Grease Heel, Greasy Heel, Scratches or Mud Fever

Horse running in mud
Natalie Alexeeva (anakonda) / EyeEm / Getty Images

Grease heel is common in the spring and fall. It’s unsightly and while not immediately dangerous for a horse, can become serious. If caught early, persistent home treatment can be effective, but if left, grease heel can make your horse lame and lead to serious infection.

Other Names for Grease Heel

Grease heel is also called dermatitis verrucosa, seborrheic dermatitis, mud fever, scratches, dew poisoning or greasy heel.

There are many regional names for this condition.


Grease heel appears on lower legs as patches of scurf beneath hair. The hair itself will start to look  thinned, matted or staring. Under the scurf, the skin will be itchy, irritated,  red, cracked, and oozing a thick, mucous-like or ‘greasy’ fluid. If the grease heel is mild, it may only look dry and dandruffy. It may not be as obvious on horses with a lot of feathering on its lower legs. If left, the skin will become more inflamed and cracked. The lesions may become crusty as the fluid dries onto the affected areas.

Cracked skin in the lower legs can be difficult to heal since the area is always flexing as the horse walks. The pain from the inflamed skin can cause the horse to appear lame.

Left untreated the skin can become deeply cracked, and eventually, infected. Granulomas, a type of scar tissue and equine cellulitis, an inflammation of the deeper layers of skin, resulting in heat and swelling in the legs, can develop.


The same conditions that cause rain scald also cause grease heel: microbes that thrive in mud and wet. If pastures and paddocks are muddy, it may be hard to provide a place where the horse’s hoofs and legs aren’t wet. However, if the horse’s legs are constantly damp, the microbes that cause grease heel can thrive.

Grease heel may be more prevalent in the spring when pastures are muddy from snow melt and rain, and again in the fall when the weather is wet. Damp stall conditions, especially if ammonia from urine builds up, can cause and exacerbate grease heel. Horses with white legs and pink skin are more likely to be bothered by grease heels than darker skinned horses. Sunburn, sweat and poorly fitting and cleaned leg boots can make your horse more susceptible to grease heel.


Grease heel may appear to disappear or be slightly better during dry weather. But grease heel can flare up quickly when the weather turns damp again. Keep your horse in clean, dry conditions. Keep its stall clean and don’t allow dampness and ammonia from urine to build up. Keep paddocks and pastures free of manure build-up, and improve drainage if mud is a problem. Avoid turning horses out in dewy pastures while the grease heel is at its worst.  Frequent grooming can remove dirt and dander that give the microbes a home. Wash your horse’s legs down after exercise to remove sweat and make sure they are dried thoroughly.

Treating Grease Heel

Mild grease heel can be treated by brushing away any dirt and dead hair, washing with an antiseptic or anti-fungal soap, and working a topical like an antiseptic cream or zinc oxide paste through the hair onto the skin.

Some owners claim that creams designed to treat yeast infections are effective. Zinc oxide creams or lotions are also effective. Look for diaper creams such as Ihle’s Paste or Desitin with a high quantity of zinc oxide.  Keep the area clean and dry and continue treating until the condition is gone. If the grease heel is severe, you may want to wrap the area to prevent dirt sticking to the cream,but keep in mind wraps or bandages may hold in dampness. Keep the horse in a clean dry area to prevent recurrence. Make sure any leg boots or bandages are cleaned and dried thoroughly between uses.

Any brushes or equipment used on a horse with grease heel should be sterilized before use on another horse. It may be easier to keep a separate set of brushes for each horse being treated to prevent cross-contamination.

Wash your hands after treating a horse with grease heal, to avoid spreading this and other skin conditions to others.

If the grease heel covers a large area, has become badly cracked or there is any evidence of swelling or infection, call your veterinarian. Granulomas caused by grease heel can be removed by a veterinarian.