Bald Patches, Scabs, or Itching on Your Horse? What to Check First

Last updated: September 5, 2026

By: Miles HenryFact Checked

If your horse has a skin condition—or you’re helping a friend with one—the first job is figuring out what you are looking at and what may be causing it. A bald patch, crusty scab, tail rubbing, or small lump may not seem serious at first. But those signs can come from very different problems—moisture, insects, parasites, infection, irritation, or an abnormal growth—and each calls for a different approach.

In this article, I share what I’ve learned over decades of working with horses, along with current veterinary guidance on recognizing common skin problems, managing them safely, and knowing when it is time to call the vet.

Rain Rot (Dermatophilosis)

Rain rot is a bacterial infection caused by Dermatophilus congolensis that thrives in warm, damp conditions. Prolonged exposure to moisture, whether from rain or sweat trapped under a blanket, creates the conditions the bacteria needs to take hold. It shows up as crusty scabs with matted, paintbrush-like tufts of hair, most often along the back, rump, and legs – places that stay wet the longest.

Management focuses on keeping the horse dry, gently loosening only the scabs that release easily during washing with an antiseptic shampoo, and getting veterinary guidance for anything severe or slow to improve. The organism can spread between horses through close contact or shared equipment, so don’t share brushes, blankets, or tack until the problem is under control. Wear gloves when practical and wash your hands after handling affected skin, especially if you have cuts or broken skin.

Ringworm

Despite the name, ringworm is a fungal infection, not a worm, caused by dermatophyte fungi. It typically shows up as circular, scaly, hairless patches that can spread quickly if left untreated. It’s genuinely contagious – to other horses and to people – spreading through shared grooming tools, tack, and bedding.

Sweet Itch

Sweet itch is an allergic reaction to the saliva of Culicoides midges, and it’s one of the most frustrating conditions for horse owners to manage. Affected horses develop severe itching along the mane, tail, and sometimes the belly and face, rubbing themselves raw against anything available. There’s no cure – only management, focused on reducing midge exposure: fly sheets, stabling during dawn and dusk when midges are most active, and insect repellents. Severe cases may need veterinary treatment with antihistamines or corticosteroids.

Other Skin Conditions to Know

Allergic and Contact Dermatitis

Allergic dermatitis causes itching and redness when a horse reacts to something in its environment, most commonly insect bites. Contact dermatitis is a direct reaction where a substance touches the skin, such as a plant, chemical, topical product, or residue on tack or blankets. The first step is removing the likely trigger when you can identify it. Chronic or recurring cases need veterinary help because treating each flare-up without identifying the cause is frustrating for both horse and owner.

Lice and Mites

Lice and mites both cause itching, rubbing, and hair thinning, but they are different parasites and do not always call for the same treatment. Lice may be visible when you part the hair; mites are usually too small to see and often need a veterinary skin scraping or examination to confirm. If a parasite problem is confirmed, ask your veterinarian which horses need treatment and how to clean shared equipment, blankets, and bedding to reduce reinfestation.

Sarcoids

Sarcoids are the most common skin tumors in horses. They are associated with bovine papillomavirus, although researchers are still working to understand exactly why some horses develop them. A sarcoid can look like a small wart, a hairless scaly patch, a firm lump, or a more aggressive ulcerated growth. Do not pick at, cut off, tie off, or apply home remedies to a suspicious lesion. A veterinarian should identify it and recommend treatment based on its type, size, and location, because sarcoids can recur and one treatment does not suit every case.

Scratches, Hives, and Photosensitization

A few other skin problems deserve a place on every horse owner’s radar. Scratches, also called pastern dermatitis, causes scabs, cracks, swelling, and soreness around the pasterns and heels. It has more than one possible cause, including prolonged moisture, bacteria, mites, and irritation, so treatment depends on what is driving it. Hives are raised welts that can appear suddenly after insect exposure, a new product, medication, feed change, or another trigger. Photosensitization can cause painful, crusting, peeling skin on white or lightly pigmented areas after sun exposure and may be linked to plants, medications, or liver disease.

Call your veterinarian promptly for widespread hives, facial swelling, trouble breathing, painful sunburn-like lesions, marked leg swelling, or pastern sores that are not improving. Those problems can look simple at first and become much harder to manage once the skin is badly inflamed or infected.

Grooming for Skin Health

Regular grooming keeps the coat cleaner, helps you notice moisture trapped under blankets or in feathering, and gives you the best chance to spot a small problem before it becomes a large one. During shedding season, grooming removes loose hair and helps you see the skin beneath it. In winter, pay extra attention to the legs and areas under blankets, where dampness and rubbing can go unnoticed.

A curry comb loosens dirt and stimulates circulation; a soft brush distributes natural oils and smooths the coat; a mane and tail comb detangles without breaking hair. The real value, though, is the inspection that happens along the way – running your hands over the horse and actually looking for scabs, bumps, bald spots, or anything that feels different than last time.

Nutrition and Skin Health

Diet plays a real role in coat and skin condition. Protein quality, omega-3 fatty acids, zinc, copper, and biotin all support skin repair and hair growth, and a horse on a diet that’s short on any of these can develop a dull, thin, or slow-growing coat. Exact amounts depend on the individual horse, their workload, and what the rest of the diet already provides – work with your vet or an equine nutritionist rather than adding supplements based on a generic number, since over-supplementing some minerals can cause its own problems. For the full breakdown, see horse coat nutrition for a shiny, healthy coat.

When to Call the Vet

Reach out to your veterinarian for persistent lesions or swelling, severe itching or hair loss you can’t explain, or any unusual growth or lump – especially anything that doesn’t resolve, keeps changing, or shows up alongside other signs like lethargy or weight loss. Ringworm, sarcoids, and severe allergic reactions all need a professional diagnosis rather than a guess from appearance alone. Acting early on any of these tends to mean a simpler, shorter path to resolving it.

Horse Skin Conditions: FAQs

A horse’s coat really is a mirror of its overall health. Regular grooming, good nutrition, and catching problems early go a lot further than any single treatment – and knowing which of these conditions you’re actually looking at makes all the difference in how fast it clears up.