Selamectin (trade names Revolution, Stronghold) is a topical parasiticide and antihelminthic used on dogs and cats, distributed by Zoetis. It treats and prevents infections of heartworms, fleas, ear mites, sarcoptic mange (scabies), and certain types of ticks in dogs, and prevents heartworms, fleas, ear mites, hookworms, and roundworms in cats. 
Selamectin is a semi synthetic avermectin antiparasitic agent primarily used to kill adult fleas and ticks. It also kills ear mites, feline hookworms, feline roundworms and sarcoptic mange. It also prevents heartworm infection.
It works by interfering with the nervous system of insects and some worms, resulting in death.
Selamectin is a topical solution that collects in the oils of the skin and in the hair follicles. It is absorbed into the body and circulates through the blood stream.
The effects of selamectin last about 30 days.

Selamectin is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.