Witch hazel and listerine!
Uh ohhhh I️ hate rain rot, it’s the worst!! You either have to mix a solution together and scrub the scabs everyday or (better solution) get some banixx.
Rain rot also has to do with sudden change of weather. One of our ponies had it but when it got sunny again it went gradually away, it came because the weather’s humidity was very high.
The cause of rain rot also known as rain scalt is sharing equipment and tack with other horses.
To prevent it is to make sure the horse has its own equipment (tack, rugs, numnah and grooming kit), good groom, keep rugged up, clean grooming kit.
Treatment is to clean affected area with antiseptic scrub, antibiotics or penicillin.