Rain Rot: Common Skin Condition Contagious, but Easy to Treat

Rain rot, rain scald, even dew poisoning—it’s all the same thing no matter what you call it. Caused by bacteria that has fungal characteristics and lives in soil, it is the No. 1 skin condition in our horses.

Our horses live in dirt, roll in dirt and splash in mud puddles (a lot like little kids), exposing them to bacteria. This ugly malady is most severe in moist climates, but don’t be fooled—it shows up in our area too. It is commonly observed during between December and March. Long winter coats also assist the growth of rain rot, a likely reason it shows up more so in winter months around here.

Rain rot is a contagious disease—infected animals can infect others. Of course, some animals are more susceptible than others. Jane is more prone to “scratches,” which is basically the same thing as rain rot but shows up on the legs of horses. Jane battles it all the time, while none of the other horses in my care have ever shown a sign of it. 

Rain rot typically shows up on the back of a horse and is not usually really painful. Like scratches, it is preventable and treatable since it is basically the same thing. The little bugger that is the cause is an anaerobe. Simply stated, it lives well and thrives in low-oxygen environments. It is most easily spread from horse to horse by saddle blankets and grooming tools.

The affected area can have a dull look or may even look very dirty, even muddy or greasy. If you were to pull on the hair, little clumps would come out and most likely have little scabby crusts on the ends. If not treated promptly or correctly, the hair can begin to fall out. 

Saddle blankets are expensive and hard to wash, and I know most of us only have one, maybe two. We leave it with the saddle in the tack room when not in use and throw it onto the next horse we ride. Maybe your trainer uses his or her saddle and blanket on your horse when working her. Do you know for certain that every horse is free from rain scald that has worn that blanket? Something to think about. 

Is it a habit for you to groom each of your horses on the same day, using the same grooming tools? I don’t tend to have the time to do that, and each of my horses has color-coded grooming tools: Cricket has pink, Jane dark blue, Cooper light blue and Teddy Bear is going green. If I can’t find a needed brush or sweat scraper in a designated color, my easy fix has been to have a grooming tote for each horse in my chosen color with the horse’s name written on it, and keep all tools and supplies separated that way.

Another thing to consider is cleaning your grooming tools, at least occasionally. If the bacteria gets onto your grooming tools you can re-infect your horse just by brushing her. 

Another likely but ignored spot that may increase the spread of rain rot is scratching posts. Cricket likes to rub against the pasture fencing to scratch her itches, Jane has me do it for her, and the boys roll in the dirt.

Well, guess what? The fence, my hands and the dirt can all house the little germy guy that could infect the other horses. Yuck!

Even poor nutrition can play a role (remember, calories do not equal nutrition). Lowered immune systems, even in horses, make illnesses difficult to fend off.

Rain rot typically shows up on the back or rump of a horse, which I find interesting since I notice that when Cricket is wet, her back dries first. Her belly and legs dry last. This begs the question: If the back on a horse dries first, why would rain rot show up there most frequently?

Answer: Because the hair holds more dirt and moisture. Even though it looks dry on top, the hair is longer and thicker on her back, thus the bacteria thrives best there.  

Prevention is key, but if you do spot a problem, treatment is pretty simple. Wash the affected area with soap and water—or Betadine Scrub is fine too—and remove all the scabby hair mats that you can to allow air to reach the skin and keep it clean and dry. You may have to let the soap sit for a few minutes to help loosen the scabs, then gently pull them off.

Rinse really well and dry with a soft cloth. Use a little antiseptic ointment or other preparations available at your local feed store, if needed. Keep your horse as clean and dry as you possibly can. The worse your horse’s case is, the more diligent you must be to get rid of it. 

Horses can be carriers and not show a single sign of rain rot, a very common occurrence in the horse world, but not the end of the world. Prevention and good care along with good nutrition, clean hands, grooming tools and a saddle pad for each animal are the best ways to ward off the scabby hair-loss infection.