­­­­How to Treat Rain Rot on Horses

Last Updated on January 24, 2022

According to popular belief, the best time to set our horses into the pastures is when the weather becomes warm and sunny or when there is a little dewy outside, Right? Unfortunately, those are the conditions when rain rot in horses most commonly appears.

In the northern parts of the world, during the spring, summer and winter season closest to the equator, as part of your horse’s daily care, be sure to keep an eye for this disease and take the necessary steps towards curing and preventing it from affecting your horse. So, we’ll be looking today at, ­­­how to treat rain rot on horses. 

What Causes Rain Rot

How Rain Rot in Horses Happens

With a name like rain rot, it is no surprise that the disease originates from your horse being out in the rain. Damp, warm weather conditions leave a certain amount of sitting water on your horse’s skin, which succinctly becomes the perfect home for bacteria. If your horse has an open sore, like from a scratch or a bug bite, or a weak immune system, the bacteria gets beneath the skin and starts growing. 

How Rain Rot in Horses Happens

Rain Rot Causes

Scientifically, Dermatophilus congolensis is the bacteria that causes rain rot in horses. Typically, it can be found on a horse with no ill consequences as it simply sits on top of the skin and is removed by regular washing. According to EcoEquine, the problem comes when a horse has a compromised immune system, damaged skin barrier, poor nutrition, poor hygiene or is in a stressful situation. 

Rain Rot in Horses: Diagnosis 

What it looks like

Equisearch says that rain rot on horses begins as multiple small bumps/scabs, which can spread and grow together to form large patches. Scabs will appear tightly adherent to the skin, painful to remove and the hair matted together to form patches called ‘paintbrush’ lesions. They will then come off with the hair and leave bare spots and open sores on the horse. 


How Your Horse May Act

The legions that form from rain rot causes the skin beneath them to die, succinctly, making your horse’s skin very itchy. The horse may be scratching or biting the area to soothe the itch, but this will only spread the disease further. On rare occasions, rain rot on horses can lead to fever, pain, and loss of appetite. 

Official Diagnosis

While rain rot on horses can be primarily diagnosed simply by appearance, there is a method used by a veterinary that can confirm the bacteria present is in fact Dermatophilus. According to Jenny Wilkinson, DVM, in an interview with Stable Management, veterinarians can perform skin scraping and look at the cells under a microscope to see the bacteria.  Apparently, Dermatophilus congolensis has a distinct appearance as they line up in a way that very much resembles railroad tracks. 

Rain Rot Treatment For Horses

The goal of treating this disease is to attack its root cause, which in this case is the bacteria. With the skin scabbed over, sometimes medication can help with the appearance of the problem, but won’t actually be able to cure it. As such, I’d suggest using a combination of shampoo to soften the skin and medication to cure the disease. 


According to Horse & Rider contributing editor and veterinarian Karen Hayes, home remedies can sometimes help a rain rot on horses, but oftentimes, it can make the problem worse. Thus, I firmly recommend you should use topical lotions and washes when fighting rain rot on horses. Without the medicinal properties found in these, the bacteria continues to multiply and harm your horse. 

Over the Counter – Medication

These medications for horses can be found at pet and farm supply stores in addition to being found online.

Over the Counter – Natural Alternatives

These medications are also commonly found, but only contain natural materials and oils to help cure rain rot on horses.

Home Treatment

In addition to the medication used to treat rain rot on horses, there are additional steps you can take at home to improve the process. You can switch your horse to a new feed, like those that have antioxidants, which can help boost your horse’s immune system. You should also try to keep your horse as relaxed and as dry as possible to prevent the infection from keeping hold. 

Listen to Your Veterinarian

As with any disease or infection your horse may have, you should always listen to your veterinarian. They will be the most qualified person to distinguish the symptoms as being from horse rot, a bacterial disease, or a rarer fungal infection, like ringworm. If the scabs and lesions on your horse have grown large, a veterinarian is also indispensable as they have the right tools and skills to remove them with the least amount of pain on your horse. 

Rain Rot in Horses: Prevention

The best way to prevent this in horses is to make sure they are not in the same environment they were when they first contacted the bacteria.  The Practical Horseman recommends some easy steps you can take to prevent rain rot in horses:

  •       Expose your tack and horse to sun-dry
  •       Wash the tack after use
  •       Provide good shelter to keep your horse out of the rain
  •       Use fly sheets during the fly biting season
  •       After bathing, scrape excess water from the body
  •       Apply insect repellent regularly

Prevent Rain Rot if You Can! If Not, Treat it Immediately

Now that you know what rain rot on horses is, what it looks like, how to treat it and how to prevent it, you should feel confident in caring for your horse. If you still have questions on what to do if you see these on your horse, you can always follow ofhorse.com’s steps to treating rain rot on horses. And when in doubt, you should always check in with your veterinarian.


Is rain rot on horses contagious?

Rain rot is not a contagious disease. It is the result of a bacterial infection and requires external trigger to appear, such as:
- rain which washes away the oils on the hair coat
- warm moist environments where bacteria thrive, including wounds, rain rot patches and the folds of the skin.
Rain rot is a bacterial infection which causes hair to break off at the root. The infected area becomes reddened and scaly. In some cases it can lead to a secondary fungal infection known as rain rot fungus. Rain rot appears as reddish-brown spots with a black or dark green centre. The rain rot fungus is more flaky and has a lighter centre.
It is not possible for people or other animals to catch rain rot from horses. However, rain rot fungus may transfer between horses on grooming equipment.

How long does it take for rain rot be cured?

Once rain rot has appeared, the body needs time to produce new skin and hair (hair follicles). This is because rain rot weakens and scars the skin. Until this time rain rot is not contagious. During rain rot recovery, horses are contagious for rain rot fungus. To control rain rot-fungus, you must kill it by applying fungicide cream, which takes rain rot 3 to 5 weeks to heal.
It is important to treat rain rot in the early stages. If rain rot fungus has spread across the body, it can be very difficult for it to fade away.

What complications in horses can cause rain rot?

Septic rain rot or rain rot with secondary bacterial infections is known to cause further complications. These can include:
- rain scald which is rain rot on the buttocks and hocks, which interferes with movement.
- rain rot dermatitis is also known as rain rot fungus or pastern dermatitis. This causes dark, flaky patches on the skin.
- rain rot thrush is rain rot in the lower legs and feet, which makes it difficult for horses to walk.
- rain rot can also infect the hooves, causing an infection in spaces between the toes.
In more severe cases rain rot can lead to development of cellulitis, septicemia and colitis. It can also damage skin around the mouth and cause stomatitis. In rare cases rain rot infection has been known to cause toxemia in foals. This can result in respiratory problems or laminitis.
A horse with rain rot is more susceptible to infections and other health complications due to a lowered immune system function. Horses who have been treated for rain rot are recommended to be vaccinated against respiratory diseases.

Can horses get rain rot on legs?

Horses can get rain rot on their legs. This is also known as rain rot dermatitis, rain scald or rain rot fungus. It appears as a reddish-brown discolouration on the legs and lower body of a horse. In some cases rain skin fungus can spread to other areas including the face and neck.
The rain rot fungus most commonly occurs on lower legs due to moisture accumulating in the folds of skin where rain rot fungus thrives (in warm, moist environments).

Can rain rot cause swelling?

It is very uncommon for rain rot to cause swelling. In cases of rain scald or rain rot fungus, swelling may occur as a result of bacterial infections and inflammation.
In some cases rain rot fungus can infect a small area of the hoof. This can cause a small amount of swelling, but it rarely represents a serious concern.