What is rain rot in horses, and how can you prevent it? Owning a horse in a wet or humid climate presents unique challenges, especially when it comes to maintaining healthy skin. Excess moisture creates ideal conditions for certain horse skin infections, one of the most common being rain rot, also known as rain scald. This bacterial skin condition can affect horses of all breeds and is typically triggered by prolonged exposure to damp, muddy, or unsanitary environments. To help you manage this issue effectively, we’ve broken down what rain rot is, what causes it, how to treat it, and most importantly, how to prevent it from recurring.

Facts About Rain Rot in Horses

• Horse rain rot is an opportunistic bacterial infection that affects the outer, protective layer of horses’ skin and produces crusty scabs.
• It is worse during the warm, humid months of the year, as that’s when the bacteria that causes rain rot, D. Congolensis, survives best.
• Rain rot can be largely prevented through good hygiene, regular once-overs, and providing adequate shelter from moisture to your horse.

What is Rain Rot on Horses?

Rain rot is the name for a bacterial infection of the epidermis which causes matted scabs containing hair clusters.

Also known as rain scald, can be found in horses of all ages, sexes, and breeds. However, younger horses, immunocompromised horses, horses with allergies that affect skin integrity, and horses with lighter coat colors are at a higher risk of developing rain rot.

Though these lesions are typically found on the horse’s topline, they can also be found on the rump, face, and legs.

What Causes Rain Rot on Horses?

Rain rot is a product of the bacteria Dermatophilus congolensis, a Gram-positive bacteria. Rain rot is usually observed most during warm, wet times of the year since spores in D. Congolensis require warm, moist climates to spread.

Horses who are blanketed during wet seasons tend to sweat more and offer an ideal environment (body warmth and wet surroundings) for D. Congolensis to grow. This is because tightly bound skin can’t easily secrete CO2. This sets up a scenario that allows the bacteria to germinate and penetrate into the dermis before spreading further. Over time, this causes an acute inflammatory response which produces the characteristic scabs of rain rot.

However, it should be noted that rain rot can only be established through a preexisting break in the skin. That’s why the two most common means of transmission are rubbing against equipment that’s contaminated by another horse and being bitten by infected insects.

Rain rot is a contagious skin condition that can spread between horses and even to humans. Transmission commonly occurs through direct contact, shared grooming equipment, or contaminated tack and blankets. To prevent the spread of rain rot, always wear gloves when handling affected horses, wash your hands thoroughly after treatment, and disinfect all brushes, combs, and tools used on the infected animal. Maintaining good hygiene and equipment care is essential for managing and preventing rain rot outbreaks.

Symptoms of Rain Rot on Horses

It begins presenting with small, pinpoint lesions that can easily be missed particularly if your horse has a long (winter) coat. Eventually these lesions coalesce into tufts of “paintbrush” shaped hair that are raised from the skin. If left untreated, these tufts of missing hair give rise to keratinized, wart-like scabs or crusts. In advanced cases a thick, yellow-green pus can be seen beneath the scabs.

In particularly severe cases, these lesions and scabs can become quite large and affect multiple layers of skin. If the infection progresses to this point, it can negatively impact your horse’s use for multiple months while the infection clears. If the infection is allowed to affect the lower limbs, similar scabby lesions will be found on the pastern and fetlock

The visibility of rain rot makes it relatively easy for equine veterinarians to diagnose. Not only are the lesions heavily visible, but the skin around them is also slightly painful and warm to the touch. This makes it easy for veterinarians to simply run their hands around the affected site and see how the horse reacts. If they flinch from discomfort and there are noticeable lesions, the veterinarian will likely make a presumptive diagnosis.

How to Treat Rain Rot on Horses

Proper treatment of rain rot is dictated by the severity of the infection. If your horse has a mild case of rain rot, they will likely heal with just a bit of extra attention.

For mild cases, simply bathing your horse with anti-microbial shampoo such as Banixx Medicated Shampoo or EquiShield CK Shampoo can be very effective at removing the scabs and eliminating the D. Congolensis bacteria. For more severe cases EquiShield CK HC Shampoo offers anti-inflammatory support, so this would be good for more severe cases or horses who are very sensitive. The antimicrobial shampoo for rain rot should contain some amount of chlorhexidine, povidone-iodine, or benzoyl peroxide. These are three of the most effective antimicrobial compounds available in commercial-grade anti-bacterial topicals.

Also, remember that contact time is very important for allowing antimicrobial solutions to work. You should leave any medicated shampoo soak for at least ten minutes on the affected areas before rinsing it off. Once rinsed off, the skin should be allowed to dry completely before applying any topical solution. Treatment of choice at this point is a potent yet gentle antimicrobial solution such as Banixx Horse & Pet Care spray that has no burn upon application and no foreign scent to alarm your horse. Because the spray is so easy to use, its easy to be consistent with application. Spray in the morning and evening until you start to see results, but note that new hair growth is extremely fine and tough to see with the naked eye in its early stages.

In addition to topical treatments, certain supplements and liniments can provide valuable support for horses prone to rain rot. While EquiShield® SC – Skin & Coat doesn’t directly treat rain rot or the bacteria that causes it, it helps strengthen the horse’s skin, coat, and immune system, making it especially beneficial for horses in hot, humid climates like Florida where skin infections are more common. When paired with medicated shampoos, sprays, and salves, this supplement can enhance skin resilience and reduce the likelihood of recurring outbreaks. Sore No-More® The Sauce is another excellent support option—a versatile liniment that not only offers pain relief for horses and dogs but also helps heal common skin and hoof conditions such as rain rot, thrush, sweet itch, and scratches. It works by drawing out heat, toxins, and fluid, aiding in faster recovery and overall skin health.

Rain rot treatment often involves a course of oral antibiotics prescribed by your veterinarian, typically administered for two to four weeks. Because rain rot is a bacterial skin infection, consistent treatment is essential for full recovery. While progress may be visible within the first week, it usually takes two to three weeks for the condition to fully clear. Early diagnosis, proper veterinary care, and patient management are key to successfully treating rain rot in horses.

What if My Horse Has a Severe Case of Rain Rot

If the affected horse has a particularly severe case of rain rot, your equine veterinarian may take a skin biopsy of the affected area to ensure it is afflicted by rain rot and not another infection. If rain rot is determined to be the culprit, the affected horse may require a regimen of strong, oral antibiotics to clear the infection.

In any case, horses with rain scald must be isolated away from other horses to prevent spreading the infection. Additionally, any scabs that are removed must be immediately thrown in the trash to prevent creating a source of reinfection. To that same end, be sure that the affected horse has his own grooming equipment and blankets. Disinfect and replace any contaminated equipment or grooming tools to help prevent spread. It’s not a bad idea to wash your horse’s blankets or sheets regularly also to keep infection rate low.

It’s important to remember that Dermatophilus congolensis, the bacteria that causes rain rot, can spread to humans. To protect yourself and others, always wear gloves when handling a horse with rain rot and wash your hands thoroughly afterward. Practicing proper hygiene and biosecurity helps prevent the transmission of this contagious skin infection from horses to humans.

What Happens if You Don’t Treat Rain Rot

Although it is an infection that tends to resolve on its own, horse owners should not delay in treating rain rot. If left untreated, the scabs can become sites where secondary infections breed; notably, staph infections and strep. Unfortunately, both of these infections are noticeably harder to treat, cost more to treat and many times more dangerous than rain rot.

How to Prevent Rain Rot on Horses

Thankfully, it is relatively easy to prevent rain rot in horses by taking a few simple steps.

First, and most important, practice good horse hygiene.  A solid, regular groom job on your horse is one of the best ways to avert rain scald. Of course, baths work well…but that just depends on your geographic area and farm or boarding circumstances. Good hygiene also means disinfecting and sterilizing all non-disposable equipment regularly. Remove manure and bedding from stables. Thoroughly wash all cloths, rags, or towels. And don’t forget those saddle pads!

You’ll also want to do a once-over of your horse’s entire body each day. You want to make sure there are no signs of cuts, swelling, injuries, or matted hair. If your horse has been exposed to lots of moisture recently, be sure to scrape off excess mud on their legs and barrel.

Along those same lines, try and limit your horse’s access to mud in their pasture as much as you can. Mud can get caked on your horse’s hair and skin which can open the door to infections later. Also, watch the populations of biting insects around your horses’ environment. If there’s been a population spike, consider using insect repellant such as Sore No-More classic Ricochet Horse Spray or UltraShieldEX Insecticide and Repellent to decrease your horses’ urges to scratch at bites. This will lessen the chance of your horse creating skin abrasions that provide D. Congolensis a safe place to live.

To help support your horse’s immune system and reduce the risk of recurring rain rot, consider adding a high-quality vitamin E supplement like Health-E®. As the most powerful antioxidant for skin health, vitamin E plays a key role in maintaining your horse’s natural defenses and promoting skin recovery. Health-E is specially formulated for horses, offering a potent, low-sugar, low-carb option ideal for horses prone to skin issues. Supporting immune function and skin integrity with Health-E may help your horse stay healthier year-round.

Give Your Horse Some Cover

It’s a good idea to make a plan that ensures your horse has adequate shelter in the field. That way they can easily access protection in the event of rain. Even things like trees or tall hedges can help reduce the incidence of overly wet skin and prevent infection.

Additionally, don’t over blanket your horse during the wet season. While blanketing your horse can provide protection from excess moisture, it can also be a double-edged sword. Over-blanketing your horse can actually trap moisture and lead to micro abrasions which are ripe for infection. If you plan on blanketing for the outside, waterproof your blanket. Follow the manufacturer’s specifications and let it dry after each use.

Final Tips for Managing Rain Rot in Horses

Rain rot in horses is a common but treatable equine skin condition that can cause discomfort and irritation if left unaddressed. By understanding the causes—such as excess moisture, poor grooming, or compromised skin—you can take effective steps to manage and prevent this type of horse skin infection. Regular grooming, keeping your horse dry, and using veterinarian-recommended topical treatments are key strategies for treating and preventing rain rot in horses. If symptoms persist or worsen, consult your vet to rule out other skin issues and ensure the right care plan is in place. With proper management, your horse can stay healthy, comfortable, and free from rain rot year-round.