Frontline Plus. Butter, (died earlier this year caught by a coyote), didn't have a reaction to the medication. Butter was 20 pounds; Betty was only 10 pounds. At the time I didn't realize her onset of problems came from the treatment. Apparently many pets, both dogs and cats, can suffer permanent damage or succumb to this and other topical flea treatments. Why aren't these pet meds taken off the market? They aren't meds, they are pesticides, that's why the EPA regulates them and not the FDA.
Previously the EPA advised manufacturers to change the products to be more weight specific but even with that there are still lots of pets who die from this treatment which is essentially a poison. The veterinarian also knew about the dangers of this product. I don't recommend using any topical flea treatments; it isn't worth the risk. It can cause severe skin irritation, liver and kidney failure, neurological problems, seizures, strokes, convulsions, and death. Sweet dreams Betty.