What Is Rain Rot in Horses?

As a horse owner, when a light drizzle turns into a week-long rainstorm, you have more to do than patch the leaky ceiling. There are precautions you must take to ensure your horse—and their environment—stays safe, clean, and dry.

And these extra provisions aren’t just to keep mud off the horse’s hooves. Prolonged rainwater in a horse’s stall can cause something commonly known as rain rot.

Luckily, familiarizing yourself with this skin condition can ensure your horse stays as healthy as, well, a horse. Whether you’re in need of identifiers, preventative strategies, or treatment options, we’re confident our thorough guide will clear the clouds of rain rot for good.

Before we get into preventative care and treatment, let’s answer the basic question: what is rain rot in horses?

Rain rot (also known as rain scald) is an inflammatory skin infection that can occur in horses due to excessive rainfall, usually characterized by lesions, bumps, or scabs.

The scientific name for rain rot is dermatophilus, which manifests from a particularly moisture-loving bacteria called dermatophilus congolensis.¹

These dormant bacteria are actually harmless in dry conditions. They live on horses’ skin and bodies in dry conditions without doing much damage. However, when exposed to moisture, the bacteria can penetrate through multiple skin layers, leaving puss-filled bumps in their wake.

Over time, these bumps may lead to worsened symptoms such as dead skin, hair loss, and painful sores.

Excessive water can most famously lead to rain rot. However, more factors other than wet conditions can contribute to a severe case of this skin infection. Understanding these potential aggravators could help you discover how much your horse may be at risk.

Some relevant factors that can exacerbate rain rot include:²

• A damp environment – Too much water and dampness remain the common denominator for rain rot, but rainfall isn’t the only cause for wet conditions. Too much mud on the ground could stimulate the bacteria, as could high humidity or even a damp covering. Keep your horse safe by planning ahead of the wet weather to ensure they stay as warm and dry as possible.
• A weaker immune system – Rain rot affects horses with immune deficiencies at a higher rate. Therefore, if your horse gets sick regularly, they’re more likely to contract this skin condition. And though rain rot isn’t restricted to age, foals may catch it easier due to underdeveloped immunity.
• A lighter coat color – Horses with lighter coats tend to develop rain rot at a higher rate than those with darker coats.³ Some believe this is likely due to their more sensitive, unpigmented skin.
• Existing skin irritation – When a horse’s skin already has impairments, such as horse dermatitis, water can aggravate it more quickly, resulting in a rapid rain rot outbreak. Horses with existing bug bites, cracked skin, or dryness may be more susceptible to this condition.

If your horse is subject to any of these factors, you should stay on a sharp lookout and correct as many risks as possible.

If you’re unsure where to start, practice routine grooming procedures and stay on top of your veterinarian schedule. This can help improve overall skin health and immune system function.

Rain rot can materialize quickly, so identifying common symptoms before they worsen can help your horse make a speedy recovery.

After a bout of rain, make sure to inspect your horse for any of the following:

• Patchy lesions
• Mats of hair
• Raised bumps on the skin
• Scaly or crusty skin
• Dryness
• Scabs
• Bald patches

Though most of these symptoms seem mildly inconvenient, they can worsen over time. Some scabs, for example, may quickly turn from a puss-filled bump to a hardened one. They’re often more painful to remove and may leave a raw wound.

If your horse develops these symptoms after wet weather, you can likely diagnose them with rain rot relatively accurately. However, how do you know for sure whether your horse has it?

Some parasitic diseases can share rain rot symptoms. Ringworm, for example, can often include dry, flaky skin, hair loss, or scabby areas.⁴ While you can always call your veterinarian for skin scraping, you can also employ a few tactics to decipher the cause of your horse’s condition.

Consider the following practices when inspecting your four-legged friend:

• Check your horse’s back first – Rain rot typically materializes on your horse’s back, as that’s where rainfall naturally falls. However, bumps or scabs on your horse’s rump, face, or legs could also arise from rain rot. It is important to note, however, that if your horse is excessively scratching their legs, it also could be the cause of mud fever in horses.
• Feel for bumps under the fur – Though rain rot often presents itself visually, it can often hide beneath a thick coat. If you suspect your horse has this condition, feel free to use your hands to search for bumps under their fur. This method could help identify the infection early enough to prevent hair loss.
• Look for signs of skin pain – Many skin infections cause itchiness and rashes. Rain rot, however, feels more painful. When inspecting any abnormalities, pay attention to your horse’s behavior. If they twitch or whine at your touch, that could signal their physical pain and discomfort.

If you’re still unsure about the condition after careful inspection, you can always follow up with a trusted veterinarian for a proper diagnosis. It’s better to get an expert opinion than to wait for symptoms to worsen.

If your horse has rain rot, you can breathe easier knowing it’s highly treatable. The infection may take a while to clear up entirely, but with a bit of attentive care, your horse will feel gallop-giddy in no time.

Do you want to know how to treat rain rot on horses? Say good riddance to rain scald by practicing these treatment guidelines:⁵

• Clean the scabs – In order to fix this infection, you’ll need to rid your horse of harmful bacteria. A cleanser can efficiently clean bacteria from your horse’s coat as well as soften scabs adequately enough for safe removal. Lather their scabs in shampoo and let them sit for about 10 minutes before removing loose scabs. Once your horse is scab-free, you could introduce an extra topical anti-microbial to expedite the healing process.
• Brush the horse carefully – You can also help lessen the side effects and spread of symptoms by practicing gentle currying. Removing excess dirt, debris, and hair from the affected area helps keep the infected area from further irritation.
• Consider antibiotics – If the condition doesn’t improve within two weeks, you should consult a veterinarian about the possibility of antibiotic injections. If your horse requires a skin biopsy, your doctor can diagnose the issue and provide a thought-out schedule and therapy plan to get your horse back on track.

Whether your horse requires a trip to the doctor or a little extra grooming time, you can banish symptoms of rain rot and look forward to lovely weather ahead.

However, it’s crucial to note that horses can get rain scald more than once. So even after your horse’s health is restored, make sure to take the appropriate preventative measures to decrease the risk of future infection.

As with most ailments, preventative action proves the best way to combat infection. Unfortunately, you cannot control the weather. But you can act with extra caution to keep your horses from experiencing this infection.

Some of the best ways to prevent rain rot include:²

• Practicing regular grooming and bathing to cut down on existing irritants
• Avoiding wet, damp areas and opting for roofed shelter whenever possible
• Lowering exposure to mud
• Cleaning packed mud from hooves
• Eliminating excessive insects with increased sanitation, traps, or insecticides
• Waterproofing your horse with zinc or castor oil

Even in the dry season, you should stay on top of your horse’s health. Try Vetericyn’s Equine Shampoo for quality cleansing and conditioning for a glossy, hearty coat. Or you could opt for a medicated shampoo, which aims to eliminate harmful irritants, soothe damaged skin, and deliver essential nutrients for an immune system boost.

Rain rot occurs naturally, but it is also highly contagious. Slow the spread of dermatophilosis by separating infected horses from other horses in your stable.

Rain rot doesn’t just infect other horses. It can also spread to humans through exposed contact.

Take extra care to wear protective gloves when inspecting your horse for scabs. In addition, any scabs that you manage to remove should be disposed of swiftly and safely. Before heading inside for the night, thoroughly wash your hands with antibacterial soap.

When your horse starts feeling under the weather, it can be hard to banish the storm clouds—the metaphorical ones, and the ones that can lead to infections like rain rot.

Luckily, when you equip yourself with knowledge and quality pet care products, you can let the sun shine through—and your horse can swap out their rain rot for a healthy trot.

Swap out your rainy day for fairer weather with Vetericyn.

At Vetericyn, we believe in providing quality care for every pet. Whether your pet requires special shampoo, wound care treatment, or dietary supplements, we’re confident that our innovative technology can help your pet achieve new heights.