Common Equine Skin Lesions


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Let’s look at ringworm, mange, lice, and bacterial infections in horses.

The skin is the horse’s largest organ and creates the body’s protective barrier. Several common skin diseases can occur in horses.

“Most skin lesions are caused by hypersensitivity to insect bites and pests like biting midges; stable, horn or deer flies; and mosquitoes,” said Steve Graff, DVM, Professional Services Veterinarian at Dechra. “A lot has to do with environmental sanitation. Flies lay their eggs in the horse feces so manure removal needs to be done regularly.”

Insect bites can cause pruritus, or itchiness, leading horses to scratch themselves, stated Dr. Graff. This can result in further irritation and possibly infections. Graff shared some other common skin conditions that veterinarians may diagnose.

Ringworm is a type of fungal dermatitis that usually appears where contact has been made with infected equipment such as saddle pads, saddles or bridles. Small circular lesions, loss of hair, and itchiness are clinical signs. Ringworm is very contagious to other horses, animals, and humans. The lesions can be treated with topical shampoos and sprays with miconazole or chlorhexidine as an active ingredient. Equipment should be decontaminated between uses.

Mange is a common term for a mite infection, which usually manifests in cooler, wet conditions and is more common in the fall or winter. It can take place anywhere on the horse but is most common on the pastern region, commonly known as pastern dermatitis, scratches, or greasy heel. Diagnosis requires a deep skin scrape which is put on a clear glass slide and looked at under a microscope to confirm. Treatment typically consists of topical insecticide applications. Medicated shampoos are usually used to remove skin crusts as it is important to keep the area clean and dry.

A photo of a horse biting at lice on its back.

Lice are another common type of parasite. Infestations can occur all over the body including the mane, tail, and fetlocks. Horses with lice will show signs of itchiness by constantly rubbing and biting affected areas. It’s common for horses in poor body condition to have lice, which leads to further deterioration. Lice can occur more frequently in winter when hair coats are long. Treatment includes spray or rub-on insecticides.

Ran rot or rain scald is seen in wet, rainy areas and is typically a result of poor grooming and lack of sunlight. It manifests as crusty, oozy lesions across the top of the back that make the hair clump and stick together. The bacteria which causes this condition, Dermatiphilus congolensis, is very contagious to other horses. Usually, horse owners will treat the affected area by bathing with a 4% chlorhexidine antibacterial shampoo to loosen and remove the crusts. Allowing the skin to dry and using topical antibacterial sprays are suggested to help prevent relapse.

Graff recommends using commercially available topical medicated sprays and shampoos to help treat skin conditions diagnosed by a veterinarian. Dechra offers a complete line of shampoos and sprays for veterinary needs.

“Effective antifungal/antibacterial shampoos and sprays that contain miconazole and chlorhexidine are an integral part of managing common bacterial and fungal infections in our equine patients,” Dr. Graff said.

Photo credits: Khruscheva,