My vet suggested that I give my two Shih-poo puppies Heartgard as a preventative measure against heartworm.  Well, like anyone who treats their dogs like their kids, I did my due diligence.  Just so you all know:

Most veterinarians will recommend giving a daily or monthly pill to prevent heartworms, but in actuality you are administering a drug on a regular basis that is designed to stop the baby heartworm - "microfilariae" from becoming adults. The most popular heartworm preventives, Heartgard and Interceptor, are not really preventives at all; rather they act by killing the microfilariae larvae...