Q: I have a nine-pound cat named Beauty and a five-pound Chihuahua named Beast. Is it OK for me to apply half of Beast’s monthly flea and tick preventive to his skin and the other half to Beauty’s skin? That way, I could cut my monthly cost for flea/tick prevention in half.
A: It’s far safer to treat Beauty with a product labeled for cats because most topical flea and tick products for dogs contain substances toxic to cats.
The most common are pyrethroids, neurotoxins that paralyze and kill fleas, ticks, mites and lice. Pyrethroids are synthetic versions of pyrethrins, natural insecticides derived from chrysanthemums. Compared with pyrethrins, pyrethroids are more toxic, have a longer duration of action and are more stable in the environment….