Help - I Just Put Dog Flea Control on my Cat

Mistakes Happen. Act Quickly. First Aid Tips and What to Watch For.

Small cat licking large dog.
Chuck Eckert / Getty Images

Fleas are the common enemy. Medications to kill fleas are toxic, and directions must be followed with care to avoid accidental pet poisoning. More isn't better.

Accidentally putting dog flea control (or the wrong dose) on a cat happens, though, and it is a frequent emergency question.

I asked veterinarian and veterinary toxicologist, Dr. Ahna Brutlag from the Pet Poison Helpline (PPH) for her insights on this problem of flea control toxicity in cats.

Is this type of poisoning a common call to poison centers such as PPH?

Yes, in fact, topical spot-on insecticides are the number one feline toxin reported to Pet Poison Helpline!

How are cats exposed to these products? Poisoning most often occurs when pet owners accidentally (or, sometimes, intentionally) apply dog-specific topical flea/tick products to their cats. Those products that contain insecticides from the pyrethrin or pyrethroid family are the culprit (e.g, permethrin, cyphenothrin, etc.). While these insecticides are safe for dogs (and people),  they are extremely toxic to cats because our feline friends lack the metabolic pathway to quickly detoxify these chemicals.

Dogs and people, on the other hand, are rarely poisoned by these chemicals. Cats can also be exposed by grooming a dog that recently had the product applied or, rarely, even licking the bedding of a dog following application.

Remember, cats are not just small dogs. It’s best to think of them as an alien life form that does not obey the rules of other mammals.

Related: More about pyrethroid toxicity, from Pet Poison Helpline. 

What is the first thing an owner should do upon realizing this mistake?

Generally speaking, if you notice your mistake within a few minutes of application, the best option is to immediately (and thoroughly) bathe your cat with liquid hand-dishwashing soap (e.g., Dawn).

I often recommend 2-3 latherings just to be safe.

If like me, you liken the idea of bathing your cat to wrestling an alligator, you’re better off bringing him/her straight to your vet for a thorough cleaning. There’s nothing worse than a half washed cat and an arm full of bite marks to ruin your day.

If you don’t notice your mistake until your kitty starts showing twitches or tremors, DO NOT BATHE! Bring your cat immediately to your vet instead. If you were to put a twitching/tremoring cat into the water, chances are that she will become so overstimulated that she’ll start to have seizures. Instead, your vet will sedate your cat, stop the tremors and then safely decontaminate her.

If you caught your mistake in time to safely bathe your cat, your next step is to monitor her very closely for at least 8-12 hours. By "monitoring very closely," I mean checking on her at least every 15 minutes. Set a timer and be diligent about this. Do go to a movie and leave her at home, do not go grocery shopping, do not go on an hour long run, and most important of all, do not go to bed!

We’ve had several occasions where pet owners thought they had thoroughly bathed their cat and, believing all was well, went to sleep for the night.

They then awoke to find  their kitty with severe tremors or seizing the next morning. These are terrifying situations and completely preventable. If you aren’t able to stay with your cat, bring her to your vet—they will be able to monitor her while you’re away and, should signs of poisoning arise, they can immediately begin treatment.

(Worthwhile tangent! Speaking of cat bites…if your cat ever breaks your skin when biting you, this is serious business and you need to call a doctor. Cats carry a particularly nasty bacteria in their mouths called Pasteurella multocida which is notorious for causing serious infection in people. As veterinarians, we’re all too familiar with this nasty bug. Often, the best practice following a cat bite is to thoroughly wash the bite site with soap and start a prophylactic course of antibiotics.

Also, it’s rarely recommended to have the bite site sutured shut for fear of "trapping" the bacteria in the wound. If your physician suggest stitches, make sure s/he is aware of this risk!)

Dawn is the brand most often mentioned for removal of oily residues (skunk, oil spills, toxins). Anything particular about this brand, or could any grease-cutting dish soap be used just as effectively?

Any liquid hand-dishwashing soap is fine with me. Do not use automatic dishwasher detergent, though. This is too strong and may cause chemical burns on your cat’s sensitive skin. 

What are the common clinical signs seen with topical flea medication overdose such as this case?

Concentrated pyrethroid or pyrethrin-based insecticides cause neurological stimulation in cats as evidenced by muscle twitches, tremors, and seizures. Often, these signs start within a few hours of application and can last for days and be fatal if left untreated.  

What clinical signs do you feel require a hospital visit or in-hospital monitoring?

If a cat starts to show muscle twitching, it’s time to get to the hospital. Mild twitching can quickly progress to serious tremors and seizures, both of which can be effectively treated by your veterinarian with injectable muscle relaxants.

Additionally, twitchy cats may have difficulty eating and drinking which can result in dehydration and, in severe situations, fatty liver disease (this can occur in cats, especially obese cats, that do not eat for more than 2-3 days). While these signs can be very serious or fatal, it’s important to know that these kitties have an excellent prognosis if treated quickly and appropriately. The drugs given to cats to combat this drug are safe and highly effective.

Thank you, Dr. Brutlag, for sharing your expertise on flea control toxicity in cats.