Horse Health: What is Rain Rot?

Rain Rot or Rain Scald

I have seen many cases of Rain scald in horses in Texas – particularly this year (2015) due to the horrendous and constant rain brought about by El Nino in the Pacific. We have been subjected to many more than 40 days and 40 nights of rain this Spring. The paddocks stay wet and muddy. Many times the horses don’t even use the run-in shelters. They don’t seem to mind the rain from above, since it is warm and not uncomfortable. However, they continue to lie in the wet mud and roll in the mud. Additionally the fly population has been bad this year as opposed to other drought years.


I always believed that it was caused by a fungal infection. However, according to Wikipedia, Rain scald is caused by Dermatophilus congolensis, a gram-positive bacteria that is thought to originate from the soil. It commonly causes problems in moist, tropical areas, but can also be found in wet northern environments.

Moisture and high temperatures facilitate the dispersal and penetration of zoospores into the skin, contributing to the spread of the disease. Ticks, biting flies, and contact with other infected animals also causes the spread of rain scald. Once in the skin, the bacteria cause inflammation of the skin as well as the typical symptoms associated with rain scald.

Rainscald normally heals on its own, however as the condition can spread to involve large areas, prompt treatment is recommended. Although some cases can be severe, most rain scald is minor and can be easily and cheaply treated at home naturally. (The pony above contracted a severe secondary infection as well as suffered from an allergy to midge flies that compounded the problems for her)


First groom the affected parts carefully, to remove any loose hair. Be extremely gentle. The area can be very sore (especially in severe cases) and horses will very quickly get fidgety. Next shampoo the area, use warm water and a soft cloth or brush, and massage the lather through the coat as much as the horse will tolerate.

Some of the of the best ingredients for soothing damaged hair coat and skin are Neem Oil, Tea Tree Oil and Aloe. Neem and Tea Tree have long been believed to have antiviral, antibacterial, antifungal, and antiseptic qualities. Aloe soothes and heals and is generally great for allergy-prone horses. We found a great body wash containing organically grown Aloe Vera and Tea Tree Oil. There is also an Aloe and Tea Tree conditioner that can be applied after the bath to continue to treat while the horse is dry.

Remove as much water as possible and dry the horse off (either use a hair drier or let him/her stand in the sun until completely dry). It is important not to let the horse roll! The rain scald bacteria may be picked up from the soil. (This may be the hardest part if your horse is a habitual roller – white horses seem to be the worst – and you don’t have an enclosed stall area during his treatment schedule.)

When the horse is completely dry, gently brush off any more loose hair.

The absolute best treatment we have ever used is called Banixx.
“Banixx® is a wound, skin and hoof care product that is odor-free, non-staining, and sting-free. It is non-toxic, steroid-free, antibiotic-free, and does not contain alcohol or tea tree oils, yet works wonders in any situation where bacteria or fungus are involved.”

The pony in question was treated with an injection of penicillin, a round of treatment with LDN to reduce inflamation, and Banixx every day (sometimes twice a day) for a month. She is now growing her hair back, which we feared would never happen) and seems to be nearly recovered.

Once all the scabs are gone and there is new hair fuzz growing in all over, use the shampoo again to clean the area of greasy residue, and dry well. Keep the horse covered for some time after rain scald has been treated, particularly in wet weather. Do not allow the skin to remain damp. It is advisable to shampoo the horse after riding or exercising, to remove sweat, which may encourage rain scald conditions, and make sure the coat is completely dry afterwards.

This treatment works in many ways. First, shampooing cleans the area of any contaminants, removes a lot of loose hair and scabs, and the rubbing stimulates the circulation. The Tea Tree Oil or Neem is an antifungal agent, and works to eliminate the bacteria that cause the infection. It soothes the irritation in the area, and its greasiness provides the ideal environment for the raw skin to heal and grow new hair. It also helps to soften and lift the scabs. The new hair cannot grow in until those scabs are removed from the surface, but they are very painful to pick and remove, and most horses are intolerant of this procedure. After the neem has soaked into these scabs they will come away much more freely, and soon new hair will grow through.

In severe or chronic cases, penicillin and streptomycin are injected into the horse to kill the bacteria systemically.

Typically the disease is not life-threatening, nor does it impact the welfare of the horse (unless it becomes severe such as in the case of the pony above), so treatments are more for the owner’s peace of mind and cosmetic appeal of the animal.

Please note that this advice is neither veterinary nor prescriptive in nature but offered only as an introduction to this topic.

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2 thoughts on “Horse Health: What is Rain Rot?

  1. We are treating a pony (above in the large image) that appears to have a severe case of rain rot (which the previous owner tells us she gets every summer). I will post pictures of her here in a few days. We are trying Banixx. Results will also be posted here (good or bad)

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