6 Horse Coat Fungus Treatments That Old-Timers Swear By

There’s nothing quite like that sinking feeling when you’re running a curry comb over your horse and your hand stops on a patch of crusty, scabby, or hairless skin. Fungal and bacterial skin infections are a persistent nuisance for any horse owner, thriving in the damp, muddy conditions that are a reality for most of us. Before you reach for expensive prescriptions, it’s worth knowing the tried-and-true remedies that have been passed down in barns for generations.

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Identifying Common Types of Equine Skin Fungus

Before you can treat it, you have to know what you’re looking at. Most skin crud falls into a few common categories, even if we use a dozen different barn names for them. Don’t get too hung up on the exact scientific name; focus on the visual clues.

Ringworm is the classic one. Despite its name, it’s a fungus, not a worm, and often presents as small, circular patches of hair loss with crusty, scaly skin. It’s highly contagious, spreading easily through shared brushes or tack.

Rain rot, or rain scald, isn’t technically a fungus but a bacterial infection (Dermatophilus congolensis) that acts like one. It creates matted tufts of hair with a scab at the base; when you peel one off, the underside often looks like a little paintbrush tip. You’ll typically find it along the horse’s topline—the back and rump—where rain pools.

Then there’s girth itch or saddle rot, which is often a form of ringworm or a similar fungal infection thriving in the warm, sweaty areas under tack. It looks like scaly, irritated skin, sometimes with hair loss. The key is recognizing that most of these issues thrive in moisture and are best tackled by making the skin an inhospitable place for them to grow.

The Acidic Power of an Apple Cider Vinegar Rinse

Fungus hates acid. This simple principle is why apple cider vinegar (ACV) has been a staple in the barn for decades. Creating an acidic environment on the skin’s surface makes it difficult for fungal spores to survive and multiply.

For a simple and effective rinse, mix raw, unfiltered apple cider vinegar 50/50 with water in a spray bottle. The "mother" in the unfiltered vinegar contains beneficial bacteria and enzymes that add to its effectiveness. After grooming, lightly spray the affected areas and let it air dry. You don’t need to soak the horse; a light misting is enough.

This is a great first line of defense for mild cases or as a preventative after a sweaty ride. The main trade-off is the smell, which is potent but fades as it dries. Be cautious applying it to raw or broken skin, as the acid will sting.

Using Listerine as an Antiseptic Skin Tonic

That classic, amber-colored bottle of original Listerine has more uses than just mouthwash. Its potent blend of antiseptic ingredients—thymol, eucalyptol, menthol, and alcohol—makes it a surprisingly effective topical treatment for skin funk. These ingredients work together to kill both fungus and bacteria on the surface.

A common approach is to dilute it 50/50 with water or, even better, witch hazel, which is a gentler astringent. Put it in a spray bottle for easy application. It’s particularly good for tackling that greasy, scaly buildup on cannon bones, often called "cannon crud," or for early signs of girth itch.

The biggest downside is that the alcohol content can be very drying to the skin if used too frequently or undiluted. Never use it on open wounds or very sensitive skin, as it will burn. But for localized, unbroken patches of crud, it’s a cheap and readily available tool that works fast.

Applying a Diluted Tea Tree Oil Solution

Tea tree oil is a powerhouse natural antiseptic, known for its potent antifungal and antibacterial properties. A little goes a very long way, and this is one remedy where more is definitely not better. Pure tea tree oil is far too strong and can cause severe skin irritation.

The key is proper dilution. Add about 15-20 drops of high-quality tea tree oil to a standard-sized spray bottle filled with water. Shaking it well before each use is crucial, as oil and water don’t stay mixed. For better blending, you can add an ounce of witch hazel to the bottle to act as an emulsifier.

This solution is excellent for spot-treating isolated areas like a single ringworm lesion. It’s less practical for widespread rain rot. As with any essential oil, it’s wise to do a small patch test on your horse first, as a small percentage of horses can have a skin sensitivity to it.

Medicated Cleansing with a Povidone-Iodine Scrub

When you need something stronger than a home remedy, a povidone-iodine scrub is the next step up and a fixture in any well-stocked vet kit. Products like Betadine Scrub are broad-spectrum antimicrobials, meaning they kill fungi, bacteria, and other microscopic troublemakers without prejudice.

The method is what makes it effective. First, gently wet the affected area with warm water. Apply the scrub and work it into a lather, making sure to get it down to the skin level. The most important step is to let it sit for a full 5 to 10 minutes before rinsing. This contact time is what allows the iodine to do its work.

After the time is up, rinse thoroughly until the water runs clear, as any residue can be irritating. Iodine is very effective but also very drying, so it’s not something for daily use. It can also temporarily stain white or grey coats a yellowish-orange, but that’s a small price to pay for clearing up a stubborn infection.

Harnessing Sulfur to Treat Persistent Rain Rot

For stubborn, crusty cases of rain rot, you sometimes have to bring out the big guns. Sulfur is an age-old remedy for all sorts of skin ailments because it has keratolytic properties, meaning it helps break down and shed the outer layer of dead, scabby skin where the infection is hiding.

Many old-timers make a concoction of "flowers of sulfur" (a fine sulfur powder available at some feed stores or online) mixed into a carrier like mineral oil, baby oil, or even bacon grease to form a paste. A popular commercial product, MTG (Mane-Tail-Groom), is a sulfur-in-oil preparation that accomplishes the same thing.

You apply the mixture directly to the rain rot scabs, let it sit to soften them, and then gently groom the loosened scabs away. The goal is to get the treatment onto the fresh skin underneath. The tradeoffs are significant: it is greasy, messy, and has a very distinct, powerful smell. But for a persistent case that won’t clear up, it’s often the one thing that finally works.

The Simple Effectiveness of Sunshine and Dry Air

This isn’t a product you can buy, but it’s arguably the most powerful treatment of all. Fungi and bacteria thrive in dark, damp, and oxygen-poor environments. The best way to fight them is to deny them the conditions they need to survive.

Sunlight is a natural disinfectant. The ultraviolet rays help kill off surface pathogens, and the warmth helps dry the coat completely. Good air circulation is equally important. A horse that is constantly blanketed or standing in a stuffy, damp stall is a prime candidate for skin problems.

Whenever possible, maximize turnout time in a dry, sunny paddock. If you must blanket, ensure the horse is completely dry beforehand and use breathable blankets. Curing a skin infection is just as much about good management as it is about applying a topical treatment.

Preventing Fungal Recurrence in Your Herd

Once you’ve won the battle against a skin fungus, the war isn’t over. The real goal is to prevent it from coming back. This comes down to a few key areas of horsekeeping hygiene.

First, stop the spread. Fungal spores are incredibly resilient and spread easily.

• Do not share grooming tools. Assign a set of brushes to each horse.
• Do not share saddle pads, girths, or blankets.
• If you have an active infection, wash your hands and disinfect your tools after handling the affected horse. A simple soak in a diluted bleach or Virkon S solution works well.

Second, manage the environment. A clean, dry living space is your best defense. This means regularly mucking stalls, ensuring good drainage in paddocks and sacrifice areas, and cleaning water troughs. A strong immune system, supported by good nutrition and low stress, also makes a horse far more resilient to opportunistic skin infections.

Ultimately, tackling horse coat fungus is a two-pronged attack of direct treatment and smart prevention. These old-timer remedies provide a fantastic, cost-effective toolbox for handling flare-ups. By combining them with a commitment to a clean environment and good herd hygiene, you can keep your horse’s skin healthy and save yourself a lot of time, money, and worry.