Rain scald is a bacterial skin infection from prolonged wet. Bring the horse in to dry off, gently lift away loose scabs, clean with a mild antiseptic, and keep the coat dry. Severe cases need the vet.
What rain scald is
Rain scald, or rain rot, is caused by the same type of bacteria as mud fever, taking hold when the skin stays wet for long periods. It shows as crusty, scabby lumps along the back, quarters and sometimes the face, often lifting off with tufts of hair.
Get the horse dry
The single most important step is to break the wet cycle. Bring the horse into a dry, sheltered area, or use a waterproof, breathable rug so the skin can dry. Damp skin will not heal, so drying out matters more than any product.
Treat gently
Once dry, lift away scabs that come off easily and clean the affected skin with a mild antiseptic, then dry thoroughly. Do not force off firm scabs, which is painful and spreads infection. Groom regularly with a clean grooming kit so you spot new patches early, and keep brushes clean to avoid spreading it.
Protect against more wet
Provide shelter, use a well-fitting waterproof rug for horses that feel the wet, and avoid sharing tack or brushes between affected and healthy horses. Good field shelter and drainage reduce the constant soaking that causes the problem.
When to call the vet
If the patches are widespread, sore, or the skin is broken and weeping, or if the horse seems unwell, ask your vet. Bad cases may need clipping and medicated washes, and a vet can rule out other skin conditions that look similar.
