Exudation from the skin, which causes matting of the hair and formation of crusts, is often due to infection. Common problems in winter and early spring include rain scald, mud fever and saddle rash. The most common places for these clinical signs (lesions) to develop are on the back and on the pastern. Most cases are due to bacterial infection, but some are the result of immune problems.

Rain scald is a very common condition caused by Dermatophilus congolensis. Skin wetting from rain, long dense hair coat and poor hygiene create an ideal environment for the bacteria to grow on the skin surface. If one horse is infected, others may become infected too. Scabs cause pain and discomfort, and removal of them is often resented and usually leaves a rosy-red area of skin. Treatment of rain scald involves keeping the skin dry after a careful warm water antibacterial wash. It is also important to avoid over-grooming while the skin heals; if the whole area can be clipped this will speed up the healing process. Rugs and blankets should be removed from the horse, as sweating without evaporation and extra warmth will simply encourage the bacteria! Some cases are very difficult to manage, sometimes requiring courses of antibiotics, and affected horses may get repeated episodes.

Saddle rash is normally caused by Staphylococcal infection. It is usually a painful dermatitis most often affecting the back, loins, withers and neck of the horse. It is common in late winter and early spring and usually caused by a break down of hygiene. The combination of a long winter coat, an emerging spring coat, heavy rugs, poor grooming and tack cleaning contribute to its development. There are several forms of the condition, including:

• Focal "acne-like" disease - pustules (spots) develop in the skin; there may be few or many lesions. 
• Widespread skin changes with oozing over the surface in some cases. 
• A milder form - where Staphylococcal bacteria gain entry to minor scratches (such as sweet itch rubs and tack abrasions, etc).

Once the condition starts it can be extremely painful; the horse may resent being handled or being washed. It is common for the affected areas to expand or seem to spread to other areas - this may be associated with the use of dirty brushes, rugs and other tack. In the same way it can spread to other horses. Diagnosis is usually simple - your vet should take material to examine under the microscope and a swab of the skin to identify what bacteria are present. Sometimes a skin biopsy has to be taken so that the bacterial swabs can be obtained from deep inside the skin.

Treatment is always difficult. Washing with warm water and an antibacterial shampoo is helpful once the area has been clipped. In some cases the lesions are so painful that heavy sedation or even an anaesthetic may be needed. Hygiene is imperative. A cotton sheet that can be removed and washed every day is helpful under rugs or saddles but it is far better to avoid any skin contacts at all.