Dirofilaria repens is a filarial parasite of canids transmitting by mosquitoes. Besides, adult worms mainly exist in the subcutaneous tissue of dogs. And it deposits microfilariae that circulate in the blood.
Infections with D. repens always associates with skin swelling and hyperpigmentation, sub-cutaneous granulomas containing adult worms.
Additionally, although canids are final hosts of D. repens, it also infects people. The and aberrant migration of the worm can cause sub-cutaneous, conjunctival, and pulmonary nodules.

Melarsomine is a trivalent arsenical compound used as an adulticide.

Previously, Melarsomine and Doramectin are commonly used for the treatment of other helminth infections in the dog. But Melarsomine combines with Doramectin managed to clear the D. repens infection.
Besides, the initial Melarsomine treatment leads to lowering the number of microfilariae to 40% of their pre-treatment number. Additional Doramectin injection eliminates all remaining circulating microfilariae.
As a result, as a dosage of 2.5 mg/kg, Melarsomine combined with Doramectin manages to clear the D. repens infection in dogs.
Additionally, Melarsomine can cure T. evansi infection in camels. Intramuscular injection of Melarsomine can cure T. evansi infection in dairy cattle in Thailand. Melarsomine can be used for the research of canine heartworm disease and other helminth infections.

Arsenical treatment with Melarsomine has been the basis for heartworm (HW) adulticidal therapy. And directed Melarsomine is more effective, less toxic, and exhibits fewer complications than the historical arsenical, sodium caparsolate.

In conclusion, Adulticide treatment is essential to preventing disease transmission and progression. Melarsomine treatment can quickly eliminate the progression of the disease. What’s more, Melarsomine can kill more than 98 percent of worms in a known and controlled period of time.


[1]. Baneth G, et, al. Vet Parasitol. 2002 Apr 30;105(2):173-8.

[2]. Desquesnes M, et, al. Parasitology. 2011 Aug;138(9):1134-42.