Equine Dermatophytosis Study Guide

Overview and Clinical Importance

Dermatophytosis (commonly known as ringworm) is one of the most common superficial fungal skin diseases affecting horses worldwide. Despite its name, ringworm is not caused by a worm but by keratinophilic fungi that invade the stratum corneum and hair follicles. This condition is highly contagious among horses and represents a significant zoonotic risk to handlers and veterinary personnel.

Equine dermatophytosis is particularly important in practice because affected horses are prohibited from competitions, races, and international travel. The disease can spread rapidly through barns via shared tack and grooming equipment, causing significant economic losses and management challenges in training and breeding facilities.

Etiology

Causative Organisms

The primary causative agents of equine dermatophytosis are fungi belonging to the genera Trichophyton and Microsporum. These dermatophytes produce keratinases that enable invasion of keratin-containing structures.