I read in another post that Ivermectin is unsafe to use as a vermicide for cats. Does anyone have any information about this? I knlow that it has toxic affects in collies and collie crosses, but did not know about a problem with cats. During the winter a FERAL cat (as in wilder than the wild animals that frequent my backyard) took up residence beneath one of my pigeon lofts. She has since moved to a utility shed that she claims as home. She was in rough shape so I wormed her for tapeworms and then later I wormed her for roundworms with Ivermectin. I actually used a dose 2 X what I use on my dogs. She now looks in great shape as she streaks to the security of her shed. I am hoping that she (calico so pretty positive as to her sex) is the result of a trap/spay/release program. My vet will not spay her after an experience with a feral spay that exposed him and his staff to rabies. I'll cross that bridge when I get to it. For now, is Ivermectin toxic to cats?