Thanks for your reply. Actually, Sugar IS the dog's name...mine is Sheila. Sugar weighs 26.5 pounds and the vet gave her the Interceptor for dogs 26 - 40 pounds in weight. I thought it was strange that he didn't give her the same dosage as my older sheltie who weighs 24 pounds, but I trusted his expertise and gave her the pill. I know you can't make conclusions from just one case, but I'll always think that had he given her the smaller dose, this might not have happened. Sheila