Ringworm, also called tinea, is a fungal skin infection of horses which causes hair loss and scaling in horses. It is often misdiagnosed when other more common skin conditions are present and yet is sometimes missed as a diagnosis when an atypical appearance presents. Fortunately most cases of ringworm are typical and by knowing the different clinical appearance of these similar diseases can often be diagnosed by appearance alone. This article discusses the appearance, diagnosis, treatment, prognosis, and prevention of ringworm.

Contact with infected horses and contaminated tack, bedding, brushes, and rugs are the source for this infection. The organism can persist in the environment for years unfortunately. Often ringworm occurs as a outbreak when young horses are grouped together in close confinement. Incubation time, the time from exposure till symptoms develop, for this disease ranges from less than a week up to 6 weeks. Following infection and as immunity develops to the organism recurrence is rare.