Disclaimer: The following is only general information. If you believe that your horse has a problem please call your veterinarian as soon as possible.
This condition, which can also be called dermatophilosis, is a bacterial infection of the skin along the top line of the horse. It is usually found in paddock horses when the weather is wet or humid. The bacteria that causes this condition can be the same as Mud Fever/Scatches, however the time of year and the location of the infection is different. Also mites and fungus are not involved in Rain Rot, although biting insects could be.
Rain Rot usually appears along the neck, withers, back and rump as scabs. These can range in size from pinpoints to large scabby areas that have joined together. When you remove the crust or scab you will find a yellow/green pus between the dead and living skin layer and the hair will lift off.
Although it usually starts along the top line it can move down the sides, of the horse, and onto the legs.
Rain Rot or Rain Scald is not itchy, however it will become inflamed and tender to touch.
Cause and Treatment
Long periods of wet weather, high humidity, high temperatures or attacks by biting insects can cause cracks or punctures in the skin.
Bacteria called Dermatophilus congolensis, which lives dormant within the skin layers, can now enter the damaged areas.
Spores that are created by the bacteria help it multiply and travel to other damaged areas of skin.
The spores germinate and produce threadlike tentacles, which penetrate into the living skin and spread in all directions.
This inflames the skin, making it sore to touch.
It is best to treat even minor cases as the sores can spread rapidly. Also the location of these painful sores usually means that you cannot use a saddle or ride the horse. This is a highly contagious disease.
Remove the affected horse(s) from unaffected horses until you have treated it and all sores have stopped forming scabs and have healed
For less severe case, remove the scabs and wash with antimicrobial shampoo. Gently curry and groom with clean brushes. You may also use a diluted iodine scrub, however this may dry out the skin so after you have let the scrub dry use a antibacterial cream or ointment to sooth the skin as well as kill the bacteria
For more serious cases where deeper skin layers are affected your veterinarian may recommend antibiotic injections.
Regularly inspect your horse with your eyes as well as your hands to feel for any scabs or rough skin.
Regularly inspect all the horses in the same paddock – remember it is contagious.
Keep rugs clean and do not share rugs with other horses.
Make sure that rugs are rain proof – wet rugs are worse than no rug.
If possible use light-weight breathable cotton rugs in hot, humid weather to deter biting insects.
If possible do not share grooming tack with other horses.
Clean and disinfect your grooming tack after each use.
Try to reduce biting insect populations – harrow pastures to dry out manure, slash long grass, do not leave water standing in buckets or trays for mosquitoes to breed, and purchase fly traps for your stable and yard areas.
This condition can be transmitted to humans and other animals so wash your hands thoroughly after treating your horse and disinfect any cut that you may have.
The above information is only general in nature. If you believe that your horse has a problem, please call your veterinarian as soon as possible.
Severe Rain Rot