Scratches: The Latest Treatments for an Old Nemesis
By Paula Danovsky
If you’ve ever come across scratches, you may already know some of its aliases—greasy
heel, mud fever, and dew poisoning, to name a few. Combined, these aliases form a
dictionary-like description of this painful, persistent dermatitis found on a horse’s heels and
pastern backs.
Characterized first by swollen, red, cracked skin, scratches often develops into painful,
oozing, crusty scabs that smell markedly sick-sweet. Left untreated, a horse may experience
localized hair loss and lameness.
Heading For a Breakdown
Scratches develops for many reasons, some obvious and some rather insidious. For example,
riding in a wet, rainy environment exposes a horse to mud and standing water, causing dirt
and debris to collects on his lower legs. Keeping a horse in a dirty, wet pasture or stable also
exposes his legs to negative elements. Any time the skin softens, a horse’s legs are targets for
microorganisms, which act as this syndrome’s changing agents.
“Scratches can ultimately involve the growth of several different kinds of bacteria and fungi
(yeast), but the first step is a break in the skin caused by chapping from wet to dry to wet
conditions. Opportunistic organisms then multiply and cause infection,” according to Dr.
Lydia F. Gray, DVM, MA. She is the Medical Director and Staff Veterinarian for
SmartPak™, a leading marketer of name-brand animal supplements, supplies, and gear.
Other factors in scratches formation can include contact allergies, leg trauma, poor nutrition,
photosensitivity, insect bites or allergies, immune disorders, and a nasty little parasite called
the Choriptes mite.
Dr. Christine Rees is a board-certified Veterinary Dermatologist with San Antonio
Veterinary Referral Specialists in San Antonio and Hill Country Equine in Boerne, Texas.
She’s researched and treated many animal species in relation to dermatology. With scratches,
she says the skin infection can be secondary to contact allergies. Wood shavings used for
bedding or the rubber and dyes in a horse’s leggings and boots can sometimes bring on skin
reactions.
“Contact allergies are not that common with scratches, but it does happen,” says Dr. Rees.
“Normally with these allergies, I will notice symptoms on all four legs.”
Some theories suggest horses with white markings get scratches easier than horses with dark
markings; this stems from a belief that white (non-pigmented) skin is more sensitive than
colored (pigmented) skin. Some just say scratches is easier to see on a white-legged horse
than on a dark-legged one.
Additionally, some research cites higher incidences of scratches in draft horses versus other
breeds. This may be due their trademark feathers. “If the horse is in a wet environment,
moisture can get trapped in the legs,” says Dr. Rees. “Some draft horses, in particular, have
long leg hair.”
With so many variables—from environment to infecting agents—scratches can be difficult to
treat. The best advice, by far, is to start at the beginning and determine why the skin broke
down. If these environmental factors aren’t corrected, any treatment steps become irrelevant.
“I try to get a thorough history to figure out what is setting the dermatitis off,” says Dr. Rees.
“That means first getting the horse into a dry stall, keeping him out of wet pasture, and
possibly switching shavings.”
The Invasion
When a horse’s skin is cracked and exposed, bacteria and fungi gain an easy path to entry.
Once they’ve invaded, they tend to multiply and irritate the skin. This explains the oozing
and crumbliness found with scratches. Common organisms found in scratches cases include
Dermatophilus congolensis and Staphylococcus spp. The fungus Sporotrichum schenkii is
also a noted invader.
Dr. Rees takes a cytology (swab) when examining this dermatitis, and highly recommends
that other veterinarians do the same. With her results, she can see if yeast and bacteria are
present. She may even do a fungal culture. At this point, she can prescribe an accurate and
effective treatment plan for clients.
Before you treat your horse, keep in mind that scratches gives your horse a lot of pain and
swelling! Dr. Gray says, “While there is some pain in the early stages, once there are breaks
in the skin and hard crusts form, every heel-to-toe step stretches the back of the pastern and
opens up the lesions.”
Fighting Back
For every ten ointments and sprays on the market claiming to cure scratches, there are ten
more. Unfortunately, what works for one horse may not work for another. This is one of the
most frustrating aspects of scratches.
As you treat your horse, remember to keep his legs dry, since any moisture-holding
opportunity will exacerbate the lesions. You goal is to destroy infecting agents and start
healing the skin cells.
1. Clip hair surrounding the affected areas. This prevents additional dirt from gathering around
the infection sites.
2. Wash affected areas with a chlorhexidine solution, soaking the leg(s) for at least 10 to 15
minutes. You’ll want to soak lesions long enough to soften the scabs. Chlorhexidine is a
highly effective topical antiseptic that kills gram-positive and gram-negative microbes. It’s
commonly sold concentrated, so you’ll need to dilute accordingly. Only do this step once, if
possible.
3. Pat legs dry. Do not rub.
4. Gently remove scabs with clean hands or sterile gauze. If they don’t fall of, don’t pull them
off; this will be painful to your horse, and his skin is already damaged. You can try this step
again in a few days to remove remaining scabs.
5. Twice a day, apply a topical ointment that has anti-bacterial, anti-fungal, and antiinflammatory properties. Make sure your horse’s skin is clean and dry when you re-apply, so
you don’t lock in more dirt and moisture. Gently wipe the old ointment off first.
6. After the swelling and redness have subsided, apply a gentle barrier cream several times a
day, wiping off old cream each time. Popular barrier creams include petroleum jelly and zinc
oxide (40%).
According to Dr. Gray, most products with a combination of anti-bacterial, anti-fungal, and
anti-inflammatory properties can inhibit epithelial (skin) healing. For this reason, she
recommends switching to a mild cream during the final stages of treatment—to provide a
layer of protection against any further chapping.
Frugal Home Remedies
Ichthammol is an old-time scratches remedy, still popular because it kills bacteria, reduces
redness and swelling, and provides a protective barrier. It’s also one of the more economical
topicals available, an important consideration for the penny-pinching horse owner.
“I have successfully used ichthammol on scratches,” says Dr. Gray. “It not only acts as an
antiseptic and drawing agent, but also protects the area against further chapping.”
“Some people use Desitin®,” says Dr. Rees. “This can be helpful because it soothes, it’s an
anti-inflammatory, and it contains aloe, which has a small amount of anti-bacterial and antifungal properties. It also has vitamin E, which is an antioxidant.”
Remember too, that air and sunshine are good for the skin but bad for infecting
microorganisms: use this to your advantage. Dr. Rees recommends leaving legs to the open
air instead of wrapping them. The only time you’d want to wrap the legs, she says, is in a
situation where you can’t avoid wet, muddy conditions.
Focus On Prevention
Your horse’s recovery will vary depending on his case’s severity and your attentiveness to
treatment. Horses who’ve gotten scratches once are more prone to getting them again.
Consider these tips in your care routine:




Groom your horse regularly to promote skin and coat health.
Don’t share grooming supplies and tack. Keep affected horse’s equipment isolated,
disinfecting when possible.
After washing your horse, dry the legs to prevent chapping.
Apply a barrier cream before your horse enters a moist, muddy area.
Special Thanks To:
Dr. Lydia F. Gray, DVM, MA. Dr. Gray is the Medical Director and Staff Veterinarian for
SmartPak™.
Dr. Christine Rees, DVM, DACVD. Dr. Rees is a board-certified Veterinary Dermatologist
with San Antonio Veterinary Referral Specialists in San Antonio and Hill Country Equine in
Boerne, Texas.