News|Articles|October 29, 2025

Long-acting therapy for relieving OA pain in cats receives European marketing authorization

Zoetis' relfovetmab product is a long-acting anti-nerve growth factor monoclonal therapy for cats.

A monoclonal antibody (mAb) therapy with a 3-month dosing interval for relieving pain associated with feline osteoarthritis (OA) will be available in Europe in 2026. Marketing authorization for relfovetmab (Portela; Zoetis) has been granted by the European Commission, according to Zoetis¹, making it the first long-acting anti-nerve growth factor (NGF) mAB therapy for cats to be made accessible by prescription in Europe.²

The marketing authorization—similar to an FDA approval in the US³—follows a recommendation issued by the European Medicines Agency's Committee for Veterinary Medicinal Products (CVMP) on September 10, 2025.^2,4The committee’s recommendation for marketing authorization was based on a positive benefit-risk balance of the safety and efficacy data submitted by Zoetis.²

“The benefits of Portela are significantly improved scores as assessed by cat owners using client-specific outcome measures, and reduced pain as assessed by veterinarians using a categorical pain assessment. These improvements were consistent over a 270-day period.” The CVMP wrote in its opinion summary.⁴

Rob Polzer, PhD, executive vice president and president of research and development at Zoetis, said the marketing authorization represents a “pivotal advancement” for pain management in cats. “Portela’s long-acting antibody properties and its unique binding site to NGF now provide veterinarians and cat owners across the European Union with another innovative, approved option to manage osteoarthritis-related pain. This milestone reflects our continued commitment to advancing innovative therapies that enhance the health and well-being of companion animals,” Polzer said in a news release.¹

OA is very common in cats, affecting mobility and quality of life.^1,5Although less than 20% of felines are diagnosed with OA, up to 40% of cats have clinical signs of the chronic and progressive joint disease, while many other cases go undiagnosed.¹

“The statistics show that about 60% of cats over the age of 6 [years] have x-ray evidence of arthritis, and 90% of cats over the age of 12 [years] have radiographic [OA]," Kristin Kirkby Shaw, DVM, PhD, MS, DACVS-SA, CACVSMR, founder of Canine Arthritis Resources and Education (CARE), said in a dvm360 interview.⁵

“Osteoarthritis in cats is often underestimated because they’re so good at hiding pain. Behavioral changes are frequently seen as ‘just getting older’ when they may in fact be signs of long-term discomfort. New therapies that provide lasting pain relief without daily administration are a real step forward - for cats, their owners, and veterinarians,” Marieke Knies, DVM, DECVIM, internal medicine specialist in the Netherlands, said in the release.¹

Relfovetmab targets anti-NGF, a mediator of OA pain and inflammation, with a single injection. A 9-month field study in Europe demonstrated the effectiveness of the drug in relieving pain associated with OA. The study also showed that relfovetmab was well-tolerated by patients, including felines with kidney disease at IRIS stages 1, 2, or 3.¹

The most reported adverse effects of relfovetmab are immediate pain upon injection and dermatitis. Less common adverse effects include pruritus, skin scabs, injection site swelling, and injection site hair loss, according to CVMP.⁴

Relfovetmab is designed to support long-term comfort and mobility for cats, and with the benefit for pet owners that now only need to bring their cats in for an injection once every 3 months, according to Richard Goldstein, DVM, DACVIM, DECVIM-CA, global chief medical officer and head of medical affairs at Zoetis. “We look forward to providing veterinarians with another innovative tool, adding to our wide feline portfolio, to help them improve the quality of life for the cats in their care,” Goldstein said in the release.¹

References