What is Ringworm?
Dermatophytosis, also known as ringworm, is one of the most common skin issues that affect horses. Higher incidents are seen more frequently in hot, humid climates but can be seen in colder, dryer climates. It can occur at any time of the year but more frequently seen in the warmer months. It has a unique appearance of circular lesions with a crusty layer of buildup and hair loss in the area. Ringworm is not caused by a worm but by a fungus. There are antifungal medications you can get from your veterinarian once a diagnosis is confirmed. Prognosis of recovery is drawn out, but good.
Ringworm can affect horses in any environment, any age, and at any place on the body. It is known by appearance of circular, crusty lesions located anywhere. Variable degrees of pain are seen with ringworm so treatment should be started as soon as possible to offer your horse relief.
Book First Walk Free!
Symptoms of Ringworm in Horses
Symptoms you may see in your horse include:
- Ring-shaped lesion (although it can appear in other shapes too)
- Round, bald patches
- Affected skin dry and scaly
- Size of lesions vary
- Usually not associated with itchiness
There are 2 types of fungi that can cause ringworm in horses: Microsporum and Trichophyton. Both of these infect the skin and the hair. The incubation period is long compared to other organisms; it can be months from when the spore is deposited on your horse’s skin before symptoms may appear.
Causes of Ringworm in Horses
For ringworm to infect the skin, the skin has to be damaged or rubbed to allow the fungi to make it past the protective layer of skin. The fungus weakens the base of the hair shafts causing the hairs to break off. The fungi produce spores resistant to environmental conditions making them very difficult to get rid of. They can remain in the area for months to years and cause re-infection of the same horse or others as well. Spores can survive in and on many type materials including in the stable and on fencing.
Diagnosis of Ringworm in Horses
While it can affect any aged horse, it is more commonly seen young horses under the age of 5. Older horses usually develop immunity to ringworm but infection can occur. Ringworm is not necessarily itchy or sore despite its scaly, thickened appearance. Lesions appear with a characteristic look of circular patches of hair loss and skin change. Lesions are most commonly seen where the tack rubs and at the saddle and girth areas, but also on the face.
By physical examination alone, your veterinarian will have a good idea if your horse is suffering from ringworm or not. However, for a definitive diagnosis, she may want to perform a DTM culture. Dermatophyte Test Medium (DTM) is a selective medium used to grow and isolate pathogenic deratopytic fungi, such as the ones that cause ringworm. The veterinarian will collect a sample from the suspected area on your horse and apply it to the culture. Cultivation of the fungi on the medium can take up to 14 days. If there is no growth after the allotted time, then it is considered negative for ringworm.
Treatment of Ringworm in Horses
There are multiple options for treating ringworm in horses. Your horse’s sex, breed, age, and pregnancy status will be considered by your veterinarian when she is choosing a course of treatment. Since the fungi do infect the skin, she may prescribe oral antibiotics. However, some antibiotics cannot be given to pregnant mares so other options may need to be considered.
Treatment topically is beneficial since fungi also affect the superficial layer of skin and hair. Medicated shampoo and sprays with antifungal medications in them are helpful. In some cases, a secondary bacterial infection will develop and will also need to be treated.
Your horse’s environment should also be treated for ringworm. Disinfectants should be used in and around his stall and your stable. Be sure to also clean his tack and grooming kit and anything else you may use on him. Ringworm can be spread by direct contact so you should keep your infected horse away from the others. Also, if putting outside, keep him in an area he can be quarantined to.
Recovery of Ringworm in Horses
Ringworm is zoonotic, meaning you can contract it from your horse. When treating him and dealing with him in any manner, be sure to clean your personal protective equipment and employ appropriate hygiene habits.
Getting rid of ringworm can be a long process but it is necessary for the health of you and your horse. The lesions may take a while to heal even after it is no longer considered contagious. The skin has to clear and the hair has to regrow meaning it can take weeks to months. While it may not look pretty, just know your horse is on the mend and considered healthy.