It’s a cool rainy fall day, and you’re looking forward to a nice ride in the indoor arena on your beloved equine pal. Perhaps you’ve had a busy work week and haven’t seen him in a few days. As you bring him in from the pasture and park him in the cross ties, you absently run your hand along his back and give him a loving pat. To your dismay, your horse’s typically fuzzy soft coat feels lumpy and crusty and he flinches at your touch. What on earth is this?

“Rain rot” (also known as rain scald or Dermatophilosis) is an all-too-common problem for our equine companions. Affected horses typically develop lesions along their topline and hindquarters, and the infection can often be identified by its characteristic “paintbrush lesions” formed by healing scabs. Severe cases may lead to secondary infection with other bacterial species, and the skin can become very inflamed and painful.

Shampoo should be diluted with warm water and gently lathered into the affected skin. For best results, let sit for 10 minutes before gently scrubbing again to loosen softened crusts, then rinse thoroughly. Initial treatment can be done daily or several times per week - consult your veterinarian for their individualized recommendations. 

In severe cases resulting in fever or depression, or for those that simply fail to respond to treatment, it is time to involve your veterinarian. Some atypical cases require further diagnostics such as skin scraping or culture to identify the underlying cause. Your veterinarian may also recommend systemic antibiotics to treat severe secondary infections. 

Preventing Rain Rot

As they say, an ounce of prevention is worth a pound of cure. Ensuring your horse has proper nutrition and regular preventative health care will help support a strong immune system. As the weather and pastures become more wet and sloppy, be sure that your horse’s skin is protected from constant moisture. He should have access to a shelter, and you may elect to use a dry, waterproof turnout sheet or blanket on particularly wet days. 

Regular grooming will help clear moisture-trapping mud and debris from the skin, and will allow you to catch early signs of a problem. Be sure to avoid sharing grooming tools between horses when dealing with an active infection. Regular, thorough cleaning of brushes, tack, saddle pads, and blankets can also help prevent infection and transmission between horses.