Hair Loss In Horses: Causes, Signs & When To Call A Vet

Last updated: September 4, 2026

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I bought some yearlings with bald spots in their coats. Hair loss like this isn’t unusual, but before you start treating it, you need to know what you’re dealing with.

Why is my horse losing hair in patches? The most common causes are:

Ringworm — often circular or irregular bald patches with dry, scaly, or crusty skin; it is fungal, not a worm, and can spread to other horses and people
Rain rot or rain scald — matted tufts of hair and crusts that lift away, often leaving tender skin underneath; it is associated with prolonged wet conditions
Sweet itch — severe rubbing along the mane, tail head, belly, or face caused by sensitivity to biting midges
Mites or lice — itching, rubbing, broken hair, and crusty or thickened skin; mites often affect lower legs, while lice are commonly found around the mane, neck, flanks, and tail head
Rubbing or friction — hair loss where a halter, blanket, saddle pad, breast collar, feeder, or fence rubs repeatedly
PPID (equine Cushing’s disease) — a long, curly, uneven, or poorly shedding coat in an older horse, often with other changes such as topline loss or increased drinking
Diet or systemic illness — more likely to cause a dull, thin, slow-growing, or generally poor coat than a few clean bald circles

I’ve dealt with hair loss in my own horses, and in this article I’ll share what I’ve learned from experience along with what veterinary research says about the different causes.

The First 5 Things I Check When a Horse Loses Hair

Before treating a bald patch, I slow down and look at the whole horse and the situation around it. These checks do not replace a veterinary diagnosis, but they help prevent treating every patch of missing hair as the same problem.

Is the horse itchy? Rubbing, tail switching, stomping, or a horse trying to scratch on every post points me toward insects, lice, mites, or another itchy skin problem.
What does the skin look like? I note whether it is dry and flaky, wet under matted hair, crusty, thickened, red, painful, or smooth and normal.
Is hair falling out or being rubbed off? Broken hair at a halter, blanket, saddle, feeder, or fence line may be friction rather than infection.
Is another horse affected? When more than one horse develops lesions or itching, I think harder about contagious disease, parasites, shared equipment, turnout, and management changes.
Is this an older horse that is not shedding normally? A long, curly, delayed-shedding coat along with topline loss, increased drinking, or repeated infections is a reason to ask the veterinarian about PPID testing.

Miles’s Take: Start With the Pattern When I see patchy hair loss, I do not start by buying a medicated shampoo or a supplement. I first look at where the patch is, whether the horse is rubbing, what the skin looks like, and whether another horse has the same problem. Those details help me describe the issue clearly to my veterinarian and avoid wasting time on the wrong treatment.

Ringworm and rain rot are two conditions owners commonly confuse. This quick comparison can help you notice the difference, but a veterinarian may need to examine the horse or test skin and hair to confirm the cause.

Feature	Ringworm	Rain Rot
Skin and hair	Often dry, scaly, or crusty patches with broken or missing hair	Matted tufts or crusts that lift off, often with tender skin beneath
Typical pattern	Round or irregular patches that may spread or multiply	Raised crusts or paintbrush-like tufts, often over the back and hindquarters
Spread and hygiene	Can spread among horses and to people through contact or shared equipment	Can spread through close contact or contaminated equipment; wet conditions are an important trigger
Cause	Dermatophyte fungal infection	Dermatophilus congolensis infection

Normal Shedding vs. Alopecia

Horses normally shed twice a year. In spring, they lose the heavier winter coat; in fall, they make the transition to a winter coat. During those changes, plenty of hair may come out when you groom, and the coat can look rough or uneven while new hair comes through. That is normal.

Alopecia is different. It means abnormal hair loss, especially bald patches with visible skin, a pattern concentrated in certain areas, sudden rubbing, broken hair, or skin changes such as scale, crusts, redness, thickening, or moisture. A horse can have a normal shed and a skin problem at the same time, so the pattern matters more than the amount of hair in your curry comb.

Patch of hair missing from a horses coat

What I Look For When I See a Bald Patch

I don’t have photos of each condition to show you here, so here’s the mental checklist I actually run through instead – a word picture rather than a photo gallery:

Dry, scaly patches: ringworm moves higher on my list.
Matted tufts or paintbrush-like crusts: I think about rain rot, especially after prolonged wet weather.
Heavy rubbing at the mane or tail: sweet itch becomes more likely.
Hair missing exactly where tack or a halter contacts: I check for friction before reaching for a treatment.
An older horse with a long, curly, or delayed-shedding coat: PPID deserves a veterinary conversation.
Several horses affected: I start thinking about contagious disease, parasites, shared equipment, or a management change.

Ringworm

Despite its name, ringworm is a fungal infection, not a worm. It is a common cause of patchy hair loss in horses and often produces circular or irregular areas of broken hair, bald skin, scale, or crusting. Lesions can start small, spread outward, and show up in more than one place. The face, neck, girth area, saddle area, and other places touched by tack or shared grooming tools are common locations.

Miles’s Take: Do Not Assume Every Bald Patch Is Rain Rot One mistake I have seen is treating every patch of missing hair as rain rot. I pay more attention to the skin and the pattern than to the fact that hair is gone. Dry scale and expanding patches make me think differently than matted tufts after days of wet weather. But when ringworm is possible, I treat it as a biosecurity issue and get veterinary advice rather than guessing from appearance alone.

Ringworm Can Spread to People and Other Horses Ringworm can spread through direct contact and through shared grooming tools, tack, blankets, and other equipment. Wear gloves when practical, wash hands after handling the horse, and keep that horse’s brushes and equipment separate until you know what you are dealing with. If anyone develops a suspicious circular, itchy rash after contact with the horse, they should contact a healthcare professional.

Veterinarians may confirm ringworm by examining hairs and skin or by fungal culture. Treatment varies with the extent of the infection and your veterinarian’s recommendations, but it usually includes an antifungal topical product and thorough cleaning of the horse’s environment and equipment. Spores can remain on brushes, tack, blankets, and surfaces, so treating the horse while ignoring the equipment invites another round of the same problem. Good grooming hygiene and separate equipment for affected horses are sensible prevention steps.

Rain Rot or Rain Scald

Rain rot, also called rain scald or dermatophilosis, is associated with Dermatophilus congolensis. It often appears as matted, paintbrush-like tufts of hair and crusts that lift away from the skin. The back, hindquarters, topline, and other areas that stay wet are common places to find it. Under a loosened crust, the skin may be tender, moist, or irritated.

Long periods of wetting, humidity, a damp coat, and small breaks in the skin all make rain rot more likely. It can spread through close contact and contaminated equipment, so do not share brushes, blankets, tack, or towels without cleaning them. Keeping the horse dry is a major part of management, but it is not the only concern when lesions are widespread, painful, or recurring.

Management usually includes getting the horse dry, using a veterinarian-recommended topical treatment, and gently loosening only crusts that release easily during washing. Avoid aggressively picking adhered scabs or scrubbing raw skin. Severe, painful, widespread, or non-improving cases deserve veterinary attention; some horses need prescription treatment. Whether you can ride depends on the severity and where the lesions are located, especially if tack would sit on sore skin. Read more about riding a horse with rain rot and the factors to consider.

Miles’s Take: Rain Rot in Louisiana In Louisiana, rain rot is a near-constant management challenge during wet stretches. The lesson we have learned is that treating the spots is only half the job. A horse that gets soaked and stays wet for hours will keep having trouble. Dry shelter, dry blankets, and frequent checks after rainy weather do more to prevent serious cases than waiting until the coat is already coming out in clumps.

Sweet Itch

Sweet itch is an allergic reaction to the bites of Culicoides midges. The defining feature is usually intense itching, not simply hair loss. Horses rub along the mane crest, tail head, belly, ears, or face until hair breaks off and skin becomes thickened, scaly, or wounded. Chronic cases can leave the mane and tail thin and the skin toughened from repeated rubbing.

There is no simple cure, so management focuses on reducing midge exposure and controlling the horse’s itch. That can include bringing the horse in around dawn and dusk, using well-fitted fly protection with neck and belly coverage, reducing standing-water exposure where practical, and discussing medical options with your veterinarian when the horse is miserable or damaging its skin.

Miles’s Take: Insect Pressure Can Escalate Fast In the South, a little seasonal rubbing can turn into a horse rubbing itself raw in a short time when insect pressure is high. I do not wait for a horse to tear out half its mane before improving fly protection. Once the skin is broken, you are managing the itch and trying to prevent a secondary skin infection too.

Mites and Mange

Several mites can affect horses. Chorioptic mites are commonly associated with itching, stomping, crusts, thickened skin, and hair loss around the fetlocks and lower legs. Horses with heavy feathering can be especially difficult to assess because the warm, damp hair around the lower legs creates a favorable environment for skin problems.

Other mite infestations can cause more widespread itching, scaling, scabbing, and secondary infection. Mites are often difficult to see without magnification, and a veterinarian may use a skin scraping or other examination to help identify the problem. That matters because mites, lice, fungal disease, bacterial skin disease, and allergy can overlap in appearance but do not call for the same treatment. See this guide to mites, lice, and other external parasites in horses for more detail.

Lice

Lice are often noticed in winter or when horses are in closer contact, wearing blankets, or carrying a longer coat. They can cause enough itching and rubbing to leave broken hair or thin patches around the mane base, neck, flanks, shoulders, and tail head. If you part the hair in good light, you may see small, slow-moving lice or pale nits attached to hair shafts.

Horse lice are generally host-specific, so they are not considered a human or dog infestation. Still, all horses that have had close contact may need attention, and blankets, brushes, tack, and bedding need to be cleaned to reduce reinfestation. Ask your veterinarian which product and repeat-treatment schedule fit the type of lice, the horse’s age, and the rest of your herd. Get veterinary help if you are not certain the problem is lice, the horse is severely itchy, or the skin is damaged or infected.

Rubbing From Tack, Halters, Blankets, or Fences

Not every bald patch is caused by an infection or parasite. A tight halter, poorly fitting blanket, rubbing saddle pad, breast collar, fly mask, or repeated rubbing on a feeder or fence can break hair or wear it off in a predictable spot. Look for hair loss directly under the equipment or at the exact rubbing point, especially when the skin is smooth and there is no spreading scale, crusting, or obvious itch.

Correct the fit and remove the source of friction before assuming a medicated product is needed. But a patch that is raised, sore, ulcerated, bleeding, thickened, or unchanged after the rubbing source is fixed should be examined by your veterinarian. A persistent hairless patch is not something I would keep calling a simple halter rub month after month.

PPID, Often Called Equine Cushing’s Disease

Pituitary pars intermedia dysfunction, or PPID, is a hormonal disorder most often seen in older horses. A long, curly, delayed-shedding, or uneven coat is one of the best-known signs. A horse that still carries a shaggy winter coat into warm weather deserves more attention than a stronger curry comb. Other possible signs include loss of topline muscle, abnormal fat distribution, increased drinking and urination, repeated infections, and increased laminitis risk.

PPID requires a veterinary examination and endocrine testing. Resting endogenous ACTH testing is commonly used, and your veterinarian may recommend a TRH-response test or other testing depending on the horse’s signs and the time of year. Treatment decisions, including the use of pergolide, should be made with your veterinarian. Early recognition matters because controlling PPID can improve comfort and helps manage related risks, including laminitis in horses.

Miles’s Take: Older Horses Often Show It in Their Coat First Older horses often tell us something is changing through their coat before they look obviously sick. When an older horse does not shed normally or starts carrying a long, uneven coat along with muscle loss or extra drinking, I do not write it off as age. That is a good conversation to have with the veterinarian.

Diet, Systemic Illness, and Other Less-Obvious Causes

Diet problems and some systemic illnesses can show up in the coat, but they more often cause a dull, thin, brittle, slow-growing, or generally poor coat than a handful of clean bald circles. Protein quality, essential amino acids, trace minerals such as zinc and copper, and overall calorie intake all affect hair and skin. A forage-based diet that looks adequate on paper can still have gaps, particularly when hay quality changes or a horse has higher needs.

I would not add a handful of supplements just because a horse’s coat looks poor. Start with good forage, body condition, a realistic look at the full diet, and – when the problem persists – a forage analysis and a conversation with your veterinarian or an equine nutritionist. Over-supplementing is not harmless; selenium, for example, can become a problem when horses receive too much. For more background, see how nutrition supports a healthy horse coat.

Persistent focal lesions, lumps, ulcers, pain, bleeding, or patches that do not improve after obvious rubbing is corrected also need a veterinary examination. Not every hairless spot is a common skin infection.

Quick Guide to Patchy Hair Loss in Horses

Possible Cause	What You May Notice	Common Location	What to Do First	When to Call the Vet
Ringworm	Scaly or crusty patches with broken or missing hair; may spread	Face, neck, saddle area, girth area	Separate equipment, improve hygiene, and ask for veterinary guidance	Promptly if lesions are widespread, uncertain, spreading, or not improving
Rain rot	Matted hair tufts and crusts, often with tender skin beneath	Topline, back, hindquarters	Keep the horse dry; clean shared equipment; use veterinarian-recommended care	If painful, widespread, feverish, recurrent, or not improving
Sweet itch	Marked rubbing, broken hair, thickened skin, or open wounds	Mane crest, tail head, belly, face	Reduce midge exposure and improve fly protection	If the horse is miserable, breaking skin, or needs itch control
Mites	Crusty or thickened skin, itching, stamping, rubbing	Often lower legs and fetlocks	Do not assume; arrange veterinary evaluation for a correct diagnosis	When mites are suspected or lesions are spreading
Lice	Rubbing, broken hair, visible insects or nits when hair is parted	Mane, neck, shoulders, flanks, tail head	Check herd mates and clean blankets, brushes, tack, and bedding	If diagnosis is uncertain, the infestation is heavy, or skin is damaged
Friction or rubbing	Hair loss exactly where equipment or a surface contacts the horse	Halter, blanket, saddle, breast collar, feeder, fence	Correct fit and remove the rubbing source	If the area is painful, raised, ulcerated, bleeding, or does not improve
PPID	Long, curly, delayed-shedding, or uneven coat; may have topline loss	Usually whole-body coat change	Schedule a veterinary examination and discuss endocrine testing	As soon as the coat change is noticed in an older horse, especially with other signs
Diet or systemic illness	Dull, thin, brittle, slow-growing, or generally poor coat	Usually diffuse rather than isolated circles	Review forage, full diet, body condition, and recent changes	If the coat problem persists, weight changes occur, or the horse seems unwell

This guide helps you notice patterns; it cannot diagnose the cause of hair loss. For veterinary background, see the Merck Veterinary Manual guide to hair loss in horses, the Merck Veterinary Manual guide to dermatophilosis (rain rot), and Cornell’s PPID testing guidance.

When to Call the Vet About Hair Loss

I would call the veterinarian sooner rather than later if the hair loss is spreading quickly, more than one horse is affected, the horse is intensely itchy, the skin is raw or painful, or you suspect ringworm, mites, or PPID. I would also call if the horse has fever, lethargy, weight loss, increased thirst or urination, lameness, or other signs that suggest this is more than a surface skin problem.

It is also worth making the call when a patch does not respond after you fix an obvious problem, such as a rubbing halter or wet blanket. A veterinarian can use skin scrapings, fungal culture, hair and skin examination, or blood work when needed. That is often faster and cheaper than cycling through shampoos, sprays, and supplements while the condition gets worse.

FAQs About Horses Losing Hair in Patches

What causes alopecia or patchy hair loss in horses?

Alopecia means abnormal hair loss. Common causes in horses include ringworm, rain rot, sweet itch, mites, lice, rubbing from tack or blankets, and PPID in older horses. Diet problems or systemic illness can also affect coat quality, though they are more likely to cause a generally poor or thin coat than a few neat bald patches. The pattern and skin changes can help narrow the possibilities, but a veterinary examination may be needed for a diagnosis.

Is ringworm in horses dangerous to humans?

Ringworm is a fungal infection that can spread from horses to people. It may cause a circular, itchy skin rash in humans. Use gloves when practical, wash hands after handling an affected horse, and do not share grooming tools, tack, blankets, or other equipment. Anyone who develops a suspicious rash after contact with the horse should contact a healthcare professional.

What does rain rot look like on a horse?

Rain rot often looks like matted, paintbrush-like tufts of hair or crusts that lift away from the skin. It commonly appears over the back, topline, and hindquarters after wet weather. The skin beneath a loosened crust may be tender or moist. Because other conditions can look similar, have a veterinarian examine widespread, painful, recurring, or uncertain lesions.

Can PPID or Cushing’s disease cause coat problems in horses?

Yes. PPID, often called equine Cushing’s disease, can cause a long, curly, uneven, or delayed-shedding coat, especially in older horses. Other signs may include topline muscle loss, increased drinking and urination, recurrent infections, and laminitis risk. A veterinarian can assess the horse and recommend appropriate endocrine testing, often including endogenous ACTH testing.

When should I call the vet if my horse is losing hair?

Call your veterinarian if the hair loss spreads quickly, the horse is very itchy, the skin is raw, painful, swollen, or infected, another horse is affected, or you cannot identify the cause. Also call for a poorly shedding or abnormal coat in an older horse, or for hair loss accompanied by weight loss, lethargy, increased drinking, lameness, or other illness signs.

Miles Henry

About Miles Henry

Racehorse Owner & Author | 30+ Years in Thoroughbred Racing

Miles Henry (legal name: William Bradley) is a professional horseman based in Folsom, Louisiana. He holds Louisiana Racing License #67012 and has spent over three decades managing Thoroughbreds at premier tracks including Fair Grounds, Delta Downs, and Evangeline Downs.
Expertise & Hands-On Experience: Beyond the track, Miles has decades of experience in specialized equine care, covering everything from hoof health and nutrition to training protocols for Quarter Horses, Friesians, and Paints. Every guide on Horse Racing Sense is rooted in this “boots-on-the-ground” perspective.
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Why Is My Horse Losing Hair? What I Check Before Treating It

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