Seizures among side effects from popular flea and tick medications for pets

RUTHERFORD, N.J. – A visit to the vet changed the lives of a New Jersey woman and her dog.

In November, a veterinarian recommended that Tugba Aksoy have her dog Lokum switch from his flea and tick collar to Simparica, a newer class of prescription-only flea and tick medications. Lokum seemed happy enough with his collar, but the idea of a once-a-month pill sounded like a good idea. Aksoy decided to make the switch.

That night, she heard Lokum howling. It turned out he was having a seizure. She rushed him to the emergency room at an animal hospital, where a veterinarian told her Lokum’s seizure was likely caused by the new medication.

He continued to have seizures for months, sometimes as many as 11 in a row.

In April, Aksoy posted video of Lokum having seizures. Nearly 22,000,000 people have seen it. She said she posted it to YouTube and Facebook so other people would know.

“I wanted to warn everyone, because anyone can be in my situation,” she said. “I trusted the vet. I didn’t do my own research. I think we’re naive enough to think once we get it from the vet, it’s perfectly safe unless they say something.”

Simparica, Nexgard, Bravecto and Credelio are all drugs in the isoxazoline class. They attack the neurological systems of biting fleas and tickets, killing them. While sales have skyrocketed over the last five years they’ve been on the market, information about some troubling side effects is coming to light.

Through the Freedom of Information Act, WPIX obtained hundreds of pages of reports sent to the Food and Drug Administration by veterinarians and pet owners concerned about side effects from the drugs.

Seizures were at the top of the list, with documents showing 1,315 seizures from Nexgard in the five years since the FDA approved it as safe and effective for most dogs. That same information showed 720 reported seizures for Bravecto in four years and 557 for Simparica in three years. For Credelio, six seizures were reported in the first six months after its approval.

The manufacturers said the risk of side effects is rare, less than one in 10,000 doses sold. Seizures are mentioned as a potential side effect, but the information isn't always easy to find. Last September, the FDA sent an alert advising pet owners and veterinarians to be “aware of the potential for neurologic adverse events in dogs and cats when treated with drugs that are in the isoxazoline class.”

The agency called for new labeling:

“The FDA is working with manufacturers of isoxazoline products to include new label information to highlight neurologic events because these events were seen consistently across the isoxazoline class of products. Revolution Plus, which was approved most recently, includes the new labeling information to highlight the potential for neurologic events in the isoxazoline class, and Merial has made the requested changes to Nexgard's labeling including adding the new class statement.”

Aksoy told WPIX she wished she’d known about the side effects beforehand.

“If you know the side effects, why wouldn’t you just say that and leave that up to me to see if I want to take that chance? I would not take that chance even if it was one in a million,” she said.

Lokum now takes anti-seizure medication twice a day and has seen several specialists.

His medical care has cost $10,000 so far. The drug’s manufacturer, Zoetis, sent Aksoy $3,300 but said they couldn’t do that on an ongoing basis. After WPIX intervened, a company executive reached out and asked her to submit her medical expenses for possible reimbursement.

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