I thought I was doing a good thing by putting Hartz Flea and Tick Drops on my cat and my dog (both adults) each month to prevent fleas. But it seems I was slowly killing them. My cat became sick first…he was lethargic and wouldn’t eat. Our Big, Beautiful 25 pound cat only weighed 10 pounds when we took him to the vet and was also very jaundiced. The vet told us that day that the flea drops were to blame for his liver damage. Within a week our happy-go-lucky dog started have seizures and was lethargic. Upon taking him to the vet he also had liver damage from the flea drops. The flea drops are the only thing in common that these 2 animals have. They do not eat the same food or even use the same shampoos. The flea medicine was only link between the two. Luckily after visiting the vet, being put on medicine, and spending a large amount of money, we caught it in time, they are both recovering nicely. But it could have easily turned out the other way!