Rain Rot

[Trish Dowling <dowling@skyway.usask.ca>]

> 
> Date: Thu, 30 Jul 1998 06:55:09 EDT
> From: BeckeG@aol.com
> To: ridecamp@endurance.net
> Subject: Rain Rot
> Message-ID: <60d9caf1.35c0510e@aol.com>
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> 
> Help.  I don't know what to do any more.  We have a horse that has had some
> form of Rain Rot for the past 6 months.  The vets said to use Betadine on it
> until it is gone. But, it is not going away.  Some days it looks like it is
> growing.
> 
> Does it get worse before it gets better?  I figure you folks have a wealth of
> information that might help this horse.  Your insight would be appreciated.
> Its funny, too. Because this little section of Michigan has had no rain for
> over 2 months.  So how come "Rain" Rot is growing with no rain?
> 
> Becke Grams & Rocky
> MW  
************************************

1) Are you washing the Betadine off? The worst skin lesions I've seen are from people putting Betadine scrub on 
rain rot lesions and not washing it off thoroughly and turning the horse out in the sun. Iodine will fry their skin.

2) Rain rot is caused by Dermatophilosus congolensis - a higher bacteria. Didn't quite make it to a fungus. 
Therefore is is sensitive to antibiotics. Penicillin, Naxcel and Trimethoprim sulfas will all work against it. See your 
vet about trying one of these. Bathing with an antibiotic shampoo is helpful, as long as you rinse it off well. I've also 
used Topazone (nitrofurazone) spray on the lesions on horses in the wintertime that I couldn't bathe. Good 
grooming is essential for removing scabs and getting oxygen to the affected areas.

3) The organism is part of the normal flora of a horse's skin. Some horses carry higher numbers on their skin than 
others. When the skin is moist and cracked, the organism forms motile zoospores that actually swin down into 
the cracks. The horse then mounts an immune response and you see the lesions. Some horses are more 
sensitive to the organism than others and blow up worse. But 6 months worth is unusual. If you've tried all of this, 
it may be worth having your veterinarian take a skin biopsy and have it submitted to a pathologist to check for 
other weird dermatological diseases.

Good Luck.
Trisha


Trisha Dowling, DVM, MS, Diplomate ACVIM & ACVCP
Associate Professor, Veterinary Clinical Pharmacology
Western College of Veterinary Medicine
Saskatoon, SK S7N 5B4
306-966-7359/FAX 306-966-7376