Treatment and Causes of Rain Rot in Horses, Dogs, and Cats

What Is Rain Rot?

Rain rot (also known as rain scald, dew poisoning, dermatophilosis, or mud fever) is a common and highly contagious skin infection that occurs in dogs, cats, horses, cattle, sheep, and a wide variety of wild animals. It is caused by dermatophilus congolensis, a facultative anaerobic bacterium.

This type of bacterium can use oxygen when it is available or switch to anaerobic metabolism (fermentation) when it is not. D. Congolesis generally affects the epidermis. The bacterium causes the skin to scab, resulting in hair loss.

What Causes Rain Rot?

• While it can occur at any time during the year, it generally proliferates in high heat and humidity.
• Dense winter coats also provide ideal conditions for dew poisoning.
• I have also found that waterproof bug sprays lock moisture to the skin, which can exacerbate rain rot infections.
• Just like with other bacterial infections (e.g., pink eye), the horse can reinfect himself from other areas of his skin.

Best Treatment for Rain Rot

The single best way I have found to treat rain rot is to use an antibacterial shampoo (containing chlorhexidine, betadine, or benzoyl peroxide) or antifungal shampoo (containing 1-2% miconazole) in the following way:

• Rinse your animal thoroughly.
• With a gloved hand and medicated soap, feel for and remove all scabs. Generally, you will find pink, inflamed skin behind those scabs. Scab removal has been shown to increase healing times.
• Make sure to look behind the legs, around the ankles, and on the insides of the legs.
• If your animal has a thick coat, you may need to clip hair away from infected areas to better reach scabs.
• Let the shampoo sit on your animal for 10 minutes.
• Remove and throw away your used gloves.
• Rinse your animal.
• Then, wash your animal a second time.