MelarsomineDose, contraindications and adverse effects for Dogs.

Organoarsenical adulticide; the only approved drug for killing adult heartworms (Dirofilaria immitis) in dogs. Melarsomine is indicated for the treatment of stabilized class 1 (mild), class 2 (moderate), and class 3 (severe) heartworm disease caused by immature (4-month-old juvenile adults) to mature adult infections of Dirofilaria immitis in dogs. The American Heartworm Society recommends that a 3-dose melarsomine protocol should be used. Prior to melarsomine treatment, it is recommended to administer d

Although melarsomine is an arsenical compound, its exact mechanism of action is not known. Both laboratory and field studies have demonstrated that melarsomine is 90% to 99% effective in killing adult and L5 larvae of Dirofilaria immitis in dogs at recommended dosages. The 2-dose method kills only ≈90% of adult worms whereas the 3-dose method kills 98%.2,6

Melarsomine is contraindicated in dogs with class 4 (caval syndrome) heartworm disease. Caval syndrome is when adult heartworms are present in the venae cavae and right atrium. Do NOT give melarsomine IV or SC as significant toxicity or tissue damage may occur. Administer only by deep IM injection into the lumbar (L3-L5) epaxial muscles; do not administer at any other site. Dogs older than 8 years may be more susceptible to adverse effects than younger dogs.

Approximately ⅓ of dogs show signs of injection site reactions (pain, swelling, tenderness, reluctance to move) after receiving melarsomine, typically occurring within the first week after injection. This can be minimized by ensuring the injection is deposited deep into the belly of the epaxial musculature, with a needle newly changed after the drug is drawn into the syringe and that is an appropriate length and gauge for the size of dog and body condition.

■ Adverse effects including signs of thromboembolism (eg, low-grade fever, cough, hemoptysis, exacerbation of right-sided heart failure) ■ Cardiac biomarkers (cardiac troponin I, MB isoenzyme of creatine kinase, myoglobin) may be useful to monitor the effects of worms and adulticide treatment on…