Winter Effects on Equine Skin & Hooves

October 11, 2016
By Richard G. Godbee, Ph.D., PAS, Dipl. ACAS-Nutrition


As the seasons change from summer to winter, many horse owners start to transition from daily riding to riding more as the weather suits. Horses that were groomed daily for riding may now only be groomed weekly, and often times, the duration of those grooming sessions will get shortened due to the cold and/or wet weather. Daily picking of a horse’s hooves may also shift to a weekly schedule, and horses that were kept in a barn may spend more time outside during the winter months. While these changes are not detrimental, horse owners will need to be more vigilant in observing changes that would have been noticed in those daily grooming sessions during the riding season.

Effects of moisture

In many parts of the country, the fall and winter seasons bring increased moisture in the form of rain or snow, which in turn creates a muddy mess that all horse owners are familiar with. The combination of too much moisture and mud, and a lack of consistent grooming, can lead to various skin and hoof conditions. Exposure to constant moisture, rainfall or humidity can result in more issues than sporadic downpours because the coat never has a chance to dry, leading to bacteria growth. For most horses, the skin and hair forms a protective “shield;” however, this shield can become compromised when the horse is exposed to excessive amounts of moisture, such as prolonged wetness and high humidity, or any factor that alters the skin’s integrity, like high temperatures or attacks by biting insects that leave an opening in the skin for bacteria to enter.

Common types of skin and hoof disorders

For horse owners living in areas with a lot of rain or humidity, skin and hoof conditions are unfortunately a part of having a horse. The skin is the largest organ of the body and is an integral part of a horse’s health, so it’s important to understand the different types of conditions that horses may encounter.

Rain Rot / Rain Scald

One of the most common skin disorders is Rain rot, a contagious, bacterial skin disorder that can be transferred to other horses by direct contact, as well as, shared grooming tools and tack. The hair on horses with rain rot has a paintbrush-like appearance (Figure 1) and is commonly found on the back, hindquarters (croup), back of pasterns and rear cannons. It is often worse in horses with white hair coats or light-skinned areas. Small dry lesions can be removed with routine grooming or bathing with an antimicrobial shampoo such as Horse Health™ Viodine® Medicated Shampoo, but removal of larger lesions with yellow-green or gray-colored pus can be painful and may require further intervention. In some closed barns during winter, the humidity can be very high and may increase the horse’s susceptibility to rain rot.

Scratches / Greasy Heel / Mud Fever / Dew Poisoning

Scratches or Pastern Dermatitis (Figure 2) is another skin condition related to excess moisture. Other names for this malady include mud fever, mud rash, greasy heel, dew poisoning and cracked heels. Like its multiple names, scratches may have a variety of causes. Exposure to wet, muddy, unsanitary conditions is the main culprit; however, other causes can include abrasions to the fetlock or pastern area, resulting in micro-trauma to the skin. Horses with feathering are also prime candidates for issues in this area due to moisture retention from a lack of air flow and shadowing from sunlight. Scratches can be identified by scabby, crusty lesions between the fetlock and the heel, most commonly on the hind legs. Crusts form from blood or serum seeping through the skin and the skin may be red, swollen and painful. A mild case of scratches is uncomfortable for the horse, but if left untreated, scratches may cause lameness, and secondary infections can become a concern. If a horse appears to have scratches, the first thing to do is to change his environment by moving him to a dry, clean area.


Thrush (Figure 3) is another issue often associated with a decrease in grooming and an increase in wet, muddy conditions. It is a hoof condition that affects the cleft or sulcus of the frog and is caused by anaerobic bacteria (bacteria suited for living in an environment without oxygen) that can result from inadequate removal of packed manure and mud. Thrush is characterized by a strong putrid odor, dark or black discharge and deep fissures extending to the heel bulbs. While all four feet may be affected, thrush is more often seen in the hind feet. Horses with contracted heels are also more prone to thrush, especially if shod.

While horse owners can’t control the weather, they can continue to provide adequate care and grooming during the off-season. Proper hygiene practice that includes a clean living environment and daily observation will help to minimize skin and hoof problems seen this winter.

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