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Is Horse Rain Rot Contagious?

Horse owners spend enormous amounts of money and time ensuring that their horses remain healthy. It is discouraging to discover that your horse has oozing scabs on its body that appeared to come out of nowhere. Investigation reveals that your horse has rain rot. Your immediate concern is whether rain rot is contagious and if your other horses will develop the condition.

Horse rain rot occurs as a result of infection with bacteria called dermatophilus congolensis. The bacteria can be transmitted to other horses through direct contact, indirect contact, and insect vectors such as flies, mosquitoes, and ticks. Humans are also vulnerable to infection.

Many people think rain rot is an isolated condition that affects only one individual. This nasty infection can be transmitted to susceptible individuals making them sore and uncomfortable.

What Is Rain Rot In Horses?

Rain rot or rain scald is a bacterial infection caused by the bacterium dermatophilus congolensis, which causes a condition known in scientific circles as dermatophilosis. There are a number of other names for rain rot.

  1. Streptothricosis
  2. Rain scald
  3. Contagious dermatitis

The same bacterium causes a skin condition of the feet known as mud fever or strawberry foot. 

What Are The Symptoms Of Horse Rain Rot? 

Rain rot is usually seen on the topline or back of a horse but may also occur on the groin, face, scrotum, udder, and armpits. The bacteria cause lesions which weep or ooze fluid which then hardens to form scabs.

There is hair loss in the affected area, which may extend over a considerable portion of the horse’s body. The tissue under the scabs is inflamed, and if the scab detaches, a raw bleeding painful wound is exposed.    

Rain rot can appear as strawberry red scabs or wart-like growths in severe cases, or the horse may look moth-eaten with patchy hair growth. It is a painful condition that may cause the horse to scratch on trees and fence posts, exacerbating the skin damage.

Although some people think of this as a minor condition, it can become so severe that the horse may die.

How Do Horses Get Rain Rot? 

Horses get rain rot during the rainy season when there is rain for extended periods, and the horse does not have a chance to dry. Dermatophilus congolensis occurs naturally on many horses’ skin and does not cause a problem. It is only when the skin is damp for extended periods that the bacteria multiply.

Mud fever develops when horses’ feet are constantly wet. This can be a challenge as often the horses get wet feet from dew without the presence of rain. Horses that have feathers of their legs and feet are particularly prone to mud fever.

During the rainy season, there is an abundance of biting flies, mosquitoes, and ticks. The tiny openings in the skin caused by the bite of these pests allow the bacteria to enter the body and begin multiplying. Wounds and scratches are also a potential entrance for the bacteria.

Once inside, the bacteria cause a breakdown of the skin and tissue inflammation, resulting in an exudate that forms the scabs when it hardens.

How Is Rain Rot Transmitted From One Horse To Another? 

Dermatophilus congolensis is bacteria with an unusual life cycle as it more closely resembles a fungal life cycle. These bacteria produce spores just like fungi do, and these spores can be spread by various means.

  1. The spores can be present on scabs and hair that fall off an infected horse. Another horse that comes into contact with the scabs and hair is at risk of developing rain rot.
  • As you can imagine, grooming an infected horse with the same equipment used to groom non-infected horses will spread the bacteria quickly.
  • Horses like to groom each other by biting gently at each other. Any horse doing this with a horse infected with dermatophytes congolensis could develop rain rot.  
  • Biting flies and ticks can transmit bacterial spores from one horse to another. When they bite a horse, they provide an opening for the bacteria that they have carried.

Are Some Horses More Prone To Rain Rot?

Some horses always seem to get rain rot, and others never seem to get it even when they are in the same paddock. Several different factors can affect whether a horse develops dermatophilosis.

  1. Horses with a compromised immune system will be more prone to developing rain rot. This would include elderly and young horses.
  2. Horses with seasonal allergies that compromise the skin will also be more likely to get rain rot.
  3. Any horse with an open wound will contract rain rot easily if there is another horse with rain rot in the herd.
  4. A horse with a thick coat that does not dry easily will also be susceptible to dermatophytes congolensis.

Where Do Horses Get Lesions From Rain Rot?

Horses get rain rot lesions mostly along their top line, but they can get the lesions in other areas such as the face, rump, and neck.

Lesions induced by biting flies are often seen on the topline neck and face. In contrast, those that are the result of tick bites are usually seen on the feet, in the groin, udder, scrotum, and armpits.

Horses are often prone to getting rain rot lesions in areas where riding tack is in contact with the skin. It is worsened by ill-fitting saddles and bridles or dirty tack, which may rub sores on the horse.

What Are The Complications Of Horse Rain Rot?

The skin is the first line of defense against bacteria and fungi that may penetrate the skin. When a horse has rain rot, the skin barrier is compromised, making the horse more vulnerable to infections by other organisms.

It is common for horses with rain rot to develop secondary bacterial infections, particularly staphylococcal folliculitis. This condition presents as pus-filled papules, which can lead to large areas of disease in the skin.

Staphylococcal folliculitis is painful, uncomfortable, and compromises the horse’s health. A problem has arisen where some forms of staphylococcus are unresponsive to commonly used antibiotics.  

Ringworm is a fungal infection that will sometimes appear in conjunction with rain rot. Ringworm is contagious and spreads from one horse to another and to people who care for the horses.

Horses with severe cases of rain rot may lose condition, become emaciated and even die from associated complications such as colic. If the rain rot is on the lips, nose, and muzzle, the horse may not eat or drink due to pain.

Rain rot or mud fever on the feet can be so uncomfortable that the horse will not walk or move around to graze and becomes at risk of developing colic and laminitis.

How Is Rain Rot In Horses Treated? 

Rain rot should be treated as early as possible before the condition has an opportunity to progress. It is treated in two ways in horses – namely, management and medical treatment.

How Do You Manage Horses With Rain Rot?

It is essential that the horse has a chance to dry out properly. Providing shelter or stabling reduces the risk of rain rot and helps the horse’s natural immunity fight the bacteria. It is vital that the stabling or shelter has dry flooring if mud fever is present.

Insecticides should be used as chemical barriers to prevent biting flies and ticks from stinging or biting the horse. These stings and bites provide entrance points for the bacteria and irritate the skin causing allergic reactions and inflammation.

Horses with rain rot lesions should not be worked, and all tack should be cleaned and disinfected before being used again. 

Soaking the lesions in warm water to remove scabs is helpful. Chlorhexidine is a beneficial antiseptic that does not irritate or burn and can be used to clean the affected areas. Antibacterial shampoos aid in killing spores and bacteria.

What Medicines Help For Rain Rot In Horses?

Dematophilus congolensis is susceptible to many commonly used antibiotics. These include:

  1. Erythromycin
  2. Penicillin
  3. Chloramphenicol
  4. Amoxicillin
  5. Tetracyclines

It is best if the animal has systemic antibiotics as well as topical antibiotic applications on the lesions.

Pain control is essential when dealing with rain rot in horses. Topical applications of antibiotics can be mixed with local anesthetic creams. Non-steroidal anti-inflammatory medications can be used for pain relief but must be used judiciously to avoid the risk of gastric ulcers.

Corticosteroids may be preferred as they reduce inflammation and relieve itchiness which may worsen lesions if the horse scratches itself. It is important to remember that corticosteroids and non-steroidal anti-inflammatories should not be used in conjunction unless stipulated by your veterinarian. The use of the two together commonly results in gastric ulcers.

How Do You Prevent Rain Rot In Horses? 

For many years, people assumed that rain rot occurred only in neglected horses that did not receive proper care. This is not always the case, although neglected horses are, of course, more prone to various conditions, including rain rot.

An essential factor in preventing rain rot is to detect the beginning stages of rain rot as soon as possible. Early detection can be achieved by daily grooming, which allows you to inspect the horse visually and by touch.

Sometimes you may not see the initial lesions, but you will feel them. Treating rapidly helps prevent bacterial spread on the infected horse and between horses. Grooming your horse daily removes loose hair. Loose hair in the coat prevents the horse from drying once it is wet.

In rainy seasons, it is advisable to ensure that your horse has the opportunity to dry out thoroughly. If your horse lives out, it may be a good idea to invest in a horse raincoat, waterproof horse sheet, or rug. Not only will this keep the horse dry, but it will also be a mechanical deterrent to biting flies.

Horse-safe insecticides should be used to deter flies, mosquitoes, ticks, and other pests that may bite, sting, or irritate the horse’s skin. The use of insecticides must be carefully considered. Insecticides should not be overused as this could compromise the horse’s immune system, making it more prone to issues such as rain rot.

In areas where ticks are a severe issue, preventing them from biting the horses can be challenging. Cutting the grass in paddocks and encouraging birds such as guinea fowl or other insectivorous birds can help to reduce the tick population.

Some horse owners have even adopted the habit of keeping a flock of chickens around the stable yard or in the paddock to limit the tick load. Natural insecticides such as neem oil may be a valuable alternative to toxic insecticides.   

Does Clipping Help Prevent Rain Rot?

Clipping your horse may help prevent rain rot if it has a thick coat that does not dry quickly. The flip side of clipping, though, is that clipped horses are often easier targets for biting insects. Short hair makes their skin more accessible to insects.

In climates where rain occurs during winter, clipping the horse may make the horse less able to deal with the cold. Some owners prefer to clip and then rug their horses.

Some people find that clipping only certain areas is helpful. In cases of mud fever, cutting off feathers around the legs and feet can be beneficial.  If you enter your horse in showing competitions, you cannot clip the feathers and need to find another solution.

Do Other Animals Get Rain Rot? 

Most mammals are susceptible to dermatophilosis. It is found in domesticated livestock, such as sheep, pigs, and cows. Rain rot has also been found in wild animals, including deer, rabbits, various rodents, buffalo, woodchucks, skunks, camels, apes, and bears.

The implication is that if dermatophilosis is present in your farmyard animals or wildlife in your area, you must be diligent in managing your horse to avoid it becoming infected.

Can People Get Rain Rot?  

People can be infected with dermatophilus congolensis if they are in contact with an infected animal and have an open cut, scratch, or lesion of some kind. Fortunately, people are not usually damp all the time and dry out once they are indoors.

Dermatophilosis in humans is not usually a severe condition. However, immune-compromised individuals may struggle more to throw off the infection.

You can avoid contracting the bacteria by using gloves while treating an infected animal and washing your arms and hands thoroughly after contact.


A bacteria called dermatophilus congolensis causes rain rot. The bacteria can be transmitted from one horse to another in a herd. It can also be transmitted between species, and people can contract it from dealing with infected horses.

It is treated by management to control insect vectors and dry out the horse’s skin and coat. Antibiotics, corticosteroids, and non-steroidal anti-inflammatories are helpful drugs to treat rain rot.


Anrie Diedericks

I've been around horses since I was 6 years old and started competing at the age of 9. Horses are my greatest passion and I am thrilled to be able to share my 23 (and counting) years of experience and knowledge with you.

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