Diagnosing, Treating, and Preventing Rain Rot in Horses

During periods of heavy rainfall many horse owners may notice the emergence of rain rot in their horses. This skin condition can be frustrating but with proper care it is often manageable.
Rain rot is especially prevalent during rainy seasons so its important for horse owners to understand how moisture can affect their horses skin health. While it is typically treatable prompt action is essential to prevent the condition from worsening or spreading.
Also known as rain scald or dermatophilosis rain rot is caused by a bacterium called Dermatophilus congolensis. While this bacterium usually remains dormant on the horses skin it can become active in wet conditions leading to inflammatory infections that produce lesions. These lesions manifest as small raised bumps covered with scabs that may contain hair clusters. When these scabs are removed they can leave behind bald patches in the affected areas. In more severe cases the lesions can grow larger and penetrate deeper layers of skin necessitating a break from riding until the infection resolves.
While most often found on the horses topline rain rot can be found on numerous other areas of the horses body including the rump face and legs. Therefore it is important that regular thorough fullbody examinations occur. Handson palpation may be needed when examining for rain rot particularly during winter months as increased coat length makes visual assessment difficult. Unlike many other skin conditions areas with rain rot do not typically itch but can be painful and cause the horse to become sensitive to touch.
All horses can be affected by this condition however links with horses coat colours and immune status leading to a higher incidence of rain rot have been identified. Particularly horses with lighter coat colours as well as horses with compromised or poorlydeveloped immune systems such as young or older horses have been found to be at higher risk. Specific environmental factors have also been identified. Rain rot most often occurs when the skin has been compromised in some way. Compromise occurs during times of high humidity prolonged rainfall or increased exposure to biting insects. Horse owners should take steps to limit