Is your horse more likely to have scratches than another? Learn what predisposes her to this escalating skin reaction, and what you can do to prevent its onset and treat it before it gets worse.
Pastern dermatitis in its milder form is often called scratches or mud fever. As it worsens into an exudative (fluid emitting) state, it is also called dew poisoning or greasy heel. Pastern dermatitis is an inflammation of the skin on the pastern, between the fetlock and hoof. It is a syndrome of an underlying condition rather than a specific diagnosis, and as a result, it can have many causes. The fungus Sporotrichum schenki is often the culprit, but pastern dermatitis can also be caused by ringworm, mites, or an infection of the hair follicles with Staphylococcal bacteria. It is therefore important to get to the root cause to determine a proper course of treatment. As scratches progresses, it can become chronic and incredibly painful, infecting the deeper layers of skin in the heel, fetlock and pasterns. In mild cases, it makes your horse sore and tender; in more advanced cases, your horse will not want to move and will become lame.
Scratches often begins as a fungal infection that results in a secondary bacterial infection. The fungus thrives on organic matter and finds its way into tiny breaks in the horse’s skin. It begins as a small pinkish ulceration in the plantar pastern and develops into sores with black crusty scabs that can ooze pus and cause hair loss and edema. If left untreated, bacteria can invade inner tissue and even vascular and lymphatic vessels. When this occurs, the whole lower leg may swell and can often lead to lameness.
Factors that put your horse at higher risk
Climate or moisture
Horses that spend copious amounts of time in damp muddy pastures, or who are frequently exposed to heavy early morning dew, are prime targets. This is because the skin on their lower legs, pasterns and heels is subjected to a constant wetting and drying that robs it of natural oils. The process leaves the skin dried out, flaky and undermined. Once weakened, it’s easy for some small infection to take up residence — and the next thing you know, your equine has a case of scratches!
Hygiene and work environment
Scratches is a frequent pesky infection that often inflicts show horses, since they generally receive more baths than their pasture counterparts. They also tend to work in rings and other warm moist environments where large quantities of manure have intermingled with the sand base over time. The gritty sand alone can irritate the sensitive skin and cause micro-tears for the bacteria to enter. Poor stable hygiene is another contributing factor.
Breed and color
Scratches is more common in equines who have white legs or socks because the non-pigmented skin is more susceptible to chafing and abrasion, opening the way for infection. This malady is confined to a horse’s lower limbs because blood flow in the legs is somewhat weaker, and good blood flow is essential for rapid, reliable sustained healing. Feathered legs, which are found predominantly in heavier breeds such as drafts, draft mixes or Gypsy Vanners, can also encourage scratches. Heavy feathers set up the perfect storm for infection since they trap dirt and moisture.
Other sources of irritation that lead to scratches include insects and parasites that cause irritation and subsequent infection; and dry cracked skin that is continually aggravated by the horse’s movement.
Treatment for scratches
Your vet may wish to take a skin scrape or culture to determine the exact cause of the rash, but initial treatment is standard. Clip any excess or long hair away from the infected area (taking care not to break the skin) to keep the area clean and dry. Do not attempt to pick off the scabs unless advised by your vet; these are nature’s protective Band-Aids and their removal will not only be painful for your horse, but leave the skin at risk for further infection – they will fall off with treatment. Gently wash the affected areas with mild soap or a medicated shampoo. Pat the areas dry and apply a gentle, odor-free, non-stinging anti-fungal and antibacterial topical treatment. You may finish the process by applying an antimicrobial wound care cream that contains marine collagen and acts like a protective moisturizing barrier over the area.
When treating pastern dermatitis, your goal should be to eradicate 100% of the infectious cells; otherwise, the organisms will mutate and continue to thrive. Because of this, some approaches involve the use of harsh chemical mixtures, often containing iodine, alcohol or tea tree oil. A more benign approach as outlined above will generate more success. The problem with the harsher approach is that the mixtures themselves are often drying and irritating, so you’re less likely to continue using them for the full course of treatment. These treatments can also cause your horse considerable discomfort if they burn or sting, and will cause him to become difficult to treat. These issues may result in less consistent treatment and a prolonging of the infection.
For best results, keep your horse in a dry clean environment for as long as possible. However, make sure he is also able to readily move, since movement will stimulate blood flow and subsequent healing. As always, consistency of treatment is key to good results, and daily attention is a must for success.