Horses and Ringworm

Ringworm, also called dermatophytosis, is a highly contagious skin infection that can affect horses that share grooming equipment, tack and blankets, or that live in damp, crowded barns. Although any horse can contract ringworm, elderly and young horses are more at risk since their immune systems are weaker. Ringworm gets its name from the raised circular patch that appears on the skin. It is in fact a fungus, not a worm.

  1. Spread of Ringworm

    • Dermatophyte spores live for many years in the environment and once a horse comes into contact with the spore, an infection can occur. Since the infected horse continually sheds infected hairs, it is easier for other horses to contract the skin infection. Some horses do not show any signs of ringworm, but as the spores are released into the environment and equipment is shared, other horses may contract ringworm quickly.

    Symptoms

    • Circular patches usually appear on a horse's back and stomach. It then can spread to the legs and face, notably the eyes. The skin becomes scabby and flaky; eventually the affected areas become bald and turn into blisters. The raised area resembles the shape of a worm beneath the skin, and these patches can be prone to other infections.

    Diagnosis

    • Sometimes signs of ringworm are not readily detected and some testing has to be done. Wood’s light, or ultraviolet radiation, tests for fluorescence, which some fungi reacts to, but further testing is usually needed. A microscopic exam may be done to inspect hairs for spores. A fungal culture can be performed in which hairs and skin cells are sampled and the growth of a ringworm fungi is attempted. While this test identifies the species of the fungus, it takes about 10 days to complete the growth process. A skin biopsy can be performed when lesions are uncharacteristic; this test accurately identifies fungal spores.

    Treatment

    • If a horse is thought to have ringworm, it should be isolated from other horses until a veterinarian can make a proper diagnosis and recommend treatment. Typical treatment includes bathing a horse with a shampoo containing Miconazole, an anti-fungal agent used in many human medicines to treat skin infections. The horse should be bathed with this shampoo every day for a week, then once a week thereafter until the patches are fully healed.

    Warnings

    • Because of the highly contagious nature of ringworm--not only to horses, but also to humans--it is important to take all necessary safety precautions. A bleach-and-water mixture can be used to purify grooming equipment, tack and any other shared items. Wearing gloves while bathing and handling the horse will help prevent the transfer of the fungus to humans.