Under the Skin

Ringworm, scratches and rain rot: While not serious ailments, these skin problems do require immediate care.

That an animal of such great power and strength should possess such extraordinarily sensitive skin remains one of nature’s many ironies. You only need watch as a horse will twist into a pretzel while balancing precariously on three legs to appreciate the great lengths it will go to remove a fly from the tip of its ear.

The largest organ of the body, the skin functions as an integral part of horse health. Yet because the dermis—or the live portion of the skin, which contains the nerve endings, hair follicles, blood vessels, and sweat glands, is covered only by hair and the epidermis, a thin dried layer of cells—it is particularly susceptible to a host of irritants. A number of situations, from dirty bedding to sunburn, can upset this fragile layer, resulting in a variety of conditions that may be particularly frustrating to diagnose and difficult to treat.

While volumes have been researched and written on the subject, outlined below are three common conditions horses are most liable to encounter while on your watch. If you’re able to catch and define them early enough, you can often administer treatment yourself. But it’s still a good idea to call your veterinarian to get his or her recommendation, as several, more serious diseases exhibit similar symptoms.

Dermatophytosis (Ringworm)

Defined: Contrary to its common name, ringworm is not a worm but a fungal infection. It assumes the form of round, crusty patches which, when removed, leave reddened scaly skin and hair that falls out in clumps. It usually first appears around areas where tack comes into contact with the skin, although the disease can be found anywhere on the body. Highly contagious, ringworm can be transmitted directly from horse to horse, or through inter-species contamination; dogs, cats, cattle, and even people are often the carriers. It also can adhere to inanimate objects such as tack, blankets or grooming equipment. And with the spores remaining dormant in the environment for up to a year, everything from your stall and barn to the soil in your paddock can become infected.

Like all fungi, ringworm is most receptive to dark, warm, moist conditions. Therefore outbreaks generally occur in the fall and winter months, when there is less sunshine and more moisture. However, horses that are debilitated from an illness, are undernourished, are in stressful surroundings, are on immune-suppressing medications, or are in an overcrowded situation are especially vulnerable.


• Isolate your horse as best as you can before you begin treatment. Call your veterinarian to make sure you’ve made the right diagnosis and have the appropriate medications to treat it.

• Start by clipping about a two-inch portion of hair around each outbreak, so that medicated shampoo and cream will be sure to penetrate that portion of skin most likely to become affected before the fungus is contained.

• Wash your horse with an anti-fungal shampoo intended specifically to treat ringworm. Your tack shop will probably have several on hand, or you can get one from your veterinarian. There are also a variety of topical ointments that can be applied to the infected spots. Be sure to wear latex gloves or, at the very least, wash your hands after each treatment.

• Clean your tack and equipment with a disinfectant soap in combination with a leather conditioner to keep it soft. If possible, get it out in the sunshine—a sure remedy.

• Disinfect your blankets, saddle pads, and grooming tools. Chlorine bleach is an effective neutralizer, but it is extremely abrasive to healthy skin tissue, so be sure to rinse everything thoroughly.

• Sanitize your wash stall, box or standing stall, cross-ties, fences, posts, and wooden gates. Anything that has come into contact with the fungus is a potential carrier.

Prognosis: In most instances, ringworm is self-limiting and will disappear on its own within six weeks to three months. Acute infections may require prolonged treatment or reassessment via skin culture, cytology, or biopsy to make sure there is no other underlying problem. Whatever the severity of the case, know that ringworm is a distressing ailment and should be treated to control its spread and timeline.

Dermatophilosis (Rain Rot/Scald)

Defined: Dermatophilosis, rain rot or rain scald is a bacterial infection. Like its fungal counterpart, ringworm, it lives in soil, and can inhabit the skin without adverse effect until there is either trauma or repeated exposure to moisture. Horses kept outside where they are fending off insect bites or are left to stand unprotected in the rain are prime targets. Like ringworm, rain rot is more apt to appear in the fall and winter months, and like ringworm, rain rot is believed to be contagious.

Infected horses typically develop a series of small bumps that progress into circular scabs with matted tufts of hair, which are quite painful when removed. Lesions are commonly found along the back, rump, neck, and legs.


• Horses with rain rot should be kept dry and away from biting insects.

• Begin a seven- to ten-day cleansing program with a medicated shampoo. Because the bacteria live under the scabs, these should be detached during the bath when they are soft, to spare your horse further discomfort.

• Penicillin injections, administered by your veterinarian, can expedite the healing process, especially if rain rot is detected early.


• Although thought to be transmitted through shared tack, blankets, and grooming equipment, anything that has come into contact with the affected horse needs to be disinfected.

Prognosis: A self-limiting condition, rain rot can resolve itself spontaneously once the immune system gets going or when the weather becomes drier; however, the disease can become quite acute before it improves. To prevent further occurrences, avoid having your horse outside during inclement weather without shelter, protect it against fly bites, and maintain good grooming habits.

Dermatitis (Scratches)

Defined: Dermatitis, also known as mud fever, greasy heel, dew poisoning, or scratches, affects the backs of the pasterns and the bulbs of the heels and is most commonly found in horses who are exposed to moisture for long periods of time, whether from standing in a muddy field or a wet stall. Constant moisture can become an irritant as it penetrates delicate skin, causing inflammation, redness, and ulcerations. When these factors are coupled with dirty surroundings, infection becomes almost inevitable. Scratches is not a disease unto itself, but stems from a variety of microorganisms including bacteria, fungus and parasites, as well as allergies.


• Speed is of the essence when tending to scratches. Left untreated, the raw skin can crack and bleed, inviting a deeper level of infection.

• Consult with your veterinarian, who may want to do some laboratory work in order to make the correct diagnosis and treatment recommendation before you take action that possibly could delay or even complicate the healing process. If the leg or legs should become hot and swollen, it is a sign that the infection has become more serious, in which case your veterinarian may need to prescribe specific medication.

• Regardless of the cause, there are several steps that should be taken when dealing with scratches. Start by clipping the long hair from the affected skin, to keep it clean and dry.

• Next, wash the area thoroughly but gently. Make sure to remove dirt but be careful not to aggravate the skin. Then, lightly towel-dry the area. Limit your washing sessions to once a day, as additional moisture could further inflame already tender tissue.

• Also, try to keep your horse out of muddy or wet places, and make sure that its bedding is clean and dry.

Prognosis: Avoid hosing your horse’s fetlocks and pasterns unless you have a specific reason, and always make sure to completely dry the area afterward.

Summing it Up

With prompt attention and care, most skin problems can be resolved successfully. As with any health issue, if you have a question, whether about a lump, a bump, or a sore, it’s a good idea to get in touch with your veterinarian who can identify the condition and prescribe the appropriate treatment plan.






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