How to Identify and Treat Ringworm in Horses

31 March 2026

Ringworm in horses is one of the most contagious — and most misunderstood — skin conditions in the equine world. It is not a worm at all but a fungal infection of the outer skin layers, caused primarily by Trichophyton equinum and to a lesser extent Microsporum equinum, Microsporum gypseum and Trichophyton mentagrophytes. Despite being almost universally self-limiting in healthy adult horses, ringworm can sweep through a yard in a fortnight, jump to humans, dogs and cats, and leave fungal spores lurking in tack rooms for over a year. This guide tells you how to spot it early, treat it properly, and stop it spreading — using UK-licensed products and protocols backed by the Royal Veterinary College, British Horse Society biosecurity guidance and the MSD Veterinary Manual.

What Is Ringworm in Horses?

Ringworm — clinical name dermatophytosis — is a superficial fungal infection of the hair shaft and the keratin layer of the skin. The fungi responsible are called dermatophytes, and in horses around 80% of cases are caused by Trichophyton equinum. The "ringworm" name comes from the characteristic circular patches of hair loss that often (but not always) develop, and from the raised, slightly inflamed edge that can resemble a worm crawling under the skin. There is no actual worm involved.

Ringworm spreads either by direct horse-to-horse contact, or — more commonly on yards — by spores contaminating tack, rugs, grooming kit, fence rails, water buckets and stable walls. Dermatophyte spores can survive in the environment for 12 to 18 months and are remarkably resistant to ordinary cleaning agents. That spore survival is the single most important fact to grasp: if you only treat the horse and not the yard, the infection will keep coming back.

How Do Horses Catch Ringworm?

Direct contact with an infected horse — particularly common during shows, clinics, sales and new arrivals to a yard.
Shared tack — saddle pads, girths, bridles and exercise sheets carry spores between horses. Saddle pads are the single highest-risk item on a yard.
Shared grooming kit — brushes, curry combs, mane combs, sponges, clippers.
Shared rugs — fly rugs and turnout rugs in particular.
Fence rails, mounting blocks, stable doors — anywhere horses scratch.
Cattle and other livestock — bovine ringworm (Trichophyton verrucosum) crosses to horses on shared grazing or shared yards.
Rodents — wild mice and rats can introduce Trichophyton species into feed rooms.

The incubation period is six days to six weeks. That long window means a horse can arrive at a new yard apparently healthy and only develop lesions a fortnight later — by which time tack has been shared, paddocks have been used, and the spores are everywhere.

Who Is Most at Risk?

Young horses — foals, yearlings and youngstock under three years are by far the highest-risk group because their immune system has not yet developed acquired resistance.
Geriatric horses — over 18s, especially those with PPID/Cushing's disease, have suppressed immunity.
Horses on long-term corticosteroids — for example chronic equine asthma.
Horses in dense housing — show stables, sales yards, racing yards, livery yards with high turnover.
Wet, dark winter conditions — the warm, humid environment under a turnout rug is ideal for fungal growth.
Horses with broken or abraded skin — girth galls, scratches and tack rubs let the fungus colonise more easily.

What Does Ringworm Look Like on a Horse?

The textbook image is a perfectly circular bald patch with a raised, scaly edge. In practice the lesions vary enormously, which is why ringworm is so often missed in the early stages.

Early-stage lesions (days 6–14)

Small tufts of hair standing up against the lie of the coat — usually 1–2 cm in diameter.
The tufts feel slightly raised when you run a hand over them.
No itchiness, no obvious pain.
Commonly first appears in the girth area, behind the elbow, under the saddle, on the side of the face, around the eyes, or on the lower legs.

Established lesions (weeks 2–6)

The tufts fall out, leaving roughly circular bald patches 1–3 cm across.
The skin underneath looks silvery, scaly or slightly crusty — sometimes pinkish where it is freshly exposed.
A raised inflamed ring may surround the lesion.
Multiple lesions can merge into larger irregular patches.
Some weeping or oozing in severe cases — usually a sign of secondary bacterial infection.

Where ringworm typically appears

Saddle and girth area — most common in adult horses.
Head, around eyes, muzzle and ears — common in foals.
Neck under the headcollar.
Inside the thighs and along the brisket.
Lower legs — particularly if the horse has scratched itself.

How to Diagnose Ringworm in Horses

Most experienced equine vets can diagnose ringworm visually with reasonable confidence based on appearance, location and the herd context. Laboratory confirmation is reserved for unusual cases or where outbreaks need to be reported (for example competition yards).

Wood's lamp examination — a UV light. Useful for some Microsporum species which fluoresce apple-green, but Trichophyton equinum (the most common cause in horses) does not fluoresce, so a negative result does NOT rule out ringworm.
Hair plucks for direct microscopy — hairs plucked from the edge of an active lesion can be examined under a microscope for fungal hyphae and spores. Quick result, moderate sensitivity.
Fungal culture — hair and skin scraping plated on dermatophyte test medium (DTM). The gold standard but slow (10–21 days).
PCR — increasingly available through commercial UK laboratories such as VetGen, Easy-DNA and the Royal Veterinary College's Equine Skin Service. Fast and highly sensitive.

Ringworm needs to be distinguished from several look-alikes, particularly sweet itch, mud fever, rain scald, sarcoids, demodectic mange, and pressure sores from poorly fitting tack. If a circular bald patch persists for more than 8 weeks, gets steadily larger, or refuses topical antifungal therapy, you are probably dealing with something else — call your vet.

How to Treat Ringworm in Horses

Ringworm is self-limiting in immunocompetent adult horses — it will resolve in roughly 4 to 12 weeks without any treatment as the horse mounts an immune response. However, you should never simply ignore it because:

An untreated horse will shed infectious spores continuously for that entire period.
Spores contaminate the yard environment for 12+ months afterwards.
Other horses, the owner and any visiting dogs and children are at risk of catching it.
The horse cannot be ridden in the saddle/girth area while lesions are open — affecting work and competition plans.

Step 1 — Isolate

Move the affected horse to a single stable, ideally at the end of the yard. Allocate dedicated grooming kit, rugs, tack, water buckets and feed bins to that horse only. Mark them with coloured tape so nobody mistakes them for general yard kit. The handler should change clothes and wash hands after each visit. Where possible, deal with the infected horse last in the daily routine.

Step 2 — Clip the affected areas (carefully)

Clipping the hair from around lesions exposes the skin to topical therapy and removes spore-loaded hairs. Use dedicated clippers — they must be disinfected afterwards with an antifungal disinfectant. Dispose of clipped hair by burning or sealing in a plastic bag for landfill — do NOT compost it. Do not clip the entire horse; you do not need to, and the bare skin then needs additional protection.

Step 3 — Topical antifungal wash

The topical treatment most commonly used by UK equine vets is enilconazole — sold as Imaverol (Elanco). The dilution is 1 part Imaverol to 50 parts warm water, applied as a wash across the affected areas and the immediate skin around them. Apply four times at three-to-four-day intervals (so days 1, 4, 8 and 12), wearing gloves throughout. Do not rinse off — let it air dry.

Alternative UK-licensed and commonly used options:

Equine Skin Wash containing miconazole and chlorhexidine — twice weekly for 3–4 weeks.
Natamycin spray (e.g. Mycophyt) — applied to lesions every 3–4 days.
Lime sulphur dip (less common in the UK, more common in South Africa) — diluted 1:16 weekly.
Povidone-iodine scrub (10%) — useful in mild cases, applied every 2–3 days.

Athlete's-foot creams (clotrimazole, terbinafine) work on small, localised lesions but are impractical for body-wide treatment.

Step 4 — Treat secondary bacterial infection if present

If lesions are weeping, crusty or smell sour they have probably picked up a secondary bacterial infection (usually Staphylococcus). Your vet may prescribe a topical antibacterial scrub or, in heavy cases, a short course of systemic antibiotics. Do not self-prescribe — antibiotic stewardship matters and most ringworm does not need them.

Step 5 — Systemic antifungals (rarely)

Oral antifungals like griseofulvin (no longer licensed for horses in the UK due to mutagenicity concerns) and itraconazole are reserved for severe, generalised or refractory cases — for example immunocompromised horses or extensive lesions covering large areas. Always under veterinary supervision.

Step 6 — Vaccination (Europe only, limited UK use)

A live attenuated vaccine — Insol Dermatophyton (Boehringer Ingelheim) — is available in continental Europe and can be imported into the UK on a Special Treatment Certificate. It is occasionally used in studs and high-throughput sales yards as a preventative. It is not first-line therapy for an outbreak.

Yard Biosecurity: Stopping Ringworm Spreading

This is the half of treatment owners most often skip and immediately regret. The horse will recover faster than the yard environment will.

Disinfect everything the infected horse has touched

Use an antifungal-rated disinfectant — household bleach (sodium hypochlorite) diluted 1:10 with water is effective on hard surfaces, as are Virkon S (Antec), F10SC (Health and Hygiene) and Stalosan F powder.
Wash all rugs, saddle pads, exercise sheets and bandages at 60°C minimum with a hot tumble dry afterwards. Below 60°C, spores survive.
Saddles and bridles — wipe down with diluted F10SC or a 1:10 bleach solution applied with a damp cloth (not soaking — leather damage). Let dry, then re-oil.
Clippers, hoof picks, brushes and curry combs — soak overnight in F10SC or Virkon, rinse, dry thoroughly. Replace foam or fabric items rather than trying to disinfect them.
Stable walls — power-wash, dry, and apply Stalosan F powder or whitewash with antifungal additive.
Wooden fencing — paint with lime wash where possible.

Protect the humans

Equine ringworm is zoonotic — it readily transfers to humans, particularly children, who often catch it on the arms, neck and face. Adults pick it up on the forearms from grooming, and on the inner thigh from riding. Wear long sleeves and gloves when handling an infected horse, shower and change clothes immediately afterwards, and watch for circular itchy red patches on your own skin over the following four weeks. Human ringworm responds rapidly to over-the-counter clotrimazole cream — but if it appears on a child's scalp (tinea capitis), see a GP immediately because oral antifungal treatment is usually required.

Protect dogs and cats

Yard dogs and barn cats can pick up the same fungal species — particularly Microsporum. If your yard dog develops a circular bald patch over the next two months, ringworm is the prime suspect. Keep dogs out of the infected stable.

Ringworm Prevention

For routine yard management

Quarantine all new horses for at least 14 days before mixing them with the resident herd. This is the single most effective control measure.
Never share saddle pads, girths or grooming kit between horses. Label everything by horse.
Wipe down communal areas — mounting blocks, tie-up rings, wash bays — weekly with F10SC or diluted bleach.
Avoid shared rugs at shows and clinics. Bring your own.
Treat any cattle on shared land for ringworm — bovine ringworm is the most common cross-species source for outbreaks in mixed yards.
Limit rodent populations in feed stores.

For competition and travel

Avoid borrowing tack at venues.
Disinfect rugs and saddle pads between events.
Inspect new arrivals — particularly young horses returning from stud or sales — daily during the 6-week incubation window.

How Long Does Ringworm in Horses Last?

Untreated: 4 to 12 weeks for lesions to clear; spores remain on the horse for up to 6 months.
With proper topical treatment (Imaverol or similar): 2 to 4 weeks for lesions to clear.
Environmental spores in the yard: 12 to 18 months without aggressive decontamination.
Hair regrowth: 6 to 12 weeks after lesions resolve.

Once a horse has recovered, it usually develops partial immunity — re-infection is possible but tends to be milder and more localised.

Frequently Asked Questions About Ringworm in Horses

Can humans catch ringworm from a horse?

Yes. Equine ringworm is zoonotic and transfers readily to humans through direct contact or contaminated tack and grooming kit. Most human cases respond well to over-the-counter clotrimazole cream. Scalp involvement in children usually needs oral antifungal medication prescribed by a GP.

How quickly does ringworm spread between horses?

The incubation period is 6 days to 6 weeks, but new lesions can appear on yardmates within 1–2 weeks of exposure if biosecurity is poor. Sharing saddle pads, girths and grooming kit is the fastest route.

What is the best treatment for ringworm in horses?

In the UK the standard treatment is enilconazole wash (Imaverol) at 1:50 dilution, applied four times at 3–4 day intervals, combined with strict isolation and full environmental decontamination. Mild localised lesions can be managed with miconazole, natamycin or povidone-iodine.

Can I ride a horse with ringworm?

You should avoid ridden work over active lesions in the saddle, girth or bridle areas — both because tack pressure delays healing and because tack will become contaminated. Light in-hand work over unaffected areas is acceptable but increases environmental contamination risk. Most yards request that ringworm-positive horses do not attend shows or clinics until lesions have fully resolved.

Does ringworm go away on its own?

In healthy adult horses, yes — typically over 4 to 12 weeks. However, the horse remains infectious to other horses, humans and pets for that entire period, and spores contaminate the yard environment for up to 18 months afterwards. Active treatment is strongly recommended.

How do I disinfect tack after ringworm?

Wash all fabric items at 60°C with a hot tumble dry. Wipe leather tack with a damp cloth dipped in diluted F10SC or 1:10 household bleach, let dry, then re-oil. Soak grooming kit and clippers overnight in F10SC or Virkon S. Replace foam saddle pad inserts rather than attempting to disinfect them.

Final Word

Ringworm in horses is one of those conditions where doing the work properly the first time saves you months of repeat outbreaks. The horse itself rarely suffers — itchy, ugly patches that vanish within a few weeks. The real cost is the yard biosecurity work, the disinfecting, the isolation and the lost weeks of competition and training. Catch it early, isolate hard, treat with the right antifungal, and scrub the environment as if you mean it. Do that once and the outbreak ends. Skip the environmental work and you will be doing this again next winter, with a different horse.