Common Horse Skin Problems: Rain Rot, Scratches, Sarcoids, Proud Flesh and More

By Gayle Woods Editors Updated 7 min read

A horse's skin takes a beating: sun, rain, mud, flies, tack rubs and the occasional fence. Most skin problems are minor and respond to simple care, but a few need a vet, and a few spread to other horses or even to people. Regular grooming is the best way to catch them early, because you'll feel a scab or bump before you can see it.

Quick guide to common skin problems

Problem What it looks like Where Contagious?
Rain rot Crusty scabs that pull off with tufts of hair Back, rump, neck Yes, by shared gear
Scratches Scabby, red, sometimes oozing skin Back of the pasterns Sometimes
Ringworm Round patches of hair loss, scaly skin Girth, face, neck Yes, including to people
Sweet itch Rubbed, broken skin, hair loss Mane, tail, belly No
Hives Raised, round bumps that appear quickly Anywhere No
Sarcoids Warty, flat, or fleshy growths Face, ears, belly, groin Not easily
Proud flesh Pink, lumpy tissue bulging out of a wound Lower legs No
Melanomas Dark, firm lumps Under the tail, around the anus, head No

Rain rot

Rain rot, also called rain scald, is a bacterial skin infection caused by Dermatophilus congolensis. The bacteria live dormant in the skin and become active when the skin stays wet for long periods, especially when it's also damaged by insect bites or rubbing.

Signs: raised, crusty scabs, often along the topline where rain runs off. When you pick them, the hair comes away in small tufts like paintbrush bristles, leaving pink or gray skin, sometimes with pus.

Treatment:

  • Keep the horse dry, with shelter or a waterproof sheet. A blanket over a wet horse can make it worse, so dry the horse first.
  • Wash with an antibacterial shampoo, such as one containing chlorhexidine or benzoyl peroxide. Let it sit for several minutes before rinsing. See our horse shampoo picks.
  • Gently remove loose scabs after softening them. Don't scrub off scabs that are firmly attached; that's painful.
  • Dry the horse thoroughly afterward.
  • Disinfect brushes, pads and blankets, and don't share them between horses.

Severe or widespread cases, or cases that don't improve in a week or two, may need antibiotics from your vet.

Scratches (pastern dermatitis)

Scratches, sometimes called mud fever, is inflammation of the skin on the back of the pasterns. It's not one disease but a reaction with many possible causes: bacteria, fungi, mites, sunburn on white legs, and irritation from constant mud and wet bedding. Horses with white legs and heavy feathering, such as drafts, are most prone.

Signs: scabs, redness, hair loss and sometimes oozing or cracked skin. Severe cases can make the leg swell and the horse lame.

Treatment:

  • Clip the hair carefully from the area so you can see and treat the skin.
  • Wash gently with an antiseptic shampoo, rinse, and dry thoroughly.
  • Remove scabs only once they've softened.
  • Apply an ointment your vet recommends.
  • Keep the legs dry and clean: dry footing, clean stalls, and limiting turnout in deep mud.

Call your vet if the leg is swollen, the horse is lame, or the skin doesn't improve within a couple of weeks. Feathered horses with chronic scratches may have mites, which need specific treatment.

Ringworm

Ringworm is a fungal infection, not a worm. It causes round, scaly patches of hair loss, often where tack touches: the girth area, face and neck. It spreads easily between horses on shared brushes, blankets and tack, and to people. Wear gloves when you handle it.

Your vet can confirm it with a skin scraping or culture and recommend an antifungal wash. Disinfect everything the horse touches. Ringworm often clears on its own in a few weeks to months, but treatment shortens that and stops the spread.

Sweet itch and insect allergies

Sweet itch is an allergy to the bites of tiny biting midges (Culicoides). Affected horses itch so intensely they rub the mane and tail raw, and sometimes the belly. It tends to come back every summer and get worse with age.

Management centers on keeping midges off: stalling at dusk and dawn, fans, fly sheets with belly flaps and neck covers, and repellents. See how to get rid of horse flies. Your vet can prescribe medications to control the itch during bad spells.

Hives

Hives are raised, round bumps that appear suddenly, often within minutes to hours, and may cover a large area. They're an allergic reaction to something: a new feed, a medication, a fly spray, a plant or an insect bite.

Most hives fade within a day or two. Remove whatever you think caused them. Call your vet if they don't go away, keep coming back, or come with swelling around the face, breathing trouble or other signs of illness.

Sarcoids

Sarcoids are the most common skin tumor in horses. They're thought to be caused by a bovine papillomavirus, possibly spread by flies. They rarely spread to internal organs, but they can grow, multiply and get in the way of tack.

Types: flat, scaly patches; warty growths; firm lumps under the skin; and fleshy, ulcerated masses. They often appear around the eyes, ears, mouth, belly, sheath and groin.

What to do: call your vet. Don't pick at a sarcoid, cut it, tie it off or put caustic products on it. Irritating a sarcoid can make it grow faster or spread. Treatment depends on type and location and may include prescription creams, freezing, surgical or laser removal, or injections. Sarcoids often come back after treatment, so follow-up matters.

Proud flesh

When a wound heals, it fills in with pink, bumpy tissue called granulation tissue. On a horse's lower legs, where skin is tight and there's little muscle, the body sometimes makes too much. This excess tissue, called proud flesh, bulges above the edges of the wound and stops the skin from growing over it.

Signs: pink, moist, lumpy tissue that sticks up out of a healing wound, usually below the knee or hock, and often bleeds easily.

Treatment: your vet may trim it back, which is surprisingly painless because the tissue has few nerves, and then use pressure bandages and prescription ointments to keep it in check. Avoid caustic powders unless your vet recommends one; they damage healthy tissue too.

Preventing proud flesh starts with good wound care: keep lower-leg wounds clean, bandaged and still. See horse vital signs and first aid.

Melanomas in gray horses

Most gray horses develop melanomas, dark, firm lumps of pigment cells, as they age, often by their late teens. They usually appear under the tail, around the anus, on the sheath and around the head. Many grow slowly and cause no trouble for years, but some grow large or spread. Have your vet check new or growing lumps.

Other things to watch for

  • Lice cause intense itching and a patchy, rubbed coat in winter. Horse lice don't live on people. Your vet can recommend a treatment.
  • Sunburn affects pink skin on white noses and legs. Use a fly mask with a nose flap or a sunscreen safe for horses.
  • Tack rubs at the girth, withers and face come from poor fit or dirty tack. See how to fit a saddle.

How to prevent skin problems

  • Groom often. A curry comb brings up dirt and lets you feel bumps and scabs. Compare our grooming brush picks.
  • Keep horses dry, with shelter, dry footing and well-fitting waterproof sheets.
  • Don't share brushes, saddle pads, girths and blankets between horses with skin issues.
  • Control flies and midges.
  • Clean tack regularly. See saddle and leather care.

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Frequently Asked Questions