@justsaywhy Really?? I had to look it up, because I've never seen that happen in my 22 years in the field. We've always cautioned people whose dogs already had a history of seizures to not give Nexgard, but wow I had no idea it happened with Heartgard too. Are they by any chance in the collie family? Collies, Shelties, etc? I know those types of breeds are sensitive to ivermectin.