Rain Rot: Part Two of Water Issues

Rain Rot: Part Two of Water Issues

Although it has been a couple of months since my last post, I still want to continue the conversation about Rain Issues.  Texas has seen a full mixture this year.  Floods, droughts, extreme heat (especially around Christmas), you name it.  We always like to joke that if you don't like the weather, stick around, it will change in a couple of hours.  Last blog we discussed the issues of Hoof Rot, or Thrush in horses.  In this write up I would like to concentrate on Rain Rot.

Rain Rot for horses, also known as Rain Scald in cattle, goats, and sheep, is a very common skin infection caused by the bacteria dermatophilus congolensis. dermatophilis This prickly little organism is an actinomycete, which is fancy for it behaves like both bacteria and fungi.  Once the organism finds it's way to the skin of the animal, Rain Rot typically needs it's preferred weather conditions to multiply.  If I was this microorganism, I would live in southern Florida.  Not just because it's nice to retire there, but because the warm air, plus adequate rainfall, and super high humidity means this little bug can have a full on party.  The infection is not life-threatening, but if the skin condition is left untreated the animal could be susceptible to a secondary infection, such as a staph, which could be much more resistant and serious than Rain Rot. 

So, first things first.  How does one know their horse or cattle has this lovely skin condition?  You might notice that your horse has tiny little matted tufts of hair that are easily plucked off, or you might also see large crust like scabs. These hair issues are most often found on the animal's back, head, and neck.  Rain Rot can also be found on the animal's legs if they stand in wet areas.  Animals with thicker coats are more likely to become infected since their coats typically hold more moisture and take longer to dry.  A horse can be introduced to the organism by sharing equipment with other infected horses (brushes, blankets, leg wraps, etc.), or through the help of those annoying ticks, horse flies, and mosquitoes that transmit the bacteria from one animal to another.  My horse, Skip, got Rain Rot twice in his life and it always manifested itself in patches right on the top of the back, near the base of the tail on top of his rump, and to either side of his withers.  His gorgeous, thick, auburn coat would get those little tufts of hair that would easily scrape off and leave little bumps, and gray skin underneath.  His condition looked something like this:

Rain Rot tufts of matted hair

So now you want to know: How do you treat this unwelcome "rider"?  Although Rain Rot can occasionally disappear on it's own, generally you will have to help your animal by giving it a bath in medicated shampoo.  For mild cases you might be able to get away with iodine-based shampoos and other medicated herbal shampoos that have tea-tree oil.  When crusted scabs are heavily present you might need to seek out a veterinarian's help to get a stronger antimicrobial shampoo or occasionally the vet will place your horse on antibiotics.  Most of the antimicrobial shampoos will advise you to wear gloves and then lather up your horse really well, let it sit for ten minutes and then rinse them off.  Remove most of the scabs that are present using a very gentle hand.  This can be a painful process for your horse, so be gentle and keep in mind that it might take a couple of days to remove all of the scabs.  Depending on your vet's recommendations, some people recommend that the owner wash their horse daily for a week with the above method.  Other experts say wash once then use Betadine or Chlorhexadine for five days to help with the fungal aspect of the microbe. As always use your best judgment for your animal.  If you're not sure about what your horse has or exactly how to treat it, give your vet a call.  A quick slide of one of their scabs under the microscope will either confirm your suspicions about Rain Rot or reveal a different condition that can sometimes masquerade as such.  

What are your experiences with Rain Rot?  Any pointers out there?

Written by Kara Grimes

All information gathered is not meant to act in place of a licensed Veterinarian. Ropes for Less has no affiliation with any of the below mentioned sources and always encourages seeing a licensed Veterinarian before treating.  Information provided by:,, Horse Journal, The Merck Veterinary Manual, and Iowa State University:The Center for Food Security and Public Health.

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  • Burge Linton
Comments 1
  • Doc

    Very informative! Thank you

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