I always get my dogs tested in the Spring for heartworm and give them Heartgard from June through November. But I have been reading of the side effects of Heartgard. The potential side effects of Ivermectin (the active ingredient in Heartgard) include liver problems, vomiting, diarrhea, loss of appetite, depression, lethargy, skin eruptions, seizures, tremors, paralysis, autoimmune disorders, thyroid problems, fever, weakness, dizziness, coughing, nose bleeds, difficulty breathing, pneumonia, irritability, sudden aggressive behavior, nerve damage, fertility problems, and sudden death. I know these side effects probably don't happen too often. Do you think the benefits of this treatment out weigh the side effects? I only started thinking about this because I have a sickly dog and don't want to put anymore strain on her liver by giving this. Do most of you give Heartgard to your pets?