April showers might bring May flowers, but they can also lead to skin problems such as scratches. Also called pastern dermatitis, dew poisoning, greasy heel, or mud fever, scratches is not a condition itself; it’s a description of a problem commonly seen on a horse’s lower limbs. Scratches is caused by a variety of skin conditions including viral, bacterial, fungal, or parasitic infections. Horses in excessively wet or muddy environments are at greater risk of getting scratches.
What Is It?
According to The Merck Veterinary Manual: “Scratches is a chronic, seborrheic (flaky skin) dermatitis characterized by hypertrophy (enlargement of the skin cells) and exudation (oozing) on the caudal (rear) surface of the pastern and fetlock. It often is associated with poor stable hygiene, but no specific cause is known. Heavy horses are particularly susceptible (potentially because their feathered legs can trap dirt and moisture), and the hind limbs are affected more commonly.”
It has also been noted that horses with light-colored legs or white socks are more susceptible to getting scratches.
What Causes Scratches?
“Constant moisture can become an irritant as it penetrates delicate skin, causing inflammation, redness, and ulcerations,” says Christie Ward, DVM, MVSc, PhD, Dipl. ACVIM, a specialist in internal medicine at the University of Minnesota Equine Center. “When coupled with muddy or dirty surroundings, it can be an ideal situation for invasion of bacteria and fungi. Mild cases are usually amenable to simple cleaning and topical treatment. In severe cases, or if the leg becomes hot, swollen, and painful, it is a sign that the infection has become more serious. In such cases, it is important to consult with your veterinarian.”
The first step in treatment is removing the horse from the wet or muddy environment. Any treatment will be practically worthless if the affected area remains damp and dirty.
Next, clip the hair surrounding the affected area. This will help keep it clean and dry and allow you to apply medication to the skin. Wash the area thoroughly using an antibacterial soap such as a Betadine scrub. Be careful when doing this because the area is likely sensitive, and if you scrub too hard, you could cause pain and potentially be kicked. Towel dry the cleaned area.
“If scabs are present, try to soak or sweat these off rather than picking them, which seems to aggravate the inflammation,” Ward says. “Limit your washing sessions to only once a day as additional moisture could further inflame the area.”
Ward recommends applying Corona ointment (containing lanolin) to the area to soften the granulomas (areas of infection due to tissue injury or infection) and help repel water. However, do not use ointment if the horse is turned out in a dry lot or muddy area because it will attract dirt.
“Severe cases often require topical treatment with cream that contains both antibiotics and antifungal agents and dexamethasone (a steroid) to reduce inflammation,” Ward says. “Really severe cases often benefit from a course of treatment with oral broad-spectrum antibiotics.”
Avoid keeping your horse in muddy or wet areas (this includes fields with tall grass during heavy rains or dew). Keep all boots or wraps clean. Be sure to check your horse’s legs regularly for any signs of redness, flakiness, or irritation, and begin treating the area as soon as you detect a problem. Pay extra attention to horses with feathered legs, since it can be harder to see the skin.