This is totally my opinion, but I will not buy ANY Hartz products. When I was younger, my mom used their flea treatment on our dog who got a nasty chemical burn on his neck. One month later he started seizuring and eventually was put down because the seizures happened one right after another, and they couldnt stop it.
I was young, and Im not saying that Hartz caused this, but I wont take my chances. And I wont support their company by buying any of their products.
Have you seen this website?
http://www.hartzvictims.org/