If your horse is diagnosed with “Scratches”, it does not mean he has fleas or is allergic to his food! It does mean he has a crusty skin reaction that has plagued horses and their owners since at least the early 1800s.
Scratches has many other colorfully descriptive names such as greasy heel, mud rash, mud fever, cracked heels and dew poisoning. Veterinarians recognize scratches as a pastern dermatitis affecting the heels and skin in the back of the pastern area just above the hoof. Most commonly, the hind legs are affected, especially when they have lots of hair, or feathers, or have white hair with unpigmented skin.
Pastern dermatitis has many causes but all result in the same red, crusty, erosive sores that are painful to the touch. As the sores deepen, the leg can become swollen and cause significant lameness. When the skin barrier is weakened by chronic exposure to moisture, dirt, and manure, even a small scratch can allow pathogens to enter the body. Careful diagnostics must be done to diagnose the cause because bacterial, fungal, or even parasitical infections result in the same painful crusts. Your veterinarian can take a detailed history, skin scrapings, and skin cultures to ultimately find the culprit.
Prevention is the best cure. Good management such as keeping your horse’s environment as clean and dry as possible, keeping the hair around the lower limb trimmed short and irritants like flies to a minimum will help. Connecticut had a very wet fall and cases of pastern dermatitis dramatically increased. The colder, drier environment of winter is welcome to help resolve these cases.
Most often a gentle cleansing with an antibiotic/antifungal shampoo in an effort to soften the crusts is helpful. Aggressive scrubbing and forceful removal of the crusts is never recommended. It’s painful for your horse and will make the sores worse. If your horse is lame and swelling is moving up the leg, you should call your veterinarian to discuss more specific treatment. It can take a while for pastern dermatitis to resolve even with the best of care. Be patient and know that you and your horse are not the first and won’t be the last to suffer through this pesky problem!