Greasy Heel and Mud Fever in Horses
Greasy Heel and Mud Fever in Horses
Also called pastern dermatitis or scratches
Image by Natalie Alderwick
What is it?
Greasy heel (mud fever) is inflammation of the skin (dermatitis) on the lower legs of horses, especially under white socks, as unpigmented skin is more vulnerable. The skin can become red, swollen and cracked, with scabs, and may develop a greasy or sticky discharge. Left alone, it can cause lameness, so it's worth acting early.
What causes it?
The main culprit is Dermatophilus congolensis, an organism found everywhere in moist environments. It's the same one behind rain scald in horses and lumpy wool in sheep. Once it damages the skin, other bacteria and yeasts can move in.
In my experience as a vet, it usually develops when three things line up:
- Moisture — poor drainage, constant rain, humidity, dew or mud keeping the lower legs wet.
- Hygiene — dirty or muddy conditions mean more organisms around.
- Lowered skin immunity — even a slight drop can be enough.
Because the organism lives in stables and paddocks, you can never get rid of it completely. Expect it to come back whenever conditions suit it, and manage for that.
Managing greasy heel
Ask your vet to check your horse, especially if there's lameness, heat, a lot of swelling or the skin isn't improving. They may prescribe treatment. Day-to-day management usually involves:
1. Keep the legs dry and clean
Move the horse to dry ground where you can, and dry the legs thoroughly after washing or turnout. Clipping the hair on the lower legs helps the skin dry and makes cleaning easier.
2. Soften and remove scabs
Scabs can harbour the organism. Soften them with an oil or cream, then gently lift them off. Don't tear them away while still stuck to the skin.
3. Wash with an antiseptic
A povidone-iodine wash, or a dilute Condy's crystals (potassium permanganate) solution of about 50 mg per litre (roughly 1/10 teaspoon of crystals in 1 litre of water), can be used to clean the area. Condy's will stain brown. Always dry the area completely afterwards.
4. Protect the skin
Once clean and dry, a zinc-based ointment helps soften the skin and repel water. For maintenance between washes, many owners use my homemade yeast spray. Don't use it on raw or broken skin, as it stings.
5. Support from the inside
A good diet and general health support skin immunity. Many horse owners include turmeric in their horse's daily feed. See how to feed turmeric to horses.
Image by Natalie Alderwick
Remember: greasy heel often clears up with good management, but it can return within days if the legs stay wet. Prevention, through dry footing, clean legs and regular checks, is the long-term answer.
This page is general information and isn't a substitute for advice from your vet.
By Dr Doug English BVSc