‘Scratches’ a common skin problem
Scratches, mud fever, and greasy heel are all familiar terms for pastern dermatitis, a common equine skin problem. Technically, pastern dermatitis is not a single disease but a generic skin reaction to a variety of causes. The skin irritation is most often visible at the back of the pasterns and heels, but can sometimes extend along the entire lower limb. Initially signs may be limited to redness and scaling, but they often progress to oozing of fluid (serum) from the skin, matting of hair, and development of crusts. Chronic cases can become very ugly indeed, as the skin becomes thickened and swollen. It may even develop bumpy, mass-like tissue. This condition is very painful for the horse, and can cause lameness in some cases.
Usually the condition is caused initially by something that irritates the lower legs including mites, allergies, flies, weeds, or long hair that remains wet. All of these factors irritate the skin and allow secondary infections to develop and scabs form. Your veterinarian may need to perform skin scrapings to check for mites as well as fungal and bacterial cultures to determine the type of infection.
Draft breeds are more susceptible to pastern dermatitis due to heavy feathering (longer hair coat at the pasterns). They are also more likely to have a mite infestation.
Regardless of the cause, treatment involves clipping all the hair off in the affected area and keeping it off until healing has occurred. An antibacterial shampoo with chlorhexidine can be used to carefully shampoo the area and soak the scabs until they can be removed without pain. Many of these horses need to be sedated to remove these scabs as the area is usually very sensitive. After scabs are removed, a combination ointment with antibiotics, antifungals, and cortisone daily with the leg under a wrap can be used until the infection is under control.
Wrapping daily with a combination of silvadine (anti-bacterial/anti-fungal) and triamcinolone (cortisone) cream seems to work extremely well for the cases that do not have mites involved.
Pastern dermatitis can be a debilitating condition for horses. Correct diagnosis early in the course of disease can greatly expedite its resolution, and most horses will have a full recovery.
Dr. Darin Peterson, DVM, was born and raised on a horse and cattle ranch in Rosholt, S.D., and received his B.S. in Animal Science from SDSU. He concentrates most of his work time with large animals. He can be reached at 701-347-5496 or email@example.com.