answer:There is no alternative. Canine heartworms, if left untreated, will eventually cause death. There is no way to know how long an infected animal will live (a few months versus a few years), but they will definitely suffer a debilitating decline resulting in anorexia, ascites and heart failure. Treatment for heartworms involves killing the adult worms that are living in the heart chambers – this is a relatively dangerous time for the dog and he will need to be hospitalized for the duration of the treatment. As the worms die, they decay and pieces may circulate through the bloodstream, creating the potential for dangerous emboli. After successful treatment, he will need to return in a month for an injection that will kill any immature parasites circulating in his bloodstream. After treatment, give monthly heartworm protection to prevent a repeat infection. Having heartworms once will not prevent a reinfestation.