It is an alteternative that the AHS ( American heartworm Society) recommend only for dog in which an adulticide is too risky. It can take years for Ivermectin ( the only preventative nown to kill adults) to be effective It realy will only kill adults 7 month and younger but sterizes females so they can not reproduce and the older worms dies natural. It is posible for then worms if not treated with an adulticide to continue to do damage to the heart and lungs so the general recommendation is to use an adulticide to kill the worm in a two stage approach it minmize throbosies cause body the breakup and decay of dead heatworms when killed.There is a basset in a shelter who is hw positive. The dog appears to be an adult (5-7 maybe) - definitely not a senior nor a puppy.
The shetler is treating his hw by keeping him on preventative 12 months a year. They say this will kill the larva, stop the adults from reproducing and eventually kill off the adults. I don't know how severe his hw's are.
I've never heard of treating hw's like this. Is it an accepted treatment and is it easier on the dog? Also, can it be done for any hw infestation or would it just be used for a mild case?[/b]
see 2005 Guidelines For the Diagnosis, Prevention and Management of Heartworm (Dirofilaria immitis) Infection in Dogs
It May be beneficial to administer a macrocyclic lactone for up to six months prior to administration of melarsomine, when the clinical presentation does not demand immediate intervention. The reasoning for this approach is to reduce circulating microfilariae and kill migrating D. immitis larvae, and in the case of ivermectin, stunt immature D. immitis and reduce female worm mass by inhibiting the reproductive system. Milbemycin also sterilizes female worms, but it does not affect worms older than four months. Administration for greater than three months should result in reduced antigenic mass, which in turn may reduce the risk of pulmonary thromboembolism. Depending on the season and geographic locale, administration for three months also will allow immature worms to reach an age at which they are known to be susceptible to killing by melarsomine1.
...Continuous monthly administration of prophylactic doses of ivermectin, alone or in combination with pyrantel pamoate, is highly effective against late precardiac larvae and young (<7 month="month" post-infection))" adult heartworms. Comparable adulticide capability of the other macrocyclic lactones has not been reported. The adulticide effect of ivermectin generally requires more than a year of continuous monthly administrations and may take more than two years before heartworms are eliminate completely. The older the worms when first exposed to ivermectin, the slower they are to die In the meantime, the infection persists and continues to cause disease. Therefore, long-term continuous administration of ivermectin generally is not a substitute for conventional arsenical adulticide treatment. If arsenical therapy is declined, a lengthy course of prophylactic doses of ivermectin will gradually reduce the number of adult heartworms, but in chronic mature infections this may not be clinically beneficial. Exercise should be restricted in dogs treated with prophylactic doses of ivermectin as the adulticide.
The results of a recent study in which monthly ivermectin was administered to client-owned heartworm infected dogs for two years indicated that this method of killing adult heartworms should not be used in dogs with signs of heartworm disease or very active dogs, and if used in asymptomatic dogs, the dogs should be examined by a veterinarian at least once every four to six months until all of the worms are dead As worsening of radiographic signs may be observed, periodic radiographic evaluations may be useful in monitoring the treatment.[/b]