My perfectly healthy 1 year old cat was almost killed by this product. I applied it and immediately he began shaking his head. He tried to run away but fell over and started foaming from mouth and his nose. It appeared to have blood mixed in with it. I called the emergency vet who said wash it off with dawn dish soap. He was poisoned within minutes of applying. He recovered but it took a couple if weeks for him to bounce back to his normal self and that was only having it on him for less than 5 minutes. Never used any hartz product since.