I have to agree with Chachi - there's been alot of really bad things that have happened with Hartz flea and tick products - I'd never use them - they've killed alot of cats and some dogs too
back 15 years ago - I had a cat and bathed him with hartz flea shampoo - I think I almost killed him - he foamed at the mouth for an hour and I had to rush him to the vet
They told me even back then the product is toxic