Rain Rot or rain scald is a common equine skin disease caused by a bacterial infection. The source of infection is a bacterium known as Dermatophilus congolensis, which lies dormant in the outer layer of the horse’s skin. When the horse becomes compromised, either by prolonged exposure to high humidity, high temperatures, wetness, or biting insects and the Dermatophilus congolensis reaches the compromised site, the bacterium produces hyphae (threadlike tentacles) that penetrate the skin and spread in all directions.
Rain rot is more common during wet seasons and in geographical locations with high precipitation and humidity, which foster the perfect environment for bacteria to grow. Minor cases appear as dry skin flakes and loose hair. Acute cases present as large matted clumps of hair and scabs that are tender to the touch and difficult to remove. A yellow to greenish pus may be visible around the scabs. Rain rot is mainly found on horses’ necks, withers, backs, croups and lower limbs. These lesions can sometimes be painful for the horse.
Symptoms may include:
- Thick crusted hair
- Warm skin
- Painful to touch
- Raw, sensitive areas
- Matted hair
- Hair loss
The earlier you detect rain rot, the easier it will be to spare your horse the discomfort and cosmetic problems associated with it. Many mild cases tend to heal on their own. However, early or less severe cases should be treated. Antimicrobial shampoos should be used to bathe the horse and remove the scabs. In more severe cases, antibiotic injections by your veterinarian may have to be given.
Rain rot is usually easy to diagnose, but if you are uncertain ask your vet. Unfortunately, we cannot control the weather but daily grooming with clean brushes and keeping your horse dry is the best way to prevent rain rot. It’s extremely contagious and can be spread to other horses through direct contact, grooming tools, or tack. It is best to isolate the infected horse until the rain rot is gone. Grooming tools and tack should be disinfected between each use.
If your horses are turned out all the time, give them a place to go where they can completely get out of the rain. If the climate is very humid, give them a shady place to get out of the sun. You can even set up fans so horses can dry themselves off. Regular grooming to check your horse’s skin condition, particularly if blanketed, is key. While any horse can develop rain rot, horses with weak immune systems are more likely to contract it and may experience a more severe case. Take extra precautions for senior horses and those with compromised immune systems to keep them in dry environments