Why Does My Horse Have Scabs, Hair Loss or Itchy Skin?

By Dr Duncan Houston

A patch of hair loss, a few crusty scabs, or an itchy horse rubbing on the stable door can look simple at first. The problem is that many horse skin diseases look almost identical, even when the causes are completely different.

Ringworm, bacterial folliculitis, rain scald, allergies, lice, mites, pastern dermatitis, contact irritation, and even some tumors can all cause hair loss, crusting, bumps, itching, or scaly skin. Treating them all the same way is where owners get into trouble.

The goal is not to guess from a photo or throw random creams at the skin. The goal is to understand the pattern, reduce spread, avoid making the lesion worse, and know when a vet needs to test the skin.

Quick Answer

Horse skin problems that cause scabs, hair loss, itching, or crusty patches are commonly caused by fungal infection such as ringworm, bacterial skin infection, allergies, lice, mites, insect bites, moisture-related dermatitis, or contact irritation. Because many equine skin diseases look similar, diagnosis often requires history, physical examination, skin scrapings, hair or scale examination, cultures, or biopsy. If lesions are spreading, painful, oozing, recurrent, affecting multiple horses, or not improving within a few days, a veterinary diagnosis is the safest next step. (Merck Veterinary Manual)

Why Horse Skin Problems Are So Easy To Misread

The skin has a limited number of ways to react.

Whether the trigger is fungus, bacteria, parasites, allergy, trauma, moisture, or irritation, the visible signs may still be:

• Hair loss

• Scabs

• Crusts

• Scaling

• Redness

• Itching

• Bumps

• Oozing

• Thickened skin

• Pain when touched

That is why a “round bald patch” does not automatically mean ringworm, and an itchy horse does not automatically mean sweet itch. Merck Veterinary Manual notes that many horse skin diseases have a similar appearance, and accurate diagnosis may require history, physical exam, microscopic examination, cultures, blood or urine tests, and sometimes biopsy. (Merck Veterinary Manual)

In practice, the most important clues are timing, location, itchiness, pain, seasonality, whether other horses are affected, and whether the skin is dry, wet, crusted, swollen, or infected.

Common Horse Skin Problems and What They Look Like

The pattern is the first clue, not the final answer.

Ringworm in Horses

Ringworm is not caused by a worm. It is a fungal infection of the skin and hair.

In horses, ringworm is commonly caused by dermatophyte fungi such as Trichophyton equinum and Trichophyton mentagrophytes. It can spread through direct contact, contaminated stalls, grooming tools, tack, broken hairs, and skin scale. Some ringworm fungi can also spread from horses to people. (MSD Veterinary Manual)

Typical signs include:

• Circular bald patches

• Scaling

• Broken hairs

• Crusts

• Mild redness

• Lesions around the saddle or girth area

• Spread to the neck, chest, flanks or head

Ringworm may clear on its own over time, but treatment can speed recovery and reduce spread. Diagnosis is usually by fungal culture or microscopic examination of hairs and skin scale. MSD Veterinary Manual also notes that treatment commonly relies on topical therapy, and infected horses should be isolated while tack and contaminated fabric items are cleaned thoroughly. (MSD Veterinary Manual)

The clinical trap is that bacterial folliculitis can look very similar to ringworm.

Bacterial Skin Infections and Staph Folliculitis

Bacterial skin infections in horses often involve the hair follicles. This is commonly called bacterial folliculitis or pyoderma.

Staphylococcus species are common causes. Lesions may form circular areas of hair loss that look like ringworm, which is why bacterial folliculitis is often under-diagnosed and ringworm can be over-diagnosed. (Stable Management)

Signs may include:

• Raised bumps under the coat

• Small pustules

• Crusts

• Circular bald areas

• Painful scabs

• Oozing lesions

• Hair that pulls out easily

• Lesions under tack, saddle pads, girths or rugs

Bacterial skin infections often develop after something damages the skin barrier, such as sweat, friction, tack rubs, clipping trauma, insect bites, allergies, moisture, or existing dermatitis.

Mild focal cases may respond to vet-directed topical treatment, but widespread, painful, recurrent, draining, or non-responsive cases may need cytology, culture, and antibiotic sensitivity testing.

This matters because resistant bacteria can occur. Methicillin-resistant Staphylococcus aureus, or MRSA, has been reported in horses and can cause wound infections, cellulitis, catheter-site infections, pneumonia, septic arthritis, and skin infections. It can also be zoonotic, meaning transmission between horses and people is possible. (Veterinary Extension)

Use gloves when handling suspicious infected skin, especially if there is pus, discharge, or a history of resistant infection.

Rain Scald and Moisture-Related Crusting

Rain scald, also called rain rot or dermatophilosis, is a bacterial skin disease often associated with prolonged wet conditions.

It can cause:

• Matted hair

• Crusts

• Wart-like lesions

• Tufts of hair lifting with scabs

• Soreness in some cases

• Widespread lesions over the back, rump, neck or limbs

MSD Veterinary Manual describes dermatophilosis as a bacterial skin infection that is more common in young, immunosuppressed, or chronically wet animals. Diagnosis may involve cytology or bacterial culture, and treatment includes topical or systemic antimicrobials along with husbandry changes to keep the animal dry. (MSD Veterinary Manual)

The key point is that drying the horse and changing the environment are part of the treatment. Medication alone may fail if the horse remains wet under rugs, in muddy turnout, or in damp bedding.

Allergies and Insect Bite Hypersensitivity

Allergies can cause itching, hives, hair loss, crusting, and secondary infection.

The most common allergic skin problem in many horses is insect bite hypersensitivity, often called sweet itch. Culicoides midges are a major trigger, but other biting insects can also contribute.

UC Davis describes clinical signs of insect bite hypersensitivity as itching, skin thickening, lesions, scaling, crusting, hives, and hair loss. Lesions are often found on the trunk, face, mane, tail, and ears, with the exact location depending on the biting pattern of the insects involved. (Center for Equine Health)

Allergy becomes more likely when signs are:

• Seasonal

• Worse in spring, summer or autumn

• Focused around the mane or tail

• Worse at dawn or dusk

• Associated with midges, flies or mosquitoes

• Recurring at the same time each year

Treatment for insect bite hypersensitivity relies mainly on reducing insect exposure with stabling during peak insect activity, rugs, fly masks, repellents, fans, manure removal, and standing water control. Corticosteroids may reduce clinical signs, but antihistamines have not been shown to be especially effective for insect bite hypersensitivity. Omega-3 fatty acids may help reduce skin inflammation. (Center for Equine Health)

The mistake is treating the skin while the horse is still being bitten every day.

Lice in Horses

Lice are a classic cause of winter and early spring itching.

Horses can be affected by chewing lice and blood-sucking lice. Lice infestations are more common in horses with long winter coats, feathering, poor condition, overcrowding, poor nutrition, or underlying illness. (MSD Veterinary Manual)

Signs include:

• Rubbing

• Biting at the skin

• Restlessness

• Hair loss

• Matted coat

• Rough or unthrifty appearance

• Visible lice or nits when the hair is parted

• Small wounds from sucking lice that may become infected

Diagnosis is often made by parting the hair and seeing lice or nits. Ordinary shampooing does not remove nits because they are glued to the hair shaft. Treatment usually involves appropriate insecticidal products, repeated treatment, and cleaning of equipment and areas contacted by affected horses. MSD notes that repeat treatment 14 to 21 days after the first application is needed to control infestations. (MSD Veterinary Manual)

Horse lice are species-adapted and are not normally attracted to humans, but they spread between horses, so contact animals and shared equipment matter. (Merck Veterinary Manual)

Severity Guide: How Worried Should You Be?

A small dry patch on a bright horse is usually less urgent than a painful, spreading, wet, swollen skin infection. The real concern is progression.

What Else Can Look Like Ringworm, Allergy or Lice?

A strong skin article needs this section because equine skin disease is rarely kind enough to read the textbook.

Important rule-outs include:

Mites
Especially around the lower legs in horses with feathers. Look for stamping, chewing, rubbing, pastern scabs, crusting and recurrent lower-leg irritation.

Pastern dermatitis
This is not one disease. It may involve moisture, bacteria, fungi, mites, allergies, sunlight sensitivity, contact irritation or chronic lower-leg disease.

Pinworms
Can cause tail rubbing, especially around the base of the tail and anus.

Contact irritation
New fly spray, medicated shampoo, detergents, bedding, rugs, boots, wraps, plants or topical products can irritate the skin.

Food reaction
Less common, but possible. Usually considered after more common causes have been ruled out.

Skin tumors
Sarcoids, squamous cell carcinoma and other growths may look like non-healing wounds, warts, ulcers or recurring scabs.

Autoimmune or immune-mediated disease
Less common, but important in chronic, severe, unusual or recurrent crusting.

Dermatophilosis
Rain scald can look like bacterial, fungal or allergic skin disease, especially in wet conditions.

If a skin problem is not behaving as expected, it should be rechecked. A lesion that does not respond to the “obvious” treatment may not be the obvious diagnosis.

When Is This an Emergency?

Most skin disease is not an immediate emergency, but some signs need urgent care.

Call a vet urgently if your horse has:

• Fever

• Depression or reduced appetite

• Severe pain

• Rapidly spreading swelling

• Lameness

• Hot, swollen limbs

• Pus or foul-smelling discharge

• Deep cracks or ulcers

• Bleeding or raw self-trauma

• Widespread hives with facial swelling

• Breathing difficulty

• Eye involvement

• Lesions on the penis, sheath, vulva or anus

• A wound hidden under scabs

• Multiple horses suddenly affected

• Suspected MRSA or resistant infection

• No improvement despite several days of sensible care

The biggest red flags are pain, swelling, systemic illness, rapid spread, and involvement of sensitive areas.

How Vets Diagnose Horse Skin Disease

A vet will usually start with the history.

Useful details include:

• When the problem started

• Whether it is spreading

• Whether it is itchy or painful

• Whether signs are seasonal

• Whether other horses are affected

• Recent changes in feed, bedding, rugs, tack, sprays, shampoos or turnout

• Whether the horse has been wet, sweating, clipped or rugged

• Previous treatments and whether they helped

• Whether the horse has long feathers or a winter coat

• Whether there are wounds, discharge or swelling

Tests may include:

• Skin scraping for mites

• Hair plucks

• Tape test

• Cytology for bacteria or yeast

• Fungal culture for ringworm

• Bacterial culture and sensitivity

• Wood’s lamp examination in selected fungal cases, although it is not reliable for all equine dermatophytes

• Biopsy for chronic, unusual or non-responsive lesions

Merck Veterinary Manual highlights that diagnostic testing may include microscopic analysis of skin scrapings and hair, skin swab cultures, blood and urine tests, and biopsies, and that more than one visit may be needed for an accurate diagnosis. (Merck Veterinary Manual)

That is not overcomplicating it. It is how you avoid treating a fungal infection with antibiotics, a bacterial infection with antifungal cream, or a mite problem with shampoo alone.

What Should You Do Right Now?

1. Stop sharing equipment

Until you know what the condition is, do not share:

• Brushes

• Rugs

• Saddle pads

• Girths

• Boots

• Towels

• Clippers

• Tack that touches affected skin

Ringworm, lice, mites, bacteria and other infectious causes can spread through direct contact or contaminated equipment.

2. Photograph and map the lesions

Take clear photos every few days.

Record:

• Location

• Size

• Itchiness

• Pain

• Discharge

• Spread

• Whether other horses are affected

• What changed recently

This helps your vet more than vague descriptions like “it looks worse.”

3. Avoid riding over affected skin

If lesions are under the saddle, girth, bridle, boots or rug, stop friction over that area.

Friction can turn a mild lesion into a painful infected one.

4. Keep the horse clean and dry

Do not leave sweat, mud, wet rugs, damp saddle pads or dirty wraps against the skin.

Dry management is especially important for rain scald, pastern dermatitis, bacterial infection and fungal overgrowth.

5. Do not apply steroids until infection is considered

Steroid creams can reduce inflammation, but they can also worsen some infections if used incorrectly.

This matters especially when ringworm, bacterial infection, mites or an infected wound are possible.

6. Do not over-wash

Washing can help in some cases, but repeated washing without proper drying can damage the skin barrier and make moisture-related problems worse.

Use medicated shampoos only as advised, with correct contact time and thorough rinsing.

7. Call your vet if it spreads or does not improve

If lesions are spreading, painful, oozing, recurrent, affecting multiple horses, or not improving within a few days, arrange a vet check.

Waiting weeks while rotating products usually delays the correct treatment.

Common Mistakes Owners Make

Assuming every round patch is ringworm
Bacterial folliculitis can also produce circular hair loss and crusting.

Using leftover antibiotics
Wrong drug, wrong dose or wrong duration can worsen resistance and fail to treat the real problem.

Using corticosteroids too early
Steroids can aggravate some infectious skin diseases when used without diagnosis.

Not isolating suspected ringworm
Ringworm can spread through horses, tack, grooming tools and the environment.

Only treating the worst horse
Lice, mites and ringworm may involve contact horses too.

Over-bathing and not drying
Wet skin is vulnerable skin. Drying is part of treatment.

Ignoring pain
Painful skin lesions are more concerning than mildly scaly patches.

Not cleaning gear
Dirty brushes, rugs, saddle pads and clippers can keep reintroducing the problem.

How To Prevent Horse Skin Problems

Prevention is about protecting the skin barrier and reducing spread.

Useful habits include:

• Groom regularly and check under the coat

• Inspect saddle, girth and rug areas after work

• Keep tack and saddle pads clean

• Dry sweaty horses before rugging

• Avoid leaving damp rugs or boots on

• Keep bedding clean and dry

• Manage mud and wet turnout areas

• Control flies and biting insects

• Check horses more carefully in winter coats

• Inspect feathered legs for mites and pastern dermatitis

• Do not share brushes or rugs during outbreaks

• Clean clippers between horses

• Quarantine new horses when appropriate

• Treat all in-contact animals when your vet recommends it

• Investigate recurring skin disease rather than repeating failed treatments

The best prevention is not glamorous. It is clean gear, dry skin, early detection and not letting small lesions become yard-wide problems.

Will My Horse Be Okay?

Most horse skin problems are manageable once the cause is identified.

Ringworm can spread quickly, but it is usually treatable. Lice are uncomfortable, but treatment is usually effective when repeated correctly and equipment is cleaned. Bacterial infections often respond well when the underlying trigger is removed and treatment is targeted. Allergic horses may need long-term management, especially if insect bite hypersensitivity is involved.

The cases that become frustrating are usually the ones treated by guesswork for too long.

If the horse is bright, comfortable, and the lesion is small and stable, you have time to organise a sensible plan. If the skin is spreading, painful, wet, infected, swollen, affecting multiple horses, or not improving, get a diagnosis before more time is lost.

FAQs

Is ringworm in horses contagious to people?

Yes, some equine ringworm fungi can spread from horses to people. Wear gloves when handling suspicious lesions, wash hands well, avoid sharing equipment, and ask your vet about diagnosis and control. (MSD Veterinary Manual)

How can I tell ringworm from bacterial folliculitis?

You often cannot tell reliably by appearance alone. Both can cause circular hair loss and crusting. Fungal culture, cytology, and sometimes bacterial culture are used to confirm the cause.

Can horses get lice from humans?

Horse lice are not normally attracted to humans. They are more important as a horse-to-horse problem, especially in long coats, winter coats, feathering, overcrowding or poor health. (Merck Veterinary Manual)

Should I use antifungal cream on every circular patch?

No. Circular patches may be fungal, bacterial, parasitic or inflammatory. Treating blindly can delay the correct diagnosis and may allow contagious conditions to spread.

When should I call a vet for horse skin disease?

Call a vet if lesions spread, last more than a few days, are painful, oozing, swollen, itchy, recurrent, involve multiple horses, or affect the eyes, genitals, lower limbs, or areas under tack.

Final Thoughts

Horse skin disease is rarely solved by guessing.

The same scab, bald patch or itchy area could be ringworm, bacterial folliculitis, rain scald, lice, mites, allergy, contact irritation, pastern dermatitis or something more serious. What matters is the pattern, the progression, the location, and whether the horse is painful, infected, itchy or spreading it to others.

The safest approach is simple: stop sharing equipment, photograph the lesions, reduce friction and moisture, avoid random creams, and get veterinary testing when the problem is spreading, painful, recurrent or unclear.

Good skin treatment starts with the right diagnosis. Everything else is just hoping the cream picked the right enemy.

If you are unsure whether your horse’s skin problem is ringworm, bacterial infection, allergy, lice, mites, rain scald or something more serious, ASK A VET™ can help you work through the signs and decide what to do next.