical companies may be unwilling to license us their products or compounds for development as pet therapeutics because of perceived regulatory and commercial risks, including the risk that the FDA could delay or halt an ongoing human development trial if the same compound, when studied in animals, produces an unexplained adverse event or death, and the risk that, if the same compound is developed for humans and pets, and the human version is priced significantly higher than the pet version, which is usually the case, human patients would attempt to use the cheaper animal version of the drug. Even if we successfully identify and license potential product candidates, we may still fail to yield product candidates for development and commercialization for many reasons, including the following:

If we fail to develop and successfully commercialize other product candidates, our business and future prospects may be harmed and our business will be more vulnerable to any problems that we encounter in developing and commercializing our current and future product candidates.

We may be unable to obtain regulatory approval for our existing or future product candidates under applicable regulatory requirements. The denial or delay of any such approval would delay commercialization efforts and adversely impact our potential to generate revenue, our business and our results of operations.

Our product candidates are in various stages of development, and our business currently depends entirely on their successful development, regulatory approval and commercialization. We currently have no drug products approved for sale, and we may never obtain regulatory approval to commercialize any of our current or future product candidates. The research, testing, manufacturing, labeling, approval, sale, marketing and distribution of pet therapeutics products are subject to extensive regulation by the CVM, the EMA and other regulatory authorities in the United States and other countries, whose regulations differ from country to country. We are not permitted to market our products in the United States until we receive approval of a New Animal Drug Application, or NADA, from the CVM or in Europe until we receive approval from the EMA.

To gain approval to market a pet therapeutic for a particular species of pet, we must provide the CVM and foreign regulatory authorities with data from animal safety and effectiveness studies that adequately demonstrate the safety and efficacy of that product in the target animal for the intended indication applied for in the NADA or other regulatory filing. The development of pet therapeutics in a target animal is a lengthy, expensive and uncertain process, and delay or failure can occur at any stage of any of our development efforts. Success in prior target animal studies or in the treatment of human beings with a product candidate does not ensure that our target animal studies will be successful and the results of development efforts by other parties may not be indicative of the results of our target animal studies and other development efforts.

The CVM or any foreign regulatory bodies can delay, limit or deny approval of any of our product candidates for many reasons, including:

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Even if we receive approval of an NADA or foreign regulatory filing for our product candidates, the CVM or the applicable foreign regulatory body may approve our product candidates for a more limited indication than we originally requested, and the CVM may not approve the labeling that we believe is necessary or desirable for the successful commercialization of our product candidates. Any delay in obtaining, or inability to obtain, applicable regulatory approval would delay or prevent commercialization of our product candidates and would materially adversely impact our business and prospects.

Even if our current or future product candidates obtain regulatory approval, they may never achieve market acceptance or commercial success.

Even if we obtain CVM or other regulatory approvals, our current or future product candidates may not achieve market acceptance among veterinarians and pet owners, and may not be commercially successful. Market acceptance of any of our current or future product candidates for which we receive approval depends on a number of factors, including:

Any failure by our product candidates that obtain regulatory approval to achieve market acceptance or commercial success would adversely affect our financial results.

Development of pet therapeutics involves an expensive and lengthy process with an uncertain outcome, and results of earlier studies may not be predictive of future study results.

Development of pet therapeutics is expensive and can take many years to complete, and its outcome is inherently uncertain. Furthermore, we rely on contract research organizations, or CROs, and other third parties to ensure the proper and timely conduct of our studies and development efforts and, while we have agreements governing their committed activities, we have limited influence over their actual performance. Failure can occur at any time during the development process. The results of our initial development efforts and previous studies conducted by third parties may not be predictive of and do not ensure that our target animal studies and other development efforts will demonstrate similar results. Product candidates in our studies may fail to show the desired safety and efficacy

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despite showing such results in initial data or previous human or animal studies conducted by other parties. Even if our studies and other development efforts are completed, the results may not be sufficient to obtain regulatory approval for our product candidates.

Once our target animal studies commence, we may experience delays in such studies and other development efforts and we do not know whether planned studies will begin on time, need to be redesigned or be completed on schedule, if at all. Pet therapeutics studies can be delayed or aborted for a variety of reasons, including delay or failure to:

If we experience delays in the completion of, or termination of, any development efforts for our product candidates, the commercial prospects of our product candidates will be harmed, and our ability to generate product revenues from any of these product candidates will be delayed. In addition, any delays in completing our development efforts will increase our costs, slow down our product candidate development and approval process and jeopardize our ability to commence product sales and generate revenues. Any of these occurrences may harm our business, financial condition and prospects significantly. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of our development efforts may also ultimately lead to the denial of regulatory approval of our product candidates.

Our product candidates, if approved, will face significant competition and our failure to effectively compete may prevent us from achieving significant market penetration.

The development and commercialization of pet therapeutics is highly competitive, and we expect considerable competition from major pharmaceutical, biotechnology and specialty animal health medicines companies. As a result, there are and will likely continue to be extensive research and substantial financial resources invested in the discovery and development of new pet therapeutics. Our potential competitors include large animal health companies, such as Merck Animal Health, the animal health division of Merck & Co., Inc.; Merial, the animal health division of Sanofi S.A.; Elanco, the animal health division of Eli Lilly and Company; Bayer Animal Health, the animal health division of Bayer AG; Novartis Animal Health, the animal health division of Novartis AG; Boehringer Ingelheim Animal Health, the animal health division of Boehringer Ingelheim GmbH; and Zoetis, Inc. We also compete against several animal health companies in Europe, such as the Virbac Group, Ceva Animal Health and Dechra Pharmaceuticals PLC. We are also aware of several smaller early stage companies that are developing products for use in the pet therapeutics market.

At the product level, we will face competition for AT-001 from Rimadyl, Deramaxx, Previcox and Metacam. We are not aware of any direct competitor for AT-002. We expect AT-003 will compete primarily with the non-steroidal anti-inflammatory drugs from the class of cyclooxygenase inhibitors and injectable anesthetics, such as bupivacaine, which is not approved for non-human use but is widely used by veterinarians. We may also face competition from generic medicines and products approved for use in humans that are used off label for pets.

We are an early-stage company with a limited history of operations and many of our competitors have substantially more resources than we do, including both financial and technical. In addition, many of our competitors have more experience than we have in the development, manufacture, regulation and worldwide commercialization of animal health medicines, including pet therapeutics. We are also competing with academic institutions, governmental agencies and private organizations that are conducting research in the field of animal health medicines.

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If we fail to attract and keep senior management and key scientific personnel, we may be unable to successfully develop any of our current or future product candidates, conduct our in-licensing and development efforts and commercialize any of our current or future product candidates.

Our success depends in part on our continued ability to attract, retain and motivate highly qualified management and scientific personnel. We are highly dependent upon our senior management, particularly Steven St. Peter, M.D., our President and Chief Executive Officer, Ernst Heinen, Ph.D., D.V.M., our Head of Drug Evaluation and Development, Louise A. Mawhinney, our Chief Financial Officer, Linda Rhodes, V.M.D, Ph.D., our Chief Scientific Officer, and Julia Stephanus, our Chief Commercial Officer, as well as our senior scientists and other members of our senior management team. The loss of services of any of these individuals could delay or prevent the successful development of our current or future product pipeline, completion of our planned development efforts or the commercialization of our product candidates. Although we have entered into employment agreements with Dr. St. Peter, Dr. Heinen, Ms. Mawhinney, Dr. Rhodes and Ms. Stephanus, these agreements do not provide for a fixed term of service.

Although we have not historically experienced unique difficulties attracting and retaining qualified employees, we could experience such problems in the future. For example, competition for qualified personnel in the animal health fields is intense due to the limited number of individuals who possess the skills and experience required by our industry. We will need to hire additional personnel as we expand our development and commercial activities. We may not be able to attract and retain quality personnel on acceptable terms, or at all. In addition, to the extent we hire personnel from competitors, we may be subject to allegations that they have been improperly solicited or that they have divulged proprietary or other confidential information, or that their former employers own their research output.

We rely completely on third-party manufacturers to manufacture the supplies for the development of our current product candidates and we intend to rely on third-party manufacturers to produce commercial quantities of any approved drug candidate.

We do not currently have, nor do we plan to acquire, the infrastructure or capability internally to manufacture the formulated drug for use in the conduct of our target animal studies. We also lack the resources and the capability to manufacture any of our product candidates on a scale necessary for commercialization. We will need to identify contract manufacturers to provide commercial supplies of the formulated drugs for AT-001 and AT-002. For AT-003, we have entered into a commercial supply agreement with Pacira Pharmaceuticals, Inc., or Pacira. Under this agreement, Pacira will provide us with finished drug product in vials, without final labeling and packaging, for which we are responsible. Pacira may terminate this supply agreement if we fail to make an undisputed payment, if we breach a material provision of the agreement, or if Pacira ceases manufacture of the product. Pacira also has the unilateral right to change its manufacturing process for the product, and if we cannot reach agreement on the terms of continued supply of AT-003 meeting current specifications and Pacira decides that it is no longer commercially reasonable to supply us with product meeting such specifications, then Pacira may terminate this supply agreement. If this supply agreement terminates for any reason, we may be unable to arrange for alternative supply of AT-003. We cannot assure you that we will be able to identify an alternate contract manufacturer for AT-003 in a timely manner on commercially reasonable terms, or at all. Additionally, we may be unable to identify and reach agreement with a contract manufacturer for AT-001 and AT-002 in a timely manner on commercially reasonable terms, or at all. Any delay in our ability to identify and contract with these third-party contract manufacturers on commercially reasonable terms, or at all, would have an adverse impact upon our business.

In July 2012, we entered into an API development agreement with RaQualia Pharma Inc., or RaQualia, pursuant to which we agreed to develop a manufacturing process for AT-001 that is cGMP compliant. We intend to fulfill this obligation through a contract manufacturer, Cambridge Major Laboratories, Inc., or CML, whom we engaged in August 2011 to develop the manufacturing process for AT-001. If our arrangement with CML terminates for any reason, we may not be able to identify an alternate contract manufacturer to develop a cGMP compliant manufacturing process for AT-001 in a timely manner, on commercially reasonable terms, or at all. Any delay in

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our ability to identify and contract with such an alternate contract manufacturer in a timely manner, on commercially reasonable terms, or at all, would have an adverse impact upon our business, including our relationship with RaQualia.

The facilities used by our contract manufacturers to manufacture the active pharmaceutical ingredients and formulated drugs may be subject to inspections by the CVM that will be conducted after we submit our NADA to the CVM, and approval by the CVM. We do not control the manufacturing processes used by, and we are completely dependent on, our contract manufacturers to comply with cGMP for the manufacture of both active pharmaceutical ingredients and finished drug products. If our contract manufacturers cannot successfully manufacture material that conforms to our specifications and is made in compliance with the strict regulatory requirements of the CVM or other regulatory authorities, they will not be able to secure and/or maintain regulatory approval for their manufacturing facilities. In addition, we have no control over the ability of our contract manufacturers to maintain adequate quality control and quality assurance practices and to engage qualified personnel. If the CVM or a comparable foreign regulatory authority does not approve our contract manufacturers’ facilities used for the manufacture of our product candidates, or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would adversely impact our ability to develop, obtain regulatory approval for or market our product candidates, if approved.

Furthermore, we and our third-party contractors are continuing to refine and improve the manufacturing process for our product candidates, certain aspects of which are complex and unique. We may encounter difficulties with new or existing manufacturing processes, particularly if we seek to increase our manufacturing capacity significantly to support commercialization of our product candidates, if approved. Our reliance on contract manufacturers also requires us to provide trade secrets or other proprietary information to others engaged to make our drug products, increasing the possibility that our trade secrets or other proprietary information may be disclosed or misappropriated.

The commercialization of any of our product candidates could be stopped, delayed or made less profitable if third-party manufacturers fail to provide us with sufficient quantities of drug product or fail to do so at acceptable quality levels or prices and in a timely manner.

To manufacture our product candidates in the quantities that we believe would be required to meet anticipated market demand, our third-party manufacturers may need to increase manufacturing capacity, which could involve significant challenges and may require additional regulatory approvals. In addition, the development of commercial-scale manufacturing capabilities may require us and our third-party manufacturers to invest substantial additional funds and hire and retain technical personnel who have the necessary manufacturing experience. Neither we nor our third-party manufacturers may successfully complete any manufacturing scale-up activities required to increase existing manufacturing capabilities in a timely manner, or at all. Under our exclusive supply agreement for AT-003, Pacira has the obligation to provide only a mid to high double-digit percentage of our requested commercial quantity of bulk finished drug product during the first six calendar quarters following commercial launch of AT-003.

The raw materials used to manufacture our products are generally readily available and can be obtained from multiple suppliers in commercial quantities. However, we rely on our contract manufacturers to obtain any raw materials necessary to manufacture our products, and we do not have any control over the process or timing of the acquisition of these materials. Furthermore, if there is a disruption to our or our third-party manufacturers’ relevant operations, we will have no other means of producing our product candidates until they restore the affected facilities or we or they procure alternative manufacturing facilities or raw materials. Additionally, any damage to or destruction of our third-party manufacturers’ facilities or equipment may significantly impair our ability to manufacture product candidates on a timely basis.

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We currently rely on third parties to conduct all our target animal studies and certain other development efforts. If these third parties do not successfully carry out their contractual duties or meet expected deadlines, we may be unable to obtain regulatory approval for or commercialize our current or future product candidates.

We currently do not conduct our target animal studies, and we rely on CROs to conduct these studies. The third parties with whom we contract for the execution of our studies play a significant role in the conduct of these studies and the subsequent collection and analysis of data. However, these third parties are not our employees, and except for contractual duties and obligations, we have limited ability to control the amount or timing of resources that they devote to our programs. Although we rely on these third parties to conduct our studies, we remain responsible for ensuring that each of our studies is conducted in accordance with the development plan and protocol. Moreover, the CVM and foreign regulatory authorities require us to comply with regulations and standards, commonly referred to as current good clinical practices, or cGCPs, or good laboratory practices, or GLPs, for conducting, monitoring, recording and reporting the results of our studies to ensure that the data and results are scientifically credible and accurate.

In addition, the execution of target animal studies and the subsequent compilation and analysis of the data produced requires coordination among various parties. In order for these functions to be carried out effectively and efficiently, it is imperative that these parties communicate and coordinate with one another. Moreover, these third parties may also have relationships with other commercial entities, some of which may compete with us. Many of our agreements with these third parties may be terminated by these third parties upon as little as 30 days prior written notice of a material breach by us that is not cured within 30 days. Many of these agreements may also be terminated by such third parties under certain other circumstances, including our insolvency or our failure to comply with applicable laws. In general, these agreements require such third parties to reasonably cooperate with us at our expense for an orderly winding down of services of such third parties under the agreements. If the third parties conducting our target animal studies do not perform their contractual duties or obligations, experience work stoppages, do not meet expected deadlines, terminate their agreements with us or need to be replaced, or if the quality or accuracy of the data they obtain is compromised due to the failure to adhere to our development protocols or cGCPs, or for any other reason, we may need to enter into new arrangements with alternative third parties, which could be difficult and costly, and our target animal studies may be extended, delayed or terminated or may need to be repeated. If any of the foregoing were to occur, the regulatory approval for and commercialization of the product candidate being tested in such studies may be delayed or require us to utilize additional resources.

Our ability to market our product candidates in the United States, if approved, will be limited to use for the treatment of the indications for which they are approved, and if we want to expand the indications for which we may market our product candidates, we will need to obtain additional CVM approvals, which may not be granted.

We expect to seek CVM approval in the United States for AT-001 for the treatment of pain and inflammation associated with osteoarthritis in dogs and for pain management in cats, AT-002 for the treatment of inappetence in cats and dogs, and AT-003 for the treatment of post-operative pain in cats and dogs. If our product candidates are approved, the CVM will restrict our ability to market or advertise them for the treatment of indications other than the indications for which they are approved, which could limit their adoption by veterinarian and pet owners. We may attempt to develop, promote and commercialize new treatment indications and protocols for our product candidates in the future, but we cannot predict when or if we will receive the approvals required to do so. In addition, we would be required to conduct additional target animal studies to support our applications, which would utilize additional resources and may produce results that do not result in CVM approvals. If we do not obtain additional CVM approvals, our ability to expand our business in the United States will be limited.

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We currently have no sales organization. If we are unable to establish sales capabilities on our own or through third parties, we may not be able to market and sell our current or future product candidates, if approved, or generate product revenue.

We currently do not have a sales organization. In order to commercialize any of our current or future product candidates in the United States and any jurisdictions outside the United States, we must build our marketing, sales, distribution, managerial and other non-technical capabilities or make arrangements with third parties to perform these services, and we may not be successful in doing so. If our current or any future product candidates receive regulatory approval, we expect to establish a direct sales organization in the United States, complemented by distributors, to commercialize our product candidates, which will be expensive and time-consuming. Outside of the United States we intend to partner with companies with an established commercial presence to market our products in those locations. If we are unable to enter into such arrangements on acceptable terms or at all, we may not be able to successfully commercialize our current product candidates or any future product candidates that receive regulatory approval. We have no prior experience in the marketing, sale and distribution of pet therapeutics and there are significant risks involved in building and managing a sales organization, including our ability to hire, retain and motivate qualified individuals, generate sufficient sales leads, provide adequate training to sales and marketing personnel, and effectively oversee a geographically dispersed sales and marketing team. Any failure or delay in the development of our internal sales, marketing and distribution capabilities would adversely impact the commercialization of these products. If we are not successful in commercializing any of our current or future product candidates, either on our own or through collaborations with one or more distributors, our future product revenue will suffer and we would incur significant additional losses.

We will need to increase the size of our organization, and we may experience difficulties in managing growth.

As of March 31, 2013, we had 16 full-time employees. We will need to continue to expand our managerial, operational, financial and other resources in order to manage our operations and target animal studies, continue our development activities and commercialize any of our current or future product candidates. Our management and personnel, systems and facilities currently in place may not be adequate to support this future growth. Our need to effectively execute our growth strategy requires that we:

We will incur significant costs as a result of operating as a public company, and our management will devote substantial time to new compliance initiatives.

As a privately-held company, we were not required to comply with certain corporate governance and financial reporting practices and policies required of a publicly-traded company. As a publicly-traded company, we will incur significant legal, accounting and other expenses that we were not required to incur in the recent past, particularly after we are no longer an “emerging growth company” as defined under the Jumpstart Our Business Start-ups Act of 2012, or the JOBS Act. In addition, new and changing laws, regulations and standards relating to corporate governance and public disclosure, including the Dodd-Frank Wall Street Reform and Consumer Protection Act and the rules and regulations promulgated and to be promulgated thereunder, as well as under the Sarbanes-Oxley Act, the JOBS Act, and the rules and regulations of the U.S. Securities and Exchange Commission, or SEC, and The NASDAQ Global Market, have created uncertainty for public companies and increased our costs and time that our board of directors and management must devote to complying with these rules and regulations. We expect these rules and regulations to increase our legal and financial compliance costs and lead to a diversion of management time and attention from revenue generating activities.

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Furthermore, the need to establish the corporate infrastructure demanded of a public company may divert management’s attention from implementing our growth strategy, which could prevent us from improving our business, results of operations and financial condition. We have made, and will continue to make, changes to our internal controls and procedures for financial reporting and accounting systems to meet our reporting obligations as a publicly-traded company. However, the measures we take may not be sufficient to satisfy our obligations as a publicly-traded company.

For as long as we remain an “emerging growth company” as defined in the JOBS Act, we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not “emerging growth companies.” These exceptions provide for, but are not limited to, relief from the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act, less extensive disclosure obligations regarding executive compensation in our periodic reports and proxy statements, exemptions from the requirements to hold a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved and an extended transition period for complying with new or revised accounting standards. We may take advantage of these reporting exemptions until we are no longer an “emerging growth company.” We may remain an “emerging growth company” for up to five years. See “Prospectus Summary—Implications of Being an Emerging Growth Company.” To the extent we are no longer eligible to use exemptions from various reporting requirements under the JOBS Act, we may be unable to realize our anticipated cost savings from those exemptions.

Our internal control over financial reporting does not currently meet the standards required by Section 404 of the Sarbanes-Oxley Act, and failure to achieve and maintain effective internal control over financial reporting in accordance with Section 404 of the Sarbanes-Oxley Act could have a material adverse effect on our business and share price.

As a privately-held company, we were not required to evaluate our internal control over financial reporting in a manner that meets the standards of publicly-traded companies required by Section 404 of the Sarbanes-Oxley Act, or Section 404. We anticipate being required to meet these standards in the course of preparing our financial statements as of and for the year ended December 31, 2014, and our management will be required to report on the effectiveness of our internal control over financial reporting for such year. Additionally, under the recently enacted JOBS Act, our independent registered public accounting firm will not be required to attest to the effectiveness of our internal control over financial reporting pursuant to Section 404 of the Sarbanes-Oxley Act until we are no longer an “emerging growth company.” The rules governing the standards that must be met for our management to assess our internal control over financial reporting are complex and require significant documentation, testing and possible remediation.

A material weakness in internal control was identified in connection with the preparation of our financial statements and the audit of our financial results for 2011. We determined that we had a material weakness relating to accounting for complex transactions and cut-off of expenses. During 2012, we added personnel to our accounting staff with appropriate levels of experience to remediate the aforementioned material weakness. As of December 31, 2012, we determined the material weakness had been remediated as a result of the actions taken above and the resulting improvements in our internal controls.

In connection with the implementation of the necessary procedures and practices related to internal control over financial reporting, we may identify deficiencies that we may not be able to remediate in time to meet the deadline imposed by the Sarbanes-Oxley Act for compliance with the requirements of Section 404. In addition, we may encounter problems or delays in completing the implementation of any requested improvements and receiving a favorable attestation in connection with the attestation provided by our independent registered public accounting firm. We will be unable to issue securities in the public markets through the use of a shelf registration statement if we are not in compliance with Section 404. Furthermore, failure to achieve and maintain an effective internal control environment could have a material adverse effect on our business and share price and could limit our ability to report our financial results accurately and timely.

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Changes in distribution channels for pet therapeutics could negatively impact our market share, margins and distribution of our products.

In most markets, pet owners typically purchase their pet therapeutics directly from veterinarians. Pet owners increasingly could purchase pet therapeutics from sources other than veterinarians, such as Internet-based retailers, “big-box” retail stores or other over-the-counter distribution channels. This trend has been demonstrated by the significant shift away from the veterinarian distribution channel in the sale of parasiticides and vaccines in recent years. Pet owners also could decrease their reliance on, and visits to, veterinarians as they rely more on Internet-based animal health information. Because we expect to market our pet prescription products through the veterinarian distribution channel, any decrease in visits to veterinarians by pet owners could reduce our market share for such products and materially adversely affect our operating results and financial condition. In addition, pet owners may substitute human health products for pet therapeutics if human health products are deemed to be lower-cost alternatives.

Legislation has also been proposed in the United States, and may be proposed in the United States or abroad in the future, that could impact the distribution channels for our pet products. For example, such legislation may require veterinarians to provide pet owners with written prescriptions and disclosure that the pet owner may fill prescriptions through a third party, which may further reduce the number of pet owners who purchase their pet therapeutics directly from veterinarians. Such requirements may lead to increased use of generic alternatives to our products or the increased substitution of our products with other pet therapeutics or human health products if such other products are deemed to be lower-cost alternatives. Many states already have regulations requiring veterinarians to provide prescriptions to pet owners upon request and the American Veterinary Medical Association has long-standing policies in place to encourage this practice.

Over time, these and other competitive conditions may increase our reliance on Internet-based retailers, “big-box” retail stores or other over-the-counter distribution channels to sell our pet products. Any of these events could materially adversely affect our operating results and financial condition.

Consolidation of our customers could negatively affect the pricing of our products.

Veterinarians are our primary customers. In recent years, there has been a trend towards the concentration of veterinarians in large clinics and hospitals. If this trend towards consolidation continues, these customers could attempt to improve their profitability by leveraging their buying power to obtain favorable pricing. The resulting decrease in our prices could have a material adverse effect on our operating results and financial condition.

Our ability to use our net operating loss carryforwards to offset future taxable income may be subject to certain limitations.

As of December 31, 2012, we had net operating loss carryforwards, or NOLs, for federal and state income tax purposes of $1.1 million and $1.0 million, respectively, which may be available to offset our future taxable income, if any. Our federal NOLs begin to expire in 2031, and our state NOLs begin to expire in 2021. In general, under Section 382 of the Internal Revenue Code of 1986, as amended, or the Code, a corporation that undergoes an “ownership change” is subject to limitations on its ability to use its pre-change net operating loss carryforwards to offset future taxable income. If the Internal Revenue Service, or IRS, challenges our analysis that our existing NOLs will not expire before utilization due to previous ownership changes, or if we undergo an ownership change in connection with or after this public offering, our ability to use our NOLs could be limited by Section 382 of the Code. Future changes in our stock ownership, some of which are outside of our control, could result in an ownership change under Section 382 of the Code. Furthermore, our ability to use NOLs of companies that we may acquire in the future may be subject to limitations. For these reasons, we may not be able to use a material portion of the NOLs reflected on our balance sheet, even if we attain profitability.

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Generic products may be viewed as more cost-effective than our products.

We may face competition from products produced by other companies, including generic alternatives to any of our products. We will depend on patents to provide us with exclusive marketing rights for some of our products. As of April 30, 2013, we licensed approximately 27 issued patents or pending patent applications covering various composition of matter claims as well as methods of treatment. Our patent protection for these products extends for varying periods in accordance with the dates of filing or grant, the legal life of patents in countries in which patents are granted and the various terms and conditions of the respective agreement under which such patents are licensed. The key patent that we believe covers the crystalline form of the AT-001 compound expires on February 21, 2027, and the key patent that we believe covers certain methods of producing the AT-002 compound expires on February 1, 2020. Each of these patents may be eligible for an award of up to five years of patent term extension upon FDA approval of a commercial use of the corresponding product. The key patents that we believe cover certain compositions and methods of producing the AT-003 compound expire on September 18, 2018. The remainder of the patents in our current patent portfolio expire at various times between late 2013 and 2031, with a pending provisional application that upon issuance would expire in 2033. The protection afforded, which varies from country to country, is limited by the scope and applicable terms of our patents and the availability of legal remedies in the applicable country. As a result, we may face competition from lower-priced generic alternatives to many of our products. Generic competitors are becoming more aggressive in terms of pricing, and generic products are an increasing percentage of overall animal health sales in certain regions. In addition, private label products may compete with our products. If pet therapeutics customers increase their use of new or existing generic or private label products, our operating results and financial condition could be materially adversely affected.

Pet therapeutics are subject to unanticipated safety or efficacy concerns, which may harm our reputation.

Unanticipated safety or efficacy concerns can arise with respect to pet therapeutics, whether or not scientifically or clinically supported, leading to product recalls, withdrawals or suspended or declining sales, as well as product liability, and other claims. In addition, we depend on positive perceptions of the safety and quality of our products, and pet therapeutics generally, by our customers, veterinarians and end-users, and such concerns may harm our reputation. These concerns and the related harm to our reputation could materially adversely affect our operating results and financial condition, regardless of whether such reports are accurate.

Risks Related to Intellectual Property

We currently own one patent application, license the issued patents covering our product candidates and have limited rights to prosecute and enforce those licensed patents.

We currently own one patent application relating to our AT-002 product candidate that covers a method of treating inappetence using AT-002, and we cannot assure you that a patent based on this patent application will ever be issued. We do not own any patents or patent applications relating to AT-001 or AT-003. We have exclusive license agreements in the field of animal health with RaQualia, pursuant to which we license key intellectual property relating to AT-001 and AT-002, and with Pacira pursuant to which we license key intellectual property relating to AT-003. The patents and patent applications that we license cover various composition of matter claims as well as methods of treatment relating to our licensed patents. These patents are expected to expire at various times between late 2013 and 2031.

Under each of these agreements, RaQualia and Pacira retain ownership over the licensed patents and patent applications and retain control over the maintenance and prosecution of the licensed patents and patent applications. In the case of AT-003, we have no control over the manner in which Pacira chooses to maintain or prosecute its patent and patent applications and have no right to continue to prosecute any patents or patent applications that Pacira elects to abandon.

Although we have the right to enforce patents licensed from RaQualia against third-party infringement in the animal health field, we do not have the right to enforce patents licensed from Pacira against any third-party infringement, although we have certain limited rights to request our licensor to enforce such patents against infringement.

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If we cannot obtain ownership of issued patents covering our product candidates or we cannot prosecute or enforce licensed patents, our business, results of operations, financial condition and prospects would be adversely affected.

If we fail to comply with our obligations under our intellectual property licenses with third parties, we could lose license rights that are essential to our business.

We are party to license agreements with RaQualia and Pacira for our product candidates that are essential to our business. These license agreements impose various payment and performance obligations on us. If we fail to comply with these obligations, RaQualia or Pacira, as applicable, may have the right to terminate the relevant license agreement, in which event we would not be able to develop or commercialize AT-001, AT-002 and/or AT-003, as the case may be.

If we lose such license rights, our business, results of operations, financial condition and prospects would be adversely affected. We may enter into additional licenses in the future and if we fail to comply with obligations under those agreements, we could suffer adverse consequences.

We may not own any intellectual property rights we develop with respect to AT-003 or be able to share our licensed patent rights to AT-003 with future collaborators.

Our license agreement with Pacira contains certain obligations and restrictions on our ability to develop and commercialize AT-003. All of the intellectual property rights that we develop with respect to AT-003 will be owned by Pacira upon termination of this license agreement. If we wish to enter into any collaboration agreements relating to AT-003, Pacira has the right to approve all of our sublicensees. Furthermore, Pacira has a right of first negotiation for shared commercialization rights to AT-003 in the United States. These restrictions may impair or delay our ability to engage third parties to commercialize AT-003.

We may become subject to third parties’ claims alleging infringement of patents and proprietary rights or seeking to invalidate our patents or proprietary rights, which would be costly, time-consuming and, if successfully asserted against us, delay or prevent the development and commercialization of our current or future product candidates.

There has been substantial litigation and other proceedings regarding patent and other intellectual property rights in the field of pet therapeutics, as well as patent challenge proceedings, including interference and administrative law proceedings before the United States Patent and Trademark Office, or the U.S. PTO, and oppositions and other comparable proceedings in foreign jurisdictions. Recently, under U.S. patent reform laws, new procedures including inter partes review and post grant review have been implemented as of March 16, 2013. As stated below, the novel implementation of such reform laws presents uncertainty regarding the outcome of challenges to our patents in the future.

We cannot assure you that any of our current or future product candidates will not infringe existing or future patents. We may be unaware of patents that have already issued that a third party might assert are infringed by one of our current or future product candidates. Because patent applications can take many years to issue and may be confidential for eighteen months or more after filing, there may be applications now pending of which we are unaware and which may later result in issued patents that we may infringe by commercializing any of our current or future product candidates. In addition, third parties may obtain patents in the future and claim that use of our technologies infringes upon these patents. Moreover, we may face claims from non-practicing entities, which have no relevant product revenue and against whom our own patent portfolio may thus have no deterrent effect.

We may be subject to third-party claims in the future against us or our collaborators that would cause us to incur substantial expenses and, if successful against us, could cause us to pay substantial damages, including treble damages and attorney’s fees if we are found to be willfully infringing a third party’s patents. If a patent infringement suit were brought against us or our collaborators, we or they could be forced to stop or delay research,

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development, manufacturing or sales of the product candidate that is the subject of the suit. As a result of patent infringement claims, or in order to avoid potential claims, we or our collaborators may choose to seek, or be required to seek, a license from the third party and would most likely be required to pay license fees or royalties or both. These licenses may not be available on acceptable terms, or at all. Even if we or our collaborators were able to obtain a license, the rights may be nonexclusive, which would give our competitors access to the same intellectual property. Ultimately, we could be prevented from commercializing a product, or forced to redesign it, or to cease some aspect of our business operations if, as a result of actual or threatened patent infringement claims, we or our collaborators are unable to enter into licenses on acceptable terms. Even if we are successful in defending such claims, infringement and other intellectual property litigation can be expensive and time-consuming to litigate and divert management’s attention from our core business. Any of these events could harm our business significantly.

In addition to infringement claims against us, if third parties have prepared and filed patent applications in the United States that also claim technology to which we have rights, we may have to participate in interference proceedings in the U.S. PTO to determine the priority of invention. Third parties may also attempt to initiate reexamination, post grant review or inter partes review of our patents in the U.S. PTO. We may also become involved in similar opposition proceedings in the European Patent Office or similar offices in other jurisdictions regarding our intellectual property rights with respect to our products and technology.

If our efforts to protect the proprietary nature of the intellectual property related to any of our current or future product candidates are not adequate, we may not be able to compete effectively in our market.

We rely upon a combination of patents, trade secret protection, confidentiality and license agreements to protect the intellectual property related to our current product candidates and our development programs.

Composition-of-matter patents on the active pharmaceutical ingredient are generally considered to be the strongest form of intellectual property protection for pharmaceutical products, including pet therapeutics, as such patents provide protection without regard to any particular method of use or manufacture. We cannot be certain that the claims in our patent application covering composition-of-matter of our product candidates will be considered patentable by the U.S. PTO and courts in the United States, or by the patent offices and courts in foreign countries. Method-of-use patents protect the use of a product for the specified method. This type of patent does not prevent a competitor from making and marketing a product that is identical to our product for an indication that is outside the scope of the patented method. Moreover, even if competitors do not actively promote their product for our targeted indications, veterinarians may recommend that pet owners use these products off label, or pet owners may do so themselves. Although off-label use may infringe or contribute to the infringement of method-of-use patents, the practice is common and such infringement is difficult to prevent or prosecute.

The strength of patents in the field of pet therapeutics involves complex legal and scientific questions and can be uncertain. The patent applications that we own or license may fail to result in issued patents in the United States or in other foreign countries. Even if the patents do successfully issue, third parties may challenge the validity, enforceability or scope thereof, which may result in such patents being narrowed, invalidated or held unenforceable. Furthermore, even if they are unchallenged, our patents and patent applications may not adequately protect our intellectual property or prevent others from designing around our claims. If the breadth or strength of protection provided by the patent applications we own, in-license or pursue with respect to any of our current or future product candidates is threatened, it could threaten our ability to commercialize any of our current or future product candidates. Further, if we encounter delays in our development efforts, the period of time during which we could market any of our current or future product candidates under patent protection would be reduced. Since patent applications in the United States and most other countries are confidential for a period of time after filing, we cannot be certain that we were the first to file any patent application related to our product candidates. Furthermore, for patent applications in which claims are entitled to a priority date before March 16, 2013, an interference proceeding can be provoked by a third party or instituted by the U.S. PTO to determine who was the first to invent any of the subject matter covered by the patent claims of our applications. For patent applications containing a claim not entitled to a priority date before March 16, 2013, there is a greater level of uncertainty in the patent law with the

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passage of the America Invents Act, which brings into effect significant changes to the U.S. patent laws that have yet to be well defined, and which introduces new procedures for challenging pending patent applications and issued patents. A primary change under this reform is creating a “first to file” system in the United States, which requires us to minimize the time from invention to filing of a patent application.

Even where laws provide protection, costly and time-consuming litigation could be necessary to enforce and determine the scope of our proprietary rights, and the outcome of such litigation would be uncertain. Moreover, any actions we may bring to enforce our intellectual property against our competitors could provoke them to bring counterclaims against us, and some of our competitors have substantially greater intellectual property portfolios than we have.

We also rely on trade secret protection and confidentiality agreements to protect proprietary know-how that is not patentable, processes for which patents are difficult to enforce and any other elements of our product development processes that involve proprietary know-how, information or technology that is not covered by patents. Although we require all of our employees to assign their inventions to us, and endeavor to execute confidentiality agreements with all of our employees, consultants, advisors and any third parties who have access to our proprietary know-how, information or technology, we cannot be certain that we have executed such agreements with all parties who may have helped to develop our intellectual property or had access to our proprietary information, nor that our agreements will not be breached. We cannot guarantee that our trade secrets and other confidential proprietary information will not be disclosed or that competitors will not otherwise gain access to our trade secrets or independently develop substantially equivalent information and techniques. Further, the laws of some foreign countries do not protect proprietary rights to the same extent or in the same manner as the laws of the United States. As a result, we may encounter significant problems in protecting and defending our intellectual property both in the United States and abroad. If we are unable to prevent material disclosure of the intellectual property related to our technologies to third parties, we will not be able to establish or maintain a competitive advantage in our market, which could materially adversely affect our business, results of operations and financial condition.

Any disclosure to or misappropriation by third parties of our confidential proprietary information could enable competitors to quickly duplicate or surpass our technological achievements, thus eroding our competitive position in our market.

We may be involved in lawsuits to protect or enforce our patents or the patents of our licensors, which could be expensive, time-consuming and unsuccessful.

Competitors may infringe our patents, should any issue to us, or the patents of our licensors that are licensed to us. To counter infringement or unauthorized use, we may be required to file infringement claims, which can be expensive and time-consuming. In addition, if we or one of our future collaborators were to initiate legal proceedings against a third party to enforce a patent covering our current product candidates, or one of our future products, the defendant could counterclaim that our patent is invalid and/or unenforceable. In patent litigation in the United States, defendant counterclaims alleging invalidity and/or unenforceability are commonplace. Grounds for a validity challenge could be an alleged failure to meet any of several statutory requirements, including lack of novelty, obviousness or non-enablement. Grounds for an unenforceability assertion could be an allegation that someone connected with prosecution of the patent withheld relevant information from the U.S. PTO, or made a materially misleading statement, during prosecution. Third parties may also raise similar claims before the U.S. PTO, even outside the context of litigation. The outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to the validity question, for example, we cannot be certain that there is no invalidating prior art, of which we and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, we would lose at least part, and perhaps all, of the patent protection on our current or future product candidates. Such a loss of patent protection could have a material adverse impact on our business.

Litigation or interference proceedings may fail and, even if successful, may result in substantial costs and distract our management and other employees. Furthermore, because of the substantial amount of discovery required in

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connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments. If securities analysts or investors perceive these results to be unsuccessful, it could have an adverse effect on the price of our common stock. Finally, we may not be able to prevent, alone or with the support of our licensors, misappropriation of our trade secrets or confidential information, particularly in countries where the laws may not protect those rights as fully as in the United States.

Changes in U.S. patent law could diminish the value of patents in general, thereby impairing our ability to protect our products.

As is the case with other biopharmaceutical companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biopharmaceutical industry involves both technological and legal complexity. Therefore, obtaining and enforcing biopharmaceutical patents is costly, time-consuming and inherently uncertain. In addition, the United States has recently enacted and is currently implementing wide-ranging patent reform legislation. The Supreme Court has ruled on several patent cases in recent years, either narrowing the scope of patent protection available in certain circumstances or weakening the rights of patent owners in certain situations. In addition to increasing uncertainty with regard to our ability to obtain patents in the future, this combination of events has created uncertainty with respect to the value of patents, once obtained. Depending on decisions by the U.S. Congress, the federal courts, and the U.S. PTO, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing licensed patents and patents that we might obtain in the future.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

The U.S. PTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other provisions during the patent process. There are situations in which noncompliance can result in abandonment or lapse of a patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. In such an event, competitors might be able to enter the market earlier than would otherwise have been the case, which would have an adverse effect on our business.

We have filed a trademark application for our company name and have not yet registered trademarks for commercial trade names for our current product candidates in the United States or any other countries, and failure to secure those registrations could adversely affect our business.

We have filed a trademark application for our company name, although we cannot make assurances that the trademark will become registered. We have not yet registered any trademarks for commercial trade names for any of our current product candidates in the United States or any other countries. During trademark registration proceedings, we may receive rejections. Although we are given an opportunity to respond to those rejections, we may be unable to overcome such rejections. In addition, in the U.S. PTO and in comparable agencies in many foreign jurisdictions, third parties are given an opportunity to oppose pending trademark applications and to seek to cancel registered trademarks. Opposition or cancellation proceedings may be filed against our trademarks, and our trademarks may not survive such proceedings. Moreover, any name we propose to use with our product candidates in the United States must be approved by the CVM, regardless of whether we have registered it, or applied to register it, as a trademark. The CVM typically conducts a review of proposed product names, including an evaluation of potential for confusion with other product names. If the CVM objects to any of our proposed proprietary product names, we may be required to expend significant additional resources in an effort to identify a suitable substitute name that would qualify under applicable trademark laws, not infringe the existing rights of third parties and be acceptable to the CVM.

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We may not be able to protect our intellectual property rights throughout the world.

Filing, prosecuting and defending patents on product candidates throughout the world would be prohibitively expensive. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their own products and, further, may export otherwise infringing products to territories where we have patent protection, but where enforcement is not as strong as that in the United States. These products may compete with our products in jurisdictions where we do not have any issued or licensed patents and our patent claims or other intellectual property rights may not be effective or sufficient to prevent them from so competing.

Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents and other intellectual property protection, particularly those relating to biopharmaceuticals, which could make it difficult for us to stop the infringement of our patents or marketing of competing products in violation of our proprietary rights generally. Proceedings to enforce our patent rights in foreign jurisdictions could result in substantial cost and divert our efforts and attention from other aspects of our business.

We may be subject to claims that our employees, consultants or independent contractors have wrongfully used or disclosed confidential information of third parties.

We have received confidential and proprietary information from third parties. In addition, we employ individuals who were previously employed at other biotechnology, pharmaceutical or animal health companies. We may be subject to claims that we or our employees, consultants or independent contractors have inadvertently or otherwise improperly used or disclosed confidential information of these third parties or our employees’ former employers. Litigation may be necessary to defend against these claims. Even if we are successful in defending against these claims, litigation could result in substantial cost and be a distraction to our management and employees.

Risks Related to Government Regulation

The regulatory approval process is uncertain, requires us to utilize significant resources, and may prevent us or our collaboration partners from obtaining approvals for the commercialization of some or all of our drug candidates.

The research, testing, manufacturing, labeling, approval, selling, import, export, marketing and distribution of pet therapeutics are subject to extensive regulation by the CVM and other regulatory authorities in the United States and other countries, which regulations differ from country to country. Neither we nor any collaboration partner is permitted to market any of our current or future product candidates in the United States until we receive approval of an NADA from the CVM. We have not submitted an application for or received marketing approval for our current product candidates. Obtaining approval of an NADA can be an uncertain process that requires us to utilize significant resources. In addition, failure to comply with CVM and other applicable United States and foreign regulatory requirements may subject us to administrative or judicially imposed sanctions, including: warning letters, civil and criminal penalties, injunctions, withdrawal of approved products from the market, product seizure or detention, product recalls, total or partial suspension of production, and refusal to approve pending NADAs or supplements to approved NADAs.

To gain approval to market a pet therapeutic for a particular species of pet, we must provide the CVM and foreign regulatory authorities with data from animal safety and effectiveness studies that adequately demonstrate the safety and efficacy of that product in the target animal for the intended indication applied for in the NADA or other regulatory filing. The development of pet therapeutics in a target animal is a lengthy, expensive and uncertain process, and delay or failure can occur at any stage of any of our development efforts. Success in prior target animal studies or in the treatment of human beings with a product candidate does not ensure that our target animal studies will be successful and the results of development efforts by other parties may not be indicative of the results of our target animal studies and other development efforts.

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Regulatory approval of an NADA or supplement NADA is not guaranteed, and the approval process requires us to utilize significant resources, may take several years, and is subject to the substantial discretion of the CVM. Despite the time and expense exerted, failure can occur at any stage, and we could encounter problems that cause us to abandon or repeat studies, or perform additional studies. If any of our current or future product candidates fails to demonstrate safety and efficacy in our studies, or for any other reason does not gain regulatory approval, our business and results of operations will be materially and adversely harmed.

Even if we receive regulatory approval for any of our current or future product candidates, we will be subject to ongoing CVM obligations and continued regulatory review, which may result in significant additional expense. Additionally, any product candidates, if approved, will be subject to labeling and manufacturing requirements and could be subject to other restrictions. Failure to comply with these regulatory requirements or the occurrence of unanticipated problems with our products could result in significant penalties.

Any regulatory approvals that we or any of our collaborators receive for any of our current or future product candidates may be subject to conditions of approval or limitations on the approved indicated uses for which the product may be marketed, or may contain requirements for potentially costly surveillance to monitor the safety and efficacy of the product candidate. In addition, if the CVM approves any of our current or future product candidates, the manufacturing processes, labeling, packaging, distribution, adverse event reporting, storage, advertising, promotion and recordkeeping for the product will be subject to extensive and ongoing regulatory requirements. These requirements include submissions of safety and other post-marketing information and reports, registration, as well as continued compliance with cGMP, GLP and good clinical practices, or GCP, for any studies that we conduct post-approval. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with our third-party manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may result in, among other things:

The CVM’s policies may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our product candidates. We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the United States or abroad. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained and we may not achieve or sustain profitability, which would adversely affect our business.

Failure to obtain regulatory approvals in foreign jurisdictions for our product candidates would prevent us from marketing our products internationally.

In order to market any product outside of the United States, including in the EEA (which is comprised of the 27 member states of the European Union plus Norway, Iceland and Liechtenstein) and many other foreign jurisdictions, separate regulatory approvals are required. More concretely, in the EEA, pet therapeutics can only be commercialized after obtaining a Marketing Authorization, or MA. Before granting the MA, the EMA or the competent authorities of the member states of the EEA make an assessment of the risk-benefit balance of the product on the basis of scientific criteria concerning its quality, safety and efficacy.

The approval procedures vary among countries and can involve additional studies and testing, and the time required to obtain approval may differ from that required to obtain CVM approval. Animal studies conducted in one

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country may not be accepted by regulatory authorities in other countries. Approval by the CVM does not ensure approval by regulatory authorities in other countries, and approval by one or more foreign regulatory authorities does not ensure approval by regulatory authorities in other foreign countries or by the CVM. However, a failure or delay in obtaining regulatory approval in one country may have a negative effect on the regulatory process in others. The foreign regulatory approval process may include all of the risks associated with obtaining CVM approval. We may not be able to file for regulatory approvals or to do so on a timely basis and, even if we do file it, we may not receive necessary approvals to commercialize our products in any market.

If approved, any of our current or future products may cause or contribute to adverse medical events that we are required to report to the CVM and regulatory authorities in other countries and, if we fail to do so, we could be subject to sanctions that would materially harm our business.

If we are successful in commercializing any of our current or future products, regulations of the CVM and of the regulatory authorities in other countries require that we report certain information about adverse medical events if those products may have caused or contributed to those adverse events. The timing of our obligation to report would be triggered by the date we become aware of the adverse event as well as the nature of the event. We may fail to report adverse events we become aware of within the prescribed timeframe. We may also fail to appreciate that we have become aware of a reportable adverse event, especially if it is not reported to us as an adverse event or if it is an adverse event that is unexpected or removed in time from the use of our products. If we fail to comply with our reporting obligations, the CVM and regulatory authorities in other countries could take action including criminal prosecution, the imposition of civil monetary penalties, seizure of our products, or delay in approval or clearance of future products.

Legislative or regulatory reforms with respect to pet therapeutics may make it more difficult and costly for us to obtain regulatory clearance or approval of any of our current or future product candidates and to produce, market, and distribute our products after clearance or approval is obtained.

From time to time, legislation is drafted and introduced in the U.S. Congress that could significantly change the statutory provisions governing the testing, regulatory clearance or approval, manufacture, and marketing of regulated products. In addition, CVM regulations and guidance are often revised or reinterpreted by the CVM in ways that may significantly affect our business and our products. Similar changes in laws or regulations can occur in other countries. Any new regulations or revisions or reinterpretations of existing regulations in the United States or in other countries. may impose additional costs or lengthen review times of any of our current or future product candidates. We cannot determine what effect changes in regulations, statutes, legal interpretation or policies, when and if promulgated, enacted or adopted may have on our business in the future. Such changes could, among other things, require:

Each of these would likely entail substantial time and cost and could materially harm our financial results. In addition, delays in receipt of or failure to receive regulatory clearances or approvals for any future products would harm our business, financial condition, and results of operations.

Our research and development relies on evaluations in animals, which may become subject to bans or additional regulations.

As a biopharmaceutical company with a focus on pet therapeutics, the evaluation of our existing and new products in animals is required to register our products. Animal testing in certain industries has been the subject of controversy and adverse publicity. Some organizations and individuals have attempted to ban animal testing or encourage the adoption of additional regulations applicable to animal testing. To the extent that the activities of such

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organizations and individuals are successful, our research and development, and by extension our operating results and financial condition, could be materially adversely affected. In addition, negative publicity about us or our industry could harm our reputation.

Risks Related to Our Common Stock and this Offering

Our stock price may be volatile and you may not be able to resell shares of our common stock at or above the price you paid.

The trading price of our common stock following this offering could be highly volatile and could be subject to wide fluctuations in response to various factors, some of which are beyond our control. These factors include those discussed in this “Risk Factors” section of this prospectus and others, such as:

In addition, the stock market in general, or the market for stocks in our industry or industries related to our industry, may experience extreme volatility unrelated to the operating performance of the issuer. These broad market fluctuations may adversely affect the trading price or liquidity of our common stock. In the past, when the market price of a stock has been volatile, holders of that stock have sometimes instituted securities class action litigation against the issuer. If any of our stockholders were to bring such a lawsuit against us, we could incur substantial costs defending the lawsuit and the attention of our management would be diverted from the operation of our business.

An active, liquid and orderly market for our common stock may not develop, and you may not be able to resell your common stock at or above the public offering price.

Prior to this offering, there has been no public market for shares of our common stock, and an active public market for our shares may not develop or be sustained after this offering. We and the representatives of the underwriters will determine the initial public offering price of our common stock through negotiation. This price will not necessarily reflect the price at which investors in the market will be willing to buy and sell our shares following this offering. In addition, an active trading market may not develop following completion of this offering or, if it is developed, may not be sustained. The lack of an active market may impair your ability to sell your shares

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at the time you wish to sell them or at a price that you consider reasonable. An inactive market may also impair our ability to raise capital by selling shares and may impair our ability to in-license or acquire other product candidates, businesses or technologies using our shares as consideration.

If securities or industry analysts do not publish research or reports about our business, or if they issue an adverse or misleading opinion regarding our stock, our stock price and trading volume could decline.

The trading market for our common stock will be influenced by the research and reports that industry or securities analysts publish about us or our business. We do not currently have and may never obtain research coverage by securities and industry analysts. If no or few securities or industry analysts commence coverage of us, the trading price for our stock would be negatively impacted. In the event we obtain securities or industry analyst coverage, if any of the analysts who cover us issue an adverse or misleading opinion regarding us, our business model, our intellectual property or our stock performance, or if our target animal studies and operating results fail to meet the expectations of analysts, our stock price would likely decline. If one or more of these analysts cease coverage of us or fail to publish reports on us regularly, we could lose visibility in the financial markets, which in turn could cause our stock price or trading volume to decline.

We are an “emerging growth company,” as defined in the JOBS Act, and as a result of the reduced disclosure and governance requirements applicable to emerging growth companies, our common stock may be less attractive to investors.

We are an “emerging growth company,” as defined in the JOBS Act, and we intend to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved. We cannot predict if investors will find our common stock less attractive because we will rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile. We may take advantage of these reporting exemptions until we are no longer an emerging growth company. We will remain an emerging growth company until the earlier of (1) the last day of the fiscal year (a) following the fifth anniversary of the completion of this offering, (b) in which we have total annual gross revenue of at least $1.0 billion, or (c) in which we are deemed to be a large accelerated filer, which means the market value of our common stock that is held by non-affiliates exceeds $700 million as of the prior June 30, and (2) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period.

Purchasers in this offering will experience immediate and substantial dilution in the book value of their investment.

The initial public offering price of our common stock is substantially higher than the pro forma net tangible book value per share of our common stock before giving effect to this offering. Accordingly, if you purchase our common stock in this offering, you will incur immediate substantial dilution of approximately $8.56 per share, representing the difference between the assumed initial public offering price of $12.00 per share, the midpoint of the price range set forth on the cover page of this prospectus, and our pro forma as adjusted net tangible book value as of March 31, 2013. In addition, following this offering, and assuming the sale by us of 4,250,000 shares of our common stock in this offering at the assumed initial public offering price of $12.00 per share, purchasers in this offering will have contributed approximately 54.1% of the total gross consideration paid by stockholders to us to purchase shares of our common stock through March 31, 2013, but will own only approximately 23.5% of the shares of common stock outstanding immediately after this offering. Furthermore, if the underwriters exercise their option to purchase additional shares of our common stock or outstanding options are exercised, you could experience further dilution. For a further description of the dilution that you will experience immediately after this offering, see the section in this prospectus entitled “Dilution.”

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If we sell shares of our common stock in future financings, stockholders may experience immediate dilution and, as a result, our stock price may decline.

We may from time to time issue additional shares of common stock at a discount from the current trading price of our common stock. As a result, our stockholders would experience immediate dilution upon the sale of any shares of our common stock at such discount. In addition, as opportunities present themselves, we may enter into financing or similar arrangements in the future, including the issuance of debt securities, preferred stock or common stock. If we issue common stock or securities convertible into common stock, our common stockholders would experience additional dilution and, as a result, our stock price may decline.

Our principal stockholders and management own a significant percentage of our stock and will be able to exert significant control over matters subject to stockholder approval.

Upon the closing of this offering and based on shares outstanding as of March 31, 2013, our executive officers, directors, holders of 5% or more of our capital stock and their respective affiliates will beneficially own approximately 62% of our voting stock (assuming no exercise of the underwriters’ option to purchase additional shares of our common stock and no exercise of outstanding options). These stockholders will have the ability to influence us through this ownership position and may be able to determine all matters requiring stockholder approval. For example, these stockholders may be able to control elections of directors, amendments of our organizational documents, or approvals of any merger, sale of assets or other major corporate transaction. This may prevent or discourage unsolicited acquisition proposals or offers for our common stock that you may feel are in your best interest as one of our stockholders.

Sales of a substantial number of shares of our common stock in the public market could cause our stock price to fall.

If our existing stockholders sell, or indicate an intention to sell, substantial amounts of our common stock in the public market after the lock-up and other legal restrictions on resale discussed in this prospectus lapse, the trading price of our common stock could decline. Based upon the number of shares outstanding as of March 31, 2013, upon the closing of this offering, we will have outstanding a total of 19,071,505 shares of common stock, which includes 1,021,578 shares of restricted stock that are not considered outstanding for accounting purposes, assuming (i) the conversion of all outstanding shares of our convertible preferred stock into 12,596,115 shares of our common stock, which we expect to automatically occur immediately prior to the closing of the offering, (ii) the issuance of 309,838 shares of common stock to the holders of our series A, B and C convertible preferred stock upon the closing of this offering in satisfaction of accumulated and unpaid dividends, as required by the terms of our series A, B and C convertible preferred stock, assuming for this purpose that the closing of this offering occurred on March 31, 2013 at an assumed initial public offering price of $12.00 per share, the midpoint of the price range listed on the cover page of this prospectus, (iii) no exercise of the underwriters’ option to purchase additional shares of our common stock, and (iv) no exercise of options outstanding as of March 31, 2013. Of these shares, approximately 4,250,000 shares of our common stock, plus any shares sold upon exercise of the underwriters’ option to purchase additional shares of our common stock, will be freely tradable, without restriction, in the public market immediately following this offering. Stifel, Nicolaus & Company, Incorporated and Lazard Capital Markets LLC, however, may, in their sole discretion, permit our officers, directors and other stockholders who are subject to these lock-up agreements to sell shares prior to the expiration of the lock-up agreements.

The lock-up agreements pertaining to this offering will expire 180 days from the date of this prospectus. After the lock-up agreements expire, up to an additional 14,821,505 shares of common stock, subject to vesting schedules, will be eligible for sale in the public market, 9,885,769 of which shares are held by directors, executive officers and other affiliates and will be subject to vesting schedules or volume limitations under Rule 144 under the Securities Act.

In addition, shares of common stock that are either subject to outstanding options or reserved for future issuance under our equity incentive plans will become eligible for sale in the public market to the extent permitted by the provisions of various vesting schedules, the lock-up agreements and Rule 144 and Rule 701 under the Securities Act. If these additional shares of common stock are sold, or if it is perceived that they will be sold, in the public market, the trading price of our common stock could decline.

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After this offering, the holders of 13,216,670 shares of our common stock, or approximately 89% of our total outstanding common stock as of March 31, 2013, will be entitled to rights with respect to the registration of their shares under the Securities Act, subject to vesting schedules and to the lock-up agreements described above. Registration of these shares under the Securities Act would result in the shares becoming freely tradable without restriction under the Securities Act, except for shares purchased by affiliates. Any sales of securities by these stockholders could have a material adverse effect on the trading price of our common stock.

We have broad discretion to determine how to use the funds raised in this offering, and may use them in ways that may not enhance our operating results or the price of our common stock.

Our management will have broad discretion over the use of proceeds from this offering, and we could spend the proceeds from this offering in ways our stockholders may not agree with or that do not yield a favorable return, if at all. We intend to use the net proceeds of this offering for in-licensing and developing additional product candidates, commercialization of our current and future product candidates, including establishing a direct sales organization in the United States, and for general corporate and working capital purposes. However, our use of these proceeds may differ substantially from our current plans. If we do not invest or apply the proceeds of this offering in ways that improve our operating results, we may fail to achieve expected financial results, which could cause our stock price to decline.

Provisions in our charter documents and under Delaware law could discourage a takeover that stockholders may consider favorable and may lead to entrenchment of management.

Our restated certificate of incorporation and amended and restated bylaws that will be in effect immediately prior to the consummation of this offering will contain provisions that could delay or prevent changes in control or changes in our management without the consent of our board of directors. These provisions will include the following:

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In addition, these provisions would apply even if we were to receive an offer that some stockholders may consider beneficial.

We are also subject to the anti-takeover provisions contained in Section 203 of the Delaware General Corporation Law. Under Section 203, a corporation may not, in general, engage in a business combination with any holder of 15% or more of its capital stock unless the holder has held the stock for three years or, among other exceptions, the board of directors has approved the transaction. For a description of our capital stock, see the section in this prospectus entitled “Description of Capital Stock.”

We do not currently intend to pay dividends on our common stock, and, consequently, your ability to achieve a return on your investment will depend on appreciation in the price of our common stock.

We do not currently intend to pay any cash dividends on our common stock for the foreseeable future. We currently intend to invest our future earnings, if any, to fund our growth. Additionally, the terms of our credit facility restrict our ability to pay dividends. Therefore, you are not likely to receive any dividends on your common stock for the foreseeable future. Since we do not intend to pay dividends, your ability to receive a return on your investment will depend on any future appreciation in the market value of our common stock. There is no guarantee that our common stock will appreciate or even maintain the price at which our holders have purchased it.

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