what they are referring to in the heart guard and high dose is ivermectin as heart guard has ivermectin in it and why i like interceptor better for toy breeds from what i have read. Luckily in california we do not need heart worm prevention so i avoid that as well as flea protection but have read alot about the reactions of those two drugs. I would be very upset with your vet as everything i have read says 5lbs or more - time for a new vet |