Illustrations: Leanne Rule

Inside a Facebook ‘Dallas Buyers Club’ for Cat Drugs

Desperate pet owners must either buy illegal medications or watch their cats die

Carrie Arnold
Published in
12 min readJul 15, 2020


A single glance at the foster kitten told veterinarian Jessica Thompson all she needed to know. Harper’s once-velvety gray coat was greasy and dull. She was still small — just five pounds — but her abdomen swelled like she had a baseball in her stomach. In the clinic, Thompson used a syringe to remove cloudy, yellowish fluid from the five-month-old cat. She had seen these symptoms two years before, in two other foster kittens. The disease, known as feline infectious peritonitis, is caused by a mutant form of a common feline virus. It most frequently strikes cats at the beginning and end of their lives, when their immune system is the weakest. Historically, FIP has been 100% fatal.

The family that had begun the process of adopting Harper had already fallen in love with the gray fluffball, and Harper’s new mom broke down at the news.

“At that point, I didn’t care,” said Thompson. “I just wanted to save Harper because I wasn’t going to have another FIP kitten die if I could save its life.”

Thompson knew there was another option, but it was a risky one. Several months before, another family told her of a new drug called GS-441524 that could cure cats of FIP. They had learned about it via a 22,000-member Facebook group called FIP Warriors. Digging into the research, Thompson found an early 2019 pilot study led by veterinarian Niels Pedersen at the University of California, Davis showing that an 84-day course of GS-441524 cured 25 out of 31 cats. The good news had only one catch: The drug was only available on the black market.

“It’s like the Dallas Buyers Club, when patients couldn’t get the AIDS meds they needed in this country legally.”

Gilead Sciences, the pharmaceutical company that developed the drug, hadn’t taken the final step to get it approved for veterinary use by the U.S. Food and Drug Administration because it was afraid any adverse events in cats would torpedo the company’s ability to get GS-441524 approved for human use, according to Pedersen. The drug was originally developed for people and is…



Carrie Arnold
Writer for

Just your friendly neighborhood public health reporter, covering the intersection of health and environment. Lover of coffee, knitting, cycling, and cats.