Every horse, no matter how carefully managed, is likely to get some sort of fungal or Dermatophilus infection sooner or later. Usually called “rain rot,” this skin condition is commonly found on horses maintained outside in times of high rainfall, especially if they have thick, winter coats. 

It tends to be worse in animals that are debilitated or on a poor plane of nutrition, but it can strike any horse. The organism thrives in the warm, moist conditions against the skin. However, it can also occur as a result of bug bites. The same organism (Dermatophilus) also can cause a severe heel dermatitis (scratches).

The lesions begin as multiple small bumps/scabs, which can spread and grow together to form large patches if not detected and treated early. The scabs are tightly adherent to the skin and painful to remove. They come off with the hair and leave open sores. Once the scabs are off and medications can get to the skin level itself, healing is usually rapid.

A variety of treatments have been used. Iodine shampoos and other medicated or herbal shampoos with tea tree oil may work on mild, early cases, but when crusting is heavy the most they can usually do is slow the appearance of new lesions. The combination of EQyss Micro-Tek shampoo and Gel is good for mild to moderate cases as well but may not penetrate heavy areas of scab.

A dirty, wet horse can have rain rot hiding beneath their winter coat.

For spot treatments of Dermatophilus on the lower legs and as scratches, or for areas of thick scabbing elsewhere on the body, we like the application of Triple J Sheath cleaner. Wet the area and leave it on five to 10 minutes then rinse. Crusts may come off after a single treatment. The animal can then be bathed with a tea-tree-oil shampoo and open areas protected with a tea-tree-oil-based cream.

Another popular treatment is sprayed on Listerine, and EQyss suggests their Micro-Tek Gel can be used alone, in lieu of having to bathe the horse first and remove scabs. See our chart for details on these treatments and more. Note: Never combine products with different types of active ingredients.

Also highly effective is the antifungal dust, captan (see sidebar, page 17). Bathe the horse to remove surface dirt and any loose scabs, then a use a 1:300 strength rinse, which is poured on and excess removed with a scraper then left to dry. Some vets advise to just sprinkle the dry powder on the horse while still wet from the shampooing. Captan is an EPA-registered fungicide, intended for garden use, so be sure to follow safety instructions on the package. Captan should never be used around the horse’s eyes, as it is a severe eye irritant.

FUNGUS
In the fungal category, horses can get ringworm, a highly infectious fungus that can also be transmitted to people. Ringworm infections are circular lesions that start as an inflamed and scaly area, very itchy, which grows out from the center. Because of how easily it is spread, ringworm is best treated with antifungal medications. Captan works well on ringworm, or you can use a topical antifungal cream from your vet or a human product made for fungal foot or vaginal infections. There are also prescription antifungal shampoos for cases that are too widespread for spot treatments.

Other fungal species can also cause problems, especially on the face and at the tail base. They typically do not cause as intense an itching. The lesions are hairless patches with varying degrees of scaling  but are not as angry looking as true ringworm and are slow to spread or enlarge. These less serious fungal infections usually respond well to iodine shampoos, EQyss Micro-Tek system or tea tree oil products.

When present on the head, where shampooing is problematic, we like the Tea Tree ADE cream. This is very thick product that stays in place well without running and does an good job of fighting fungus.