Changes

==Treatment==

==Treatment==

Animals with right-sided congestive heart failure require stablisation with diuretics, ACE inhibitors and cage rest before treatment for heartworm disease is implemented. Animals with severe respiratory signs also require stabilisation with oxygen supplementation, anti-inflammatory doses of corticosteroid and anti-thrombotic drugs.  

Animals with right-sided congestive heart failure require stablisation with diuretics, ACE inhibitors and cage rest before treatment for heartworm disease is implemented. Animals with severe respiratory signs also require stabilisation with oxygen supplementation, anti-inflammatory doses of corticosteroid and anti-thrombotic drugs.  

The specific adulticidal treatment for ''Dirofilaria immitis'' is melarsomine dihydrochoride, a new generation arsenical compound. Melarsomine is administered intramuscularly into the epaxial muscles, and pressure should be applied during and after needle withdrawal³. A "graded-kill" protocol is recommended: an initial injection is followed one month later with two injections at an interval of 24 hours, given on opposite sides^1-4. This spreads the killing effects over two treatments, with an aim to reducing the occurence of thromboembolism after parasite death. Cage rest and anti-inflammatory doses of corticosteroids in the week following melarsomine treatment can also reduce the likelihood of pulmonary thromboembolism. Antigen testing four months after adulticidal treatment will determine whether it is necessary to repeat the therapy³.

The specific adulticidal treatment for ''Dirofilaria immitis'' is '''melarsomine dihydrochoride''', a new generation arsenical compound. Melarsomine is administered intramuscularly into the epaxial muscles, and pressure should be applied during and after needle withdrawal³. A "graded-kill" protocol is recommended: an initial injection is followed one month later with two injections at an interval of 24 hours, given on opposite sides^1-4. This spreads the killing effects over two treatments, with an aim to reducing the occurrence of thromboembolism after parasite death. Cage rest and anti-inflammatory doses of corticosteroids in the week following melarsomine treatment can also reduce the likelihood of pulmonary thromboembolism. Antigen testing four months after adulticidal treatment will determine whether it is necessary to repeat the therapy³.

Adulticidal treatment may be declined by the owner, owing to the risk of thromboembolism. Alternatively, it may not be possible to implement adulticidal treatment if the patient is suffering renal or hepatic failure³. In these cases, monthly administration of prophylactic doses of ivermectin is a reasonable treatment option, as it prevents further infection and may kill some adult nematodes².

Adulticidal treatment may be declined by the owner, owing to the risk of thromboembolism. Alternatively, it may not be possible to implement adulticidal treatment if the patient is suffering renal or hepatic failure³. In these cases, monthly administration of prophylactic doses of ivermectin is a reasonable treatment option, as it prevents further infection and may kill some adult nematodes².

Even low grade infections in cats may result in pulmonary thromboembolism with adulticidal treatment. Because of this, symptomatic treatment of sick cats may be followed by surgical or catheter-based extraction of nematodes once the patient is stable³. Stablisation is similar to that for feline asthma, and can include cage rest, oxygen supplementation, bronchodilators (e.g. theophylline), tapering doses of prednisolone, and balanced fluid therapy if indicated³. Heartworms have a much shorter life-span in cats, and spontaneous remission is seen in some cases. Regular monitoring may therefore be the best course of action in clinically well cats.

Even low grade infections in cats may result in pulmonary thromboembolism with adulticidal treatment. Because of this, symptomatic treatment of sick cats may be followed by surgical or catheter-based extraction of nematodes once the patient is stable³. Stablisation is similar to that for feline asthma, and can include cage rest, oxygen supplementation, bronchodilators (e.g. theophylline), tapering doses of prednisolone, and balanced fluid therapy if indicated³. Heartworms have a much shorter life-span in cats, and spontaneous remission is seen in some cases. Regular monitoring may therefore be the best course of action in clinically well cats.

In caval syndrome, surgery is the treatment of choice. Worms are removed from the right side of the heart and the main pulmonary artery using flexible crocodile or basket-type retrieval forceps². This procedure is complex and requires general anaesthesia and fluoroscopic imaging, but reduces the risk of thromboembolism following subsequent adulticidal treatment. Symptomatic and supportive therapy to stabilise the patient should be continued for around one month after surgery before adulticidal treatment is administered³.

In '''caval syndrome''', surgery is the treatment of choice. Worms are removed from the right side of the heart and the main pulmonary artery using flexible crocodile or basket-type retrieval forceps². This procedure is complex and requires general anaesthesia and fluoroscopic imaging, but reduces the risk of thromboembolism following subsequent adulticidal treatment. Symptomatic and supportive therapy to stabilise the patient should be continued for around one month after surgery before adulticidal treatment is administered³.

No drugs are specifically approved for microfilaricidal treatment of ''Dirofilaria immitis'', and successful elimination of adult worms should result in the demise of circulating microfilariae four to six weeks later². Single doses of ivermectin, milbemycin oxime, moxidection or selamectin are, however, effective at removing microfilariae from the circulation. The sudden death of large numbers of microfilariae may invoke an anaphylactic response, and oral prednisolone may be administered with microfilaricides to help prevent this.

'''No drugs are specifically approved for microfilaricidal treatment''' of ''Dirofilaria immitis'', and successful elimination of adult worms should result in the demise of circulating microfilariae four to six weeks later². '''Single doses of ivermectin, milbemycin oxime, moxidection or selamectin''' are, however, effective at removing microfilariae from the circulation. The sudden death of large numbers of microfilariae may invoke an anaphylactic response, and oral prednisolone may be administered with microfilaricides to help prevent this.

   

   

Heartworm prophylaxis should be implemented in all cats and dogs living in or visiting areas in which ''Dirofilaria immitis'' is endemic. Ivermectin or milbemycin oxime can be given ''per os'' on a monthly basis, and selemectin spot-on is effective when applied each month. If animals have already been exposed to ''Dirofilaria immitis'' it may be wise to perform an antigen test before starting treatment. In endemic countries, routine antigen testing six months after the end of the previous heartworm season will detect infections that have slipped through the net, and enable treatment during the mild, early stages of disease³.

Heartworm prophylaxis should be implemented in all cats and dogs living in or visiting areas in which ''Dirofilaria immitis'' is endemic. Ivermectin or milbemycin oxime can be given ''per os'' on a monthly basis, and selemectin spot-on is effective when applied each month. If animals have already been exposed to ''Dirofilaria immitis'' it may be wise to perform an antigen test before starting treatment. In endemic countries, routine antigen testing six months after the end of the previous heartworm season will detect infections that have slipped through the net, and enable treatment during the mild, early stages of disease³.