Catwoman wrote, “My vet said that the one difference in the two formulas is the specific anti-tick medication in the dog version.”
This simply isn’t true. There’s nothing in the dog version that’s not also in the cat version. Both contain fipronil and (S)-methoprene. Fipronil is just an insecticide—nothing fancy about that. It kills fleas & ticks.
But what about flea eggs that aren’t on your pet? That’s where methoprene comes in. It’s a synthetic JH (juvenile hormone) that mimics insects’ natural JH. In nature, JH allows larvae to grow bigger while preventing premature metamorphosis. When a larva gets big enough, it’s body stops producing JH, and the larva metamorphoses into a sexually mature adult, capable of reproduction.
Since methoprene acts just like real JH, the larvae just get bigger, but never become sexually mature, and can’t reproduce. They will die without ever laying eggs.
Frontline Plus for cats contains 9.8% fipronil and 11.8% (S)-methoprene (and 78.4% inert ingredients).
Frontline Plus for cats contains 9.8% fipronil and 8.8% (S)-methoprene (and 81.4% inert ingredients).
In other words, the dog and cat version are identical, except that the dog version has slightly LESS of one ingredient.
Lots of vets & shelters use the “dog” version of Frontline Plus on both dogs and cats.