I happened upon this forum using google. I have always used k9 advantage and advantage 2 for dogs on my cats also. Now the packaging says specifically do not use on cats. The ingredients are the same. Has there been a change in manufacture or are they just greedy?
The reason why you are seeing this warning is likely due to all the cat deaths from overdoses. My beloved cat died recently from Advantage II (seizures due to active ingredient poisoning her). When researching to figure out what went wrong I found lots of warnings about not letting your cat lick your dog that has been treated because cat livers cannot process the formula as well as dogs do. I do not have a dog, and all 3 of my cats got sick with my doing everything right (single dose, 1st dose of season, seperated cats till dry, on back of neck) so I am left with knowing that Advantage II flea treatment was not safe.