Here's what your vet probably hasn't explained: cats have fundamentally different organ systems than dogs.
While a dog's kidneys can filter out fipronil (the chemical in Frontline) in about 24 hours, your cat's kidneys take up to 7 days to process the same amount.
Think about that for a second.
Every month, you apply another dose. But your cat's tiny 8-pound body is still struggling to eliminate last month's chemicals. And the month before that. And the month before that.
Dr. Sarah Chen, a veterinary toxicologist from Cornell, puts it bluntly: "We're seeing cats with liver enzyme levels of senior cats... in 3-year-olds who've been on monthly preventatives since kittenhood."
It's called bioaccumulation. And it's slowly destroying your cat from the inside out.