Canine arthritis treatment is under fire after reports of serious, even fatal side effects

A popular medication for arthritis in dogs may be riskier than we thought. This week, the Food and Drug Administration reported several serious adverse events and deaths associated with the recently approved drug Librela.

On Monday, the FDA Center for Veterinary Medicine issued a letter to the veterinarians detailing the results of their research on Librela. The FDA identified numerous serious adverse effects related to its use, including seizures and loss of muscle function; Several dogs also reportedly died or were euthanized due to these complications. The agency recommends that the drug’s manufacturer update its labeling to include these potential side effects and advises veterinarians and the public to report any adverse events related to its use.

The active ingredient in Librela, bedinvetmab, It is a laboratory-made antibody developed by the company Zoetis. In 2023, the FDA approved It is to treat osteoarthritis in dogs. The drug, which is administered by injection once a month, targets and inhibits a protein involved in pain regulation called canine nerve growth factor (NGF). The medication is designed to reduce NGF levels, which tend to be higher in dogs with osteoarthritis. It is the first monoclonal antibody-based drug approved in dogs and the second approved for pets.

At the time of its approval, some of the most common side effects associated with Librela were certain types of infections (UTIs, bacterial skin infections), rash, vomiting, and weight loss. As is customary with all approved medications, the FDA has been monitoring reports of adverse events associated with Librela brought to it by patients and physicians. And some dog owners have reported very serious, even life-threatening, symptoms in their pets after they started taking Librela.

According to the FDA, there have been 3,674 reports of adverse events related to Librela, as of March 2024. These adverse events have been more common among older dogs, which makes sense given that age is a common risk factor for osteoarthritis. The FDA identified many potentially serious adverse events that are not currently included in the drug label as possible side effects. These include ataxia (poor muscle control), seizures, diarrhea and paralysis. In some cases, dogs died or were euthanized shortly after developing these serious events.

In one case report, for example, a 10-year-old boy from the Great Pyrenees developed ataxia one hour after taking Librela. Within a day, the dog developed incontinence and lameness in his hind legs, which eventually spread to his front legs. After two days, the dog was paralyzed. Four days after taking the drug, the dog died.

The FDA is careful to note that these adverse events have not been conclusively linked to Librela as of yet. At the same time, the agency dismissed the idea, raised by Zoetis, that the large number of drug-related reports was simply due to negative publicity on social media.

“There is no evidence that the reported cases are not true cases associated with Librela,” the agency wrote in its report. review of these reports.

Zoetis issued a statement following the FDA letter. The company criticized some media coverage for allegedly mischaracterizing the FDA communication as a “warning” rather than an “informational update” intended to educate veterinarians and the public. The company also argued, based on data from the European Union, that any identified adverse events associated with Librela are likely rare.

“We remain confident in the safety and effectiveness of Librela and are committed to supporting veterinarians and pet owners to help dogs live with less pain and greater mobility,” the company said in its statement.

More time and research will be needed to confirm these serious side effects. But in the meantime, the FDA has recommended that Zoetis update Librela’s labeling to mention these potential adverse events (the Center for Veterinary Medicine itself cannot require safety-related labeling changes).

While Zoetis defends its drug, it said it was discussing possible labeling changes with the FDA. The FDA also recommends dog owners and veterinarians continue to report adverse events associated with use of the drug.