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Leroy, a 3-year-old goldendoodle, was medicated and had his neck shaved after he had a reaction to a topical flea-prevention medication. Photo by Jean Lange-Mollmann

A reader sent us a note about her 3-year goldendoodle, named Leroy. To help prevent fleas, his owners purchased an over-the-counter, topical flea-control medication and administered it on the top of the dog’s neck as indicated on the package. The next day Leroy was noticeably uncomfortable and having trouble staying still. Within a week, the dog had developed bloody lesions on the neck site and was clearly in pain. They took him to the vet, and he had to be sedated so the flea-control medication could be scrubbed off. The dog was put on antibiotics, pain killers and steroids, his owners said, and he recovered in about two weeks.


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Veterinarian Jeffrey F. Duke, left, and Christina Karimi-Naser, a vet technician, below, from Pilchuck Veterinary hospital in Snohomish answer today’s questions about flea control.

Question: Are any over-the-counter flea-prevention meds safe on dogs and cats? Are they species-specific? Do dog products only work on dogs and cat products on cats?

Answer: There are a multitude of over-the-counter flea products available for dogs and cats. Most, however, are insecticides (a type of pesticide) that can be toxic for your dog or cat.

Pesticides are designed to damage the nerve system of insects, and will have a similar effect on mammals, sometimes leading to convulsions and seizures. Less serious toxicities may be seen, such as vomiting, diarrhea and weakness.

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Cats tend to be much more sensitive to pesticides. By far, the worst reaction we see is when a product intended for use in dogs is applied — even in small amounts — to cats. These pets often arrive at our emergency facility unconscious, hyperthermic and having seizures, and end up in intensive care, sometimes for days, to recover.

Fortunately, effective flea control has evolved greatly over the years, and we now can avoid using pesticides on our pets, in our homes and in our yards.

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