Zoetis Receives EU Approval for Portela® (relfovetmab), the First Three-Month Monoclonal Antibody Therapy for Osteoarthritis Pain in Cats
Zoetis Inc. (NYSE: ZTS), the world leader in animal health, today annonced that the European Commission has granted marketing authorization for Portela® (relfovetmab), marking a major milestone in feline pain management. Portela is the first monoclonal antibody (mAb) therapy approved in the European Union with a three-month dosing interval for the alleviation of pain associated with osteoarthritis (OA) in cats.
Designed to deliver up to three months of OA pain relief from a single injection, Portela targets nerve growth factor (NGF)—a critical mediator of osteoarthritis pain and inflammation. This innovative mechanism provides veterinarians and cat owners with a long-acting, convenient treatment option for managing chronic pain in cats, a condition that is often underdiagnosed and undertreated.
The Committee for Veterinary Medicinal Products (CVMP) of the European Medicines Agency had recommended marketing authorization for Portela in September 2025, following a positive assessment of its safety and efficacy. The recommendation was based on a comprehensive review of preclinical data and clinical field studies, including a nine-month European field trial in which Portela demonstrated both significant pain alleviation and strong tolerability—even among cats with pre-existing kidney disease at IRIS stages 1, 2, and 3.
A Breakthrough in Feline Pain Management
“The European Commission’s marketing authorization for Portela marks a pivotal advancement in feline pain management,” said Rob Polzer, Ph.D., Executive Vice President and President, Research and Development at Zoetis. “Portela’s long-acting antibody properties and unique binding to NGF offer veterinarians and cat owners across the European Union an innovative, approved option to manage osteoarthritis-related pain. This milestone reflects our continued commitment to advancing therapies that improve the health and well-being of companion animals.”
Osteoarthritis is a chronic, progressive joint disease characterized by joint inflammation, cartilage degradation, and persistent pain. While the disease itself cannot be cured, effective pain management can significantly enhance mobility and quality of life for affected cats. Studies show that up to 40% of cats exhibit clinical signs of OA, yet only 18% of those cases are diagnosed by veterinarians, largely because cats instinctively hide their pain and owners often interpret behavioral changes as normal aging.
Chronic pain affects more than just mobility—it can impair sleep, cognition, and social behavior, ultimately reducing a cat’s overall well-being. Portela addresses this challenge by offering sustained pain relief in a single injection administered every three months, which is particularly beneficial for cats that are difficult to medicate on a daily or monthly basis.
“Osteoarthritis in cats is often underestimated because they’re so good at hiding pain,” explained Dr. Marieke Knies, Dipl. ECVIM, internal medicine specialist in the Netherlands. “Behavioral changes are frequently dismissed as signs of aging, when they may actually indicate chronic discomfort. New therapies like Portela that provide lasting pain relief without daily administration represent a real step forward—for cats, their owners, and veterinarians alike.”
Expanding Zoetis’ Leadership in OA Pain Solutions
The approval of Portela expands Zoetis’ leadership in osteoarthritis pain management and strengthens its growing portfolio of monoclonal antibody therapies. Portela joins Solensia® (frunevetmab)—the first anti-NGF monoclonal antibody approved for monthly alleviation of OA pain in cats—which is now available in more than 40 countries worldwide. Both therapies exemplify Zoetis’ commitment to delivering science-driven innovations that address significant unmet medical needs in animal health.
Clinical trials and four years of real-world experience have shown that Solensia provides consistent, reliable pain relief that enhances cats’ mobility and quality of life. As with any medicine, there are potential side effects. For Solensia, the most common (affecting up to 1 in 10 cats) include hair loss, dermatitis, and itching. Rarely, cats may experience injection site reactions or skin lesions, and very rarely, anaphylaxis.
For Portela, data from clinical studies indicate that the most common side effect (affecting more than 1 in 10 cats) is transient pain upon injection, followed by dermatitis (up to 1 in 10 cats). Uncommon effects (up to 10 in 1,000 cats) include pruritus, skin scabs, localized swelling, and hair loss at the injection site. Overall, Portela was found to be well tolerated, with a favorable safety profile consistent with its mechanism of action.
A Step Forward in Feline Health and Comfort
“Portela is a new, science-driven therapy designed to support long-term comfort and mobility for cats—with the added benefit that pet owners only need to bring their cats in for an injection once every three months,” said Richard Goldstein, DVM, DACVIM, DECVIM-CA, Global Chief Medical Officer and Head of Medical Affairs at Zoetis. “This is a testament to our focus on meaningful innovation in feline medicine and our dedication to addressing the unmet needs of our patients and their families. We’re proud to provide veterinarians with another effective tool to help improve the quality of life for the cats in their care.”
Zoetis anticipates commercial availability of Portela in the European Union in 2026, following the completion of manufacturing and distribution preparations. With its extended duration of action, Portela represents an important new option for managing chronic OA pain, simplifying treatment schedules, and improving adherence—both for veterinarians and for cat owners seeking better, longer-lasting relief for their pets.
The approval underscores Zoetis’ ongoing investment in innovative monoclonal antibody therapies that redefine how chronic pain is managed in companion animals. Building on the success of Solensia and Librela® (for dogs), Portela reinforces Zoetis’ position as a global leader in pain management solutions for pets.
About Zoetis
As the world’s leading animal health company, Zoetis is driven by a singular purpose: to nurture our world and humankind by advancing care for animals. After innovating ways to predict, prevent, detect, and treat animal illness for more than 70 years, Zoetis continues to stand by those raising and caring for animals worldwide – from veterinarians and pet owners to livestock producers. The company’s leading portfolio and pipeline of medicines, vaccines, diagnostics and technologies make a difference in over 100 countries. A Fortune 500 company, Zoetis generated revenue of $9.3 billion in 2024 with approximately 13,800 employees.
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