Can my Cat Take my Dog's Medicine?
photo 2010 Keith Ramsey | more info (via: Wylio)
Can a worm medicine used to treat dogs be used for cats? I use Hartz dewormer on my dogs (Chihuahuas). My cat definitely has worms but don't have the cat dewormer on hand.
I don't recommend it.
Many deworming medications are used both in cats and dogs. However, I absolutely never recommend self medicating a pet. There are too many ways to go wrong.
Cats have unique metabolisms. They require lower doses of many medications, and they are more prone to toxic reactions than their canine counterparts -- including dogs that are cat-sized.
Also, you have mentioned the dreaded H-word. I have seen Hartz flea products cause so many toxic reactions that I suspect I will be forever prejudiced against the company's entire product line. I don't know what ingredients are in your particular Hartz canine dewormer, but I'd recommend that you throw that product away right now and call your vet.
Safe deworming is best done under the supervision of a veterinarian. Don't take chances -- get a prescription from him or her.