Scratches is a common skin condition in horses that affects the lower legs, particularly the area around the pastern (the joint between the fetlock and the hoof). It causes crusty, scabby, inflamed skin that can range from a mild irritation to a painful condition severe enough to cause lameness. You’ll also hear it called pastern dermatitis, mud fever, greasy heel, or dew poisoning, but they all describe the same basic problem.
Scratches isn’t a single disease with one cause. It’s more of an umbrella term for inflamed, damaged skin on the lower legs that can be triggered by bacteria, fungi, parasites, or simply prolonged exposure to wet and muddy conditions. That’s part of what makes it frustrating to deal with: the same symptoms can have different underlying causes, and treatment depends on figuring out which one you’re dealing with.
What Scratches Looks Like
The condition typically starts with patchy redness on the skin of the pastern or heel area. You might notice the skin looks irritated or slightly swollen before any scabs form. As it progresses, the skin begins to ooze, crust over, and develop painful scabs. The area underneath those scabs is often raw, with erosions or small ulcers.
Swelling in the affected leg follows as the condition worsens. The skin becomes sensitive to touch, and many horses will flinch or pull away when you try to handle the area. Some horses develop noticeable itching and will stamp or rub their legs. Lameness can develop and become severe in advanced cases, especially when the cracks and sores make it painful to flex the pastern joint during movement.
In chronic cases that go untreated for weeks or months, the skin can thicken and become hard, almost like scar tissue. At this stage, the condition is much harder to resolve and may require more aggressive veterinary intervention.
What Causes It
Moisture is the single biggest factor. When a horse’s lower legs stay wet for extended periods, whether from standing in mud, wet bedding, or dewy pastures, the skin softens and its natural barrier breaks down. Once the skin is compromised, bacteria and fungi move in.
One of the more common organisms involved is Dermatophilus congolensis, an unusual microorganism that behaves like both a bacterium and a fungus. It’s the same organism responsible for rain rot on a horse’s body. Other bacteria, various fungi, and even mites (particularly chorioptic mange mites) can also cause or worsen the condition.
Several environmental and management factors increase the risk:
- Muddy turnout areas, especially around gates, water troughs, and feeding stations where footing gets churned up
- Frequent hosing of legs without thorough drying afterward, which keeps the skin damp
- Wet or soiled bedding in stalls
- Minor cuts or abrasions on the heels and pasterns that give bacteria an entry point
Breeds at Higher Risk
Any horse can get scratches, but draft breeds and other horses with heavy feathering on their lower legs are particularly vulnerable. Breeds like Shires, Clydesdales, Belgian drafts, Gypsy Vanners, Friesians, and Percherons have thick hair around the pasterns that traps moisture against the skin and makes it harder to spot early signs of trouble. The heavy feathering creates a warm, damp environment that’s ideal for bacteria and mites to thrive.
These same breeds also face a related but distinct condition called chronic progressive lymphedema (CPL), where the lymphatic system in the lower legs doesn’t drain properly, causing progressive swelling, skin folds, and nodules. CPL produces lesions that look a lot like scratches, but standard scratches treatments won’t resolve the underlying lymphatic problem. If a draft horse develops persistent, treatment-resistant “scratches,” CPL is worth investigating with a veterinarian.
How It’s Treated
Mild cases typically respond well to cleaning and topical treatment. The first step is gently removing the crusty scabs, which can be painful for the horse. Soaking the area with warm water and a medicated cleanser helps soften the crusts so they come off without tearing healthy skin. Once the area is clean, it needs to be thoroughly dried before applying any topical treatment.
Topical creams for scratches usually combine ingredients that fight infection and reduce inflammation. Your vet may prescribe or recommend a cream containing an antifungal, an antibacterial, and a mild steroid to calm the irritated skin. Over-the-counter options exist, but because scratches can have different causes, a product that works for one horse may not work for another.
More severe cases, particularly those involving significant swelling, lameness, pain, or fever, may require systemic treatment. This typically means oral or injectable antibiotics along with anti-inflammatory medications. The key signal that a horse needs more than topical care is when the infection has moved beyond the skin surface and the horse is showing signs of systemic illness.
When Scratches Becomes Dangerous
The biggest concern with untreated or poorly managed scratches is cellulitis, a deep bacterial infection of the soft tissue beneath the skin. The cracks and sores created by scratches give bacteria a direct route into deeper tissue layers. A horse with cellulitis develops dramatic, hot, painful swelling that gives the leg a “stovepipe” appearance, uniformly thick from top to bottom. The skin may crack under the pressure of the swelling, develop abscesses, or begin seeping fluid. Fever is common.
In severe cases, the swelling becomes what’s called pitting edema: if you press a finger into the swollen tissue, it leaves an indentation that stays. Some horses accumulate so much fluid that serum starts oozing through the skin surface. Cellulitis needs aggressive veterinary treatment and can become a recurring problem if the underlying scratches isn’t properly managed.
Preventing Scratches
Prevention centers on keeping the lower legs clean and, more importantly, dry. In muddy conditions, managing the environment matters more than managing the horse’s legs. Put down gravel or another hard surface in high-traffic areas like gates and around feeders. Rotating pastures or dividing fields into sections so heavily churned areas can rest and dry out helps significantly.
One of the most counterintuitive pieces of advice: resist the urge to hose mud off your horse’s legs every day. Frequent washing actually worsens the problem by keeping the skin chronically damp. Instead, let the mud dry and brush it off. If you do wash the legs, dry them thoroughly afterward.
The question of whether to clip feathered legs is a judgment call. Removing the feathers makes it easier to see early signs and keep the skin clean, but in some horses, the feathering itself acts as a protective barrier that prevents mud from contacting the skin directly. You’ll need to experiment to see what works best for your horse.
Barrier creams and turnout boots can help keep legs dry, but they come with a caveat. If a barrier cream seals moisture against the skin, or if turnout boots get wet and aren’t changed, you’re actually creating the exact warm, damp conditions that encourage bacterial growth. If you use boots, swap them out regularly before they become saturated.