Rain Rot in Horses
By: Dr. Lydia Gray | Updated March 21, 2025 by SmartPak Equine
What is Rain Rot in Horses?
Rain rot is a skin infection caused by the bacteria Dermatophilus congolensis. Although the bacteria is present in the environment all the time, it requires a moist environment and a break in the skin to develop into the characteristic hard, painful crusts over a horse’s back and rump.
These crusts are distinctive not only because of where they occur on the horse’s body, but also because when removed, hairs stick through the scab and look like a mini "paintbrush." Rain rot is an unsightly condition that may also prevent a horse from being worked until the skin heals.
Treatment for Rain Rot in Horses
The best treatment for rain rot is removal of the scabs so that dry air and sunlight can reach the skin. Since the crusts are hard and painful, it may be necessary to soak and soften them first with an antibacterial bath. Horses that are severely affected or ill may also need injections of the antibiotic penicillin.
Preventing Rain Rot and Other Skin Conditions
Although some horses are susceptible to Dermatophilus no matter how well they are cared for, certain steps can be taken to try and avoid the infection.
- Groom horses daily, especially those wearing blankets.
- Keep all tack, brushes, and blankets as clean as possible and try to not share equipment between horses.
- Provide shelter from the rain, especially in the winter.
- Make sure all horses are up-to-date on vaccinations, deworming and other health care, and that they are at an appropriate weight.
Video on Rain Rot in Horses
In this Ask the Vet video, Dr. Gray explains what rain rot in horses is and how to prevent it from spreading throughout the stable.