Ringworm in horses is treated with a combination of topical antifungal rinses applied to the whole body twice weekly, thorough cleaning of tack and equipment, and isolation of affected animals. Most cases resolve with topical treatment alone over three to six weeks, though stubborn infections sometimes require an oral antifungal prescribed by a veterinarian.
What Causes Ringworm in Horses
Despite the name, ringworm has nothing to do with worms. It’s a fungal skin infection, technically called dermatophytosis, caused by fungi that feed on keratin in the skin, hair, and hooves. The two most common species in horses are Trichophyton equinum and Trichophyton mentagrophytes, though several others can be responsible. The specific fungus involved sometimes influences where lesions appear: infections from Microsporum equinum, for example, tend to show up in the saddle, flank, and girth areas (places where tack creates pressure and friction), while Trichophyton verrucosum more often affects the limbs and rump.
Horses pick up the fungus through direct contact with an infected animal or by sharing contaminated equipment like brushes, clippers, halters, blankets, and saddle pads. The spores are hardy and can survive for months on barn surfaces, fences, and stall walls, which is why ringworm spreads so easily in barns and at shows.
Recognizing the Signs
The classic sign is circular patches of hair loss, sometimes with a raised, crusty edge. The skin underneath may look scaly, red, or inflamed. Some horses are itchy, others aren’t bothered at all. Lesions most commonly appear in the girth and saddle regions first, then spread to the face, neck, limbs, or back. In more widespread infections, the hair loss can give the horse a “moth-eaten” appearance rather than neat circles. You may also see raised, spongy areas of inflammation called kerions, particularly on the legs.
Ringworm can look similar to rain rot, insect bite reactions, or other skin conditions, so getting a definitive diagnosis matters. A veterinarian can confirm the infection through fungal culture (which takes about 14 days for a final result) or PCR testing (results in one to three days). PCR is highly sensitive and essentially rules out ringworm if the test comes back negative, but neither test alone can distinguish between a horse that’s truly infected and one simply carrying spores on its coat. Your vet will combine test results with a visual exam to make the call.
Topical Treatment: The First Line
Topical antifungal rinses are the core of ringworm treatment in horses. The standard approach is a whole-body, leave-on rinse applied twice per week. Three options are considered most effective:
- Lime sulfur dip diluted 1:16 with water
- Enilconazole (sold as Imaverol) diluted 1:50 with warm water
- Miconazole/chlorhexidine shampoo at a 2%/2% concentration
These rinses are left on the coat to dry rather than rinsed off. That contact time is what kills the fungus. On days between rinses, you can use a spray-on antifungal for additional coverage. Effective spray options include enilconazole (which stays stable for about seven days once mixed), or a chlorhexidine combined with either ketoconazole or miconazole.
For lesions near the eyes, where rinses and sprays could cause irritation, miconazole vaginal cream (1 to 2%) applied once daily is a safe alternative. It sounds odd, but it’s simply a convenient miconazole formulation that’s gentle enough for sensitive areas.
When using enilconazole specifically, the labeled protocol for horses calls for four treatments at three-day intervals, washing the lesions and surrounding skin each time. Your vet may extend this schedule if the infection is widespread or slow to clear.
When Oral Medication Is Needed
Most ringworm cases respond to topical treatment alone, but severe or resistant infections sometimes call for a systemic antifungal. Griseofulvin is the only FDA-approved oral antifungal for veterinary use and has proven effective against equine ringworm. For horses, it’s typically given by mouth daily for three to six weeks, sometimes longer if improvement is slow.
Griseofulvin does carry risks. It can cause liver damage, so horses with any existing liver problems should not take it. It’s also teratogenic, meaning it causes birth defects, and should never be given to pregnant mares. Your vet will weigh these risks against the severity of the infection before prescribing it.
Cleaning Tack and the Environment
Treatment on the horse will fail if you don’t address the spores lurking in the environment. Fungal spores can survive for months on grooming tools, blankets, stall walls, and fencing. A thorough decontamination plan includes several steps.
Start by scrubbing all surfaces with a strong detergent to remove organic material, since disinfectants don’t penetrate grime well. Follow that with a bleach solution at a 1:3 dilution (one part bleach to three parts water) for barn surfaces, stall walls, and fencing. Grooming equipment, feed buckets, and water pails should be cleaned with bleach solution as well. Leather tack should be cleaned, disinfected, then properly oiled afterward to prevent damage from the bleach.
Do not share brushes, clippers, halters, blankets, or saddle pads between the infected horse and other animals. If sharing is unavoidable in any situation, disinfect every item between uses. Wash all fabric items (saddle pads, leg wraps, blankets) in hot water with bleach when possible.
Isolation and Preventing Spread
An infected horse should be separated from other animals as soon as you notice lesions. Ringworm spreads readily through both direct contact and shared equipment, and a single infected horse in a busy barn can trigger an outbreak quickly. Keep the horse in a designated stall or paddock, with its own set of grooming tools and tack, until the infection has fully resolved.
You should also know that equine ringworm is zoonotic, meaning it can spread to people. The same fungi that infect horses cause the itchy, circular rashes you’d recognize as ringworm on human skin. Wear gloves when treating or grooming an infected horse. Wash your hands thoroughly with soap and running water after any contact with the horse, its equipment, or its stall. Keep hand sanitizer near the stall for yourself and anyone else who handles the horse. Children under five should be supervised during handwashing, and it’s best to limit their contact with an infected animal altogether.
What to Expect During Recovery
With consistent topical treatment and environmental cleaning, you should start to see improvement within two to three weeks. New hair growth in the bald patches is the clearest sign of recovery. Complete regrowth typically takes four to eight weeks depending on the extent of the infection and the time of year (hair grows more slowly in winter).
Don’t stop treatment early just because the patches look better. The fungus can still be active in the skin even after hair starts to regrow, and cutting treatment short is a common reason for relapse. Follow your vet’s recommended treatment duration, and consider getting a follow-up fungal culture to confirm the infection has truly cleared before reintroducing shared equipment or ending isolation.
Horses that recover from ringworm do develop some degree of immunity to the specific fungus that caused the infection, but they can still be infected by different fungal species. Continuing good hygiene practices, keeping shared equipment clean, and watching for early signs of hair loss will help you catch any reinfection before it spreads.