Page 76 - Speedhorse December 2019

“If your winter is wet and muddy or alternately dry and wet, this is tough on skin.”
by Heather Smith Thomas
There are a number of skin problems and infec- tions that affect horses, some of which are more frequently seen in winter and wet conditions. Dr. Greg Evans, co-owner of Moore Equine, near Calgary, Alberta, says that in his practice the follow- ing are several common skin problems he deals with.
SCRATCHES
“I think inconsistency in weather and a constantly changing environment can be harder on the skin than a more consistent climate. If your winter is wet and muddy or alternately dry and wet, this is tough on skin. If horses are standing in mud or have to walk through muddy areas in their pen or pasture, scratches is the number one skin condition we deal with. There are several names for this, including greasy heel and mud fever. The medical term is pastern dermatitis,” says Evans.
“The cause is not always known, but it occurs most frequently in wet conditions. We think there is likely some micro-trauma to the skin of the pastern— maybe a nick or abrasion. In winter, the skin might be broken by ice or crusted snow. If moisture is held against the damaged skin by hair, especially in horses that have a lot of hair on the lower legs, this seems to make them more susceptible,” he explains.
The precise causative organism has never been definitively cultured. “It’s usually a mixed bag of bacteria and fungi that are present in the mud and fecal material the horses are standing in. It starts as a wet rash on the leg/pastern/heel area and then becomes a crusted scab. The lesion can spread aggressively. In our practice, scratches tends to most commonly affect horses with white legs.” Pigmented skin seems to be a little tougher and less readily nicked and scraped. Horses with white “socks” usually develop lesions only on the white legs.
“There are differences of opinion regarding treatment,” says Evans. “In my practice, I like to sedate
the horse and clip the legs to get all the debris and crusted hair removed. Sometimes I can do this with just a salve containing moisturizers, antibiotic and a little bit of steroid, to soothe the sore pasterns and soften the scabs so we can lift them off. Then we can clip around the area.
“I clean the affected area with chlorhexadine soap and thoroughly dry the legs. I tell clients that it is very important to dry the area very well with a towel or hair drier. One of the problems with scratches and why it lingers for weeks is that clients are continually washing the lesions and leaving the legs wet. Because the microbes that cause scratches have an affinity for wet conditions, this delays healing.”
This is also good reason to not bandage the area. “Some people like to bandage the leg after cleaning
it and applying medication, but I personally prefer to leave it open,” he says. “A bandage holds moisture and exudates against the skin. I prefer it to be dry. If the environment/management is such that the feet cannot be kept dry because the horse lives outside in the rain and mud, it becomes a real problem.
“If there’s opportunity to keep the legs dry, I like to meticulously dry the lesions and keep the horse indoors in a dry stall, with good hygiene so there’s not much urine and ammonia in the bedding. If possible, we let the horse out on a nice paddock where the sun can get to the lesions and where the feet are not buried in mud.”
Scratches can be frustratingly slow to heal and may come back again. “Typically I don’t use antibiotics unless the horse is exhibiting other signs of subcutaneous infection like significant limb swelling or lameness associated with the scratches,” he says. “In early stages,
I just use local treatment with topical ointments. But keeping it clean and dry is most important.
“The other group of horses in which I see a lot of scratches is show horses or any horses that are bathed a lot. They aren’t standing around in muddy
WINTER SKIN PROBLEMS IN HORSES
Scratches, or pastern dermatitis, occurs frequently in wet conditions on the lower legs. Scratches begins as a wet rash, then becomes multiple firm nodules and sometimes a crusted scab.
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SPEEDHORSE, December 2019
EQUINE HEALTH