In today's VETgirl online veterinary continuing education podcast, we review the American Heartworm Society (AHS) heartworm treatment protocol used in dogs in a recent study by Romito et al. entitled “Efficacy and tolerability of the American Heartworm Society therapeutic protocol in dogs affected by heartworm disease without caval syndrome.” Heartworm, Dirofilaria immitis, is one of the most common and important parasites in dogs, but also affects cats, as well as a myriad of other animals, including ferrets. This disease is totally preventable with the regular administration of macrocyclic lactone drugs; however, not every animal gets these preventives.