Rimadyl Side Effects in Cats

Dear Dr. Neely,

Four of my cats have been sterilized. I don't know why but the vet gave three injections of Rimadyl to each of them every other day after the surgery.

In a week and a half, two of my kitties suddenly died (with a couple of days difference).There was paralysis of the breathing center and of the rear legs.

Another vet taking care of the remaining kitties needs to know how long it takes to eliminate rimadyl in cats?

I know from your site that the danger is that it starts to kill the animal later, it lasts longer. But can you provide any more accurate info? I mean - in what time can I be more or less sure that the kitties are out of danger already?

And what cure would you recommend to administer now to save them?

Thank you very much!



Dear Taras,

I am SO sorry to hear what happened to your kittens. The half-life of Rimadyl in cats is 20 hours. The half life refers to the time it takes for one half of the medication to be broken down and eliminated from the body.

That means that 20 hours after the last dose of medication, 1/2 of the Rimadyl is still active. But it's not enough to just consider half life. Even if all of the medication is out of the body approximately 2 days after the last dosage, the damage that has already been done to your cat can persist and cause continued deterioration. Also, since multiple doses were given, that time can be extended and the damage more severe.

A few of the possible complications of Rimadyl are GI bleeding, liver damage/failure, kidney problems/failure and nausea and vomiting.

My best advise would be to maintain the cats with supportive care (IV fluids, feeding, safe effective medications that coat the GI tract to heal or prevent ulcers, an anti-vomiting/anti-nausea medication) and test their blood at the end of 2 days after the last medication to see if there are any signs of organ dysfunction. To err on the side of caution, I would continue treatment even if tests are normal and test again in 2 days and then if everything is normal and they are eating normally, I would say things will be ok.

You may have reached this time point already and if so, I hope your remaining kitties are doing fine. Please let us know.

I am SO sorry for your experience and your losses. I hope someone has informed the first vet of the consequences of what he did so that others are not harmed.

Thank you for writing.

Dr. Neely

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