Selamectin is a a broad-spectrum endectocide (a drug effective against both endoparasites and ectoparasites) that has been shown to be effective for the treatment of fleas, ear mites, scabies, ticks, some intestinal worms, and prevention of heartworms without toxicity in Collies.

Drug Classification

Selamectin belongs to the group of drugs called macrocyclic lactones which consists of two major groups: avermectins and milbemycins. The avermectins include ivermectin, eprinomectin, doramectin, and selamectin.5

Selamectin is produced as a fermentation product of Streptomyces avermitilis which is then chemically modified. The approved topical dose is a minimum 6.2 mg/kg for dogs and is 6.6 mg/kg for cats. Extensive studies have proved the drug's efficacy against heartworms, even when application was followed by bathing. The bathing study demonstrated that the topical application is not likely to be dislodged by inadvertent swimming or rainstorm.4

Selamectin is the first FDA-approved product that prevents heartworm disease.1 Oral application of selamectin prevents heartworm disease in dogs by activity against immature, larval stage of D. immitis, or eliminates naturally acquired infections of GI nematodes (A. caninum, U. stenocephalia, A. tubaeforme, T. canis, T. leonina, T. cati).2 In cats, it is also effective in the treatment and control of hookworms, A. tubaeforme and roundworms.

Heartworm Disease

There are a number of drugs currently in use as heartworm preventive. They include ivermectin (Ivomec, Heartguard), milbemycin oxime (Interceptor), and selamectin (Revolution). Heartguard is an effective preventive that is given once a month. It has the advantage that dogs do not have to be heartworm-free to initiate therapy. Interceptor is another once-a-month heartworm preventive that also acts on larvae. This drug is safer to use on Collies and Collie crosses. Selamectin is a once-a-month liquid preventive applied to the skin of the dog's neck between the shoulder blades. A principal advantage of selamectin that it also controls adult fleas and prevents flea eggs from hatching for one month. In addition, it treats ear mites and mites that cause scabies.3

Side Effects

When used according to manufacturer's directions, selamectin is safe in ivermectin-sensitive dogs, in breeding animals, and in puppies and kittens 6 weeks of age or older. Occasional local reaction (inflammation, alopecia) are seen following topical application of selamectin.1


  1. Muller & Kirk's small animal dermatology. George H. Muller, Danny W. Scott, Robert Warren Kirk, William Howard Miller, Craig E. Griffin
  2. Encyclopedic reference of parasitology. Heinz Mehlhorn, Philip M. Armstrong
  3. Dog Owner's Home Veterinary Handbook. Debra M. Eldredge, Liisa D. Carlson, Delbert G. Carlson, James M. Giffin
  4. Small animal clinical pharmacology and therapeutics. Dawn Merton Boothe
  5. Veterinary Pharmacology and Therapeutics. Jim E. Riviere, Mark G. Papich