Which company markets Melarsomine as Immiticide in order to treat a small thread-like worm that causes filariasis in dogs, mainly, but also cats, ferrets, bears, sea lions, and coyotes?
Melarsomine:  In the U.S., it is marketed under the trade names "Immiticide" (Merial) and "Diroban" (Zoetis), and is approved by the FDA's Center for Veterinary Medicine for the treatment of adult heartworm ("Dirofilaria immitis") infection in dogs. Dirofilaria immitis:  The heartworm is a type of filarial worm, a small thread-like worm, that causes filariasis. Dirofilaria immitis:  The definitive host is the dog, but it can also infect cats, wolves, coyotes, jackals, foxes, and other animals, such as ferrets, bears, sea lions and even, under very rare circumstances, humans.
Merial