The skin is the largest organ on a horse, accounting for roughly 18% of its body weight. While the skin is susceptible to an assortment of maladies year round, several are most prevalent during the springtime rainy season. Skin inflammation, or “dermatitis”, is an all inclusive term for aggravated by external irritants, burns, allergies, trauma or infections (bacterial, viral, parasitic or fungal). Dermatitis can be a systemic disease as well.
The most common sign is scratching followed by redness, swelling, and appearance of bumps. It progresses to oozing, crusting, or scaling lesions. Any suspected skin condition should be addressed by your vet as it is important to determine the cause. Diseases can appear the same but treatment can be very different and a proper diagnosis and treatment can save time, money, and the intensity of the condition.
Scratches
Scratches are also referred to as pastern dermatitis, dew poisoning, greasy heel, or mud fever. It is not a condition but rather a description of a problem seen on the lower limbs. It can be viral, bacterial, fungal or parasitic. Risk of contracting this condition increases if the horse is in wet or muddy conditions. Those with light or white skin seem to be more susceptible.
The skin may appear itchy, flaky, sensitive or swollen. Chronically infected horses may have granulomas present.
Treatment should begin as soon as possible. Be gentle, as the area may be sensitive. The best treatment is to keep the skin dry. Remove the horse from the wet area or mud, clip the surrounding hair, and wash the area with an antibacterial soap or Betadine scrub daily. Thoroughly towel dry the area.
Do your best to keep the horse out of the wet and out of tall grass during and after treatment. Stall him up, keep him in a covered arena, or bandage the affected area, using Corona
Severe cases require application of an antibiotic or antifungal ointment and dexamethasone therapy.
Be diligent about disinfecting boots, wraps and grooming equipment.
Thrush
Thrush is a common infection of the hoof that usually affects the tissues of the frog adjacent to the sulci (deep grooves).
It is a common misconception that thrush is only caused by dirty or unkempt environments (which it can be), but in fact thrush can and does occur in the cleanest of conditions.
There is a myriad of elements causing thrush, including abnormal hoof growth, poor shoeing, poor diet/exercise, chronic lameness issues, or poor frog circulation – basically anything that disrupts the horse’s built in cleaning mechanism.
The process of a horse’s hoof cleaning itself can be seen when the limb supports weight. The sole normally becomes flat and the coffin bone descends upon it and expands the frog. This in turn flushes out any substances which may lie in the sulci. Problems begin when the debris are not removed.
Diagnosis is fairly easy –a thick, black, putty-like, foul-smelling material is seen on the frog and in the suici.
This infection is generally easy to manage at home, after a blacksmith or vet trims any dead tissue from the area. The affected foot should be picked out and cleaned daily and any number of topical remedies may be applied, either commercial or homemade.
Over the counter products like Thrush-X or Kopertox and homemade topicals can be applied, including a bleach/water solution (not recommended, as it can often affect healthy tissue), or Sugardine (table sugar mixed with Betadine to form a thick paste).
There are a variety of ways to apply the medication – medicate the hoof and keep it dry, soak the affected hoof in a bucket, tub or medication boot, or, if the horse absolutely cannot be kept out of the wet (or if it is a severe case), soak gauze with the treatment of choice, pack it into the hoof, and wrap. Leave it on 1-3 days before removing. Repeat if necessary.
It is important to involve the vet when treating thrush in order to identify the cause, especially if several horses are affected or one horse becomes chronically affected.
While not a common side effect, thrush can cause permanent lameness if it invades the white line, sole and sensitive tissues. However, most of the time prognosis is excellent with meticulous care of the hoof. Keep the feet picked out and the frog healthy and begin treatment as soon as thrush is suspected.
Rain Scald
Rain scald/rain rot is a dermatitis that affects horses, cattle, sheep, goats and even humans. It can be acute or chronic but is most commonly seen after rainy weather. Infected animals are considered the primary carrier of this bacteria, and it is believed the infection is triggered when the skin is compromised, as in the case of prolonged wetting, increased humidity, high temperatures or insects. Heavy rainfall softens superficial layers of skin and allows an easier path for infection. Natural immunity is hereditary.
Frequently, lesions are seen on the rump, loin, and saddle area. These lesions appear like large drops of scalded skin and often involve the legs.
Exudate (fluid) mats hairs together in plaques (clumps). The actual plaque is small (1mm – 2 cm) but may cover large areas. These clusters will clump out and may have a paintbrush affect in appearance. These plaques can be tender to the touch and when removed, a moist, pink, bleeding lesion is revealed.
The exudates may appear as a yellowish-green pus, or gray and gelatinous in texture. Older lesions may be painful where scabs were removed.
A tuft of hair matted at the base to form a scab covered with exudate is highly indicative of rain scald. Positive diagnosis is determined through culture and/or laboratory examination of the cluster.
Clusters can be potent for an extensive length of time (up to 42 months). Disinfection of equipment and facilities is crucial as well as proper disposal of any crusts, as rain scald is easily spread via contaminated clippers, grooming equipment, or wet lesions. Ideally, these crusts should be incinerated.
Lesions which are dry, hard and cracking respond well to antibiotic or steroid topicals like neomycin or hydrocortisone.
The horse should be bathed with a special iodine shampoo, lime sulfur, or chlorhexadine bath for several days prior to crust removal. A diluted mineral oil can be sprayed on to soften crusts and aid in removal. Many horses recover spontaneously in four weeks.
Unlike ringworm, rain scald is not itchy. The best cure is sun and dry weather. Severe or chronic cases should be treated with antibiotics such as penicillin or streptomycin.
Researchers are still working to determine if bacteria responsible for rain scald live in the soil.
Ringworm
Ringworm is not a worm at all; rather it is a fungal infection seen in warm, damp, dirty or poorly ventilated conditions. The fungus causes skin inflammation when toxins are introduced and the horse experiences a hypersensitive reaction. It is transmissible to humans.
Horses contract ringworm by direct contact with an infected horse, person, soil or equipment. Rodents have been known to transmit this condition as well. Younger or older horse populations, as well as those who have suppressed immune systems, been on prolonged antibiotics or immunosuppressive therapy appear to be predisposed to this condition.
Typically, multiple areas of scaly, crusty patches of hair loss spread (mainly where tack contact is – i.e. girth area), usually in a circular pattern. It is also seen on pasterns.
At first, the lesions may resemble fly bites and can be painful. They may keep expanding for 4-8 weeks and retreat as immunity develops.
The affected area should be clipped and topical treatments applied. Treatment with oral medication griesofulvacin for 30-60 days is recommend. Lime sulfur baths can be beneficial.
Horses should be isolated to prevent transmission and these horses need to be handled after handling all others. Careful cleanup should occur after contact, as human transmission is possible.
Set aside separate saddle pads, girths, bandages and bathing tools for these horses during outbreaks. As with other easily transmissible disorders, all equipment, feed and water tubs should be thoroughly disinfected.
Prompt Action
The best treatment for skin afflictions is prevention, and if an affliction is diagnosed, prompt attention to deal with it. Any skin issues should be immediately addressed. Involve your vet to prevent wasting time or money on incorrect treatments and to prevent escalation within the single horse and also to the herd.
Treat the horse with your choice of topical daily for five to seven days, then weekly to keep future outbreaks in check.
Skin conditions, while usually not complicated, can quickly intensify and/or progress to other animals in the herd. Good management practices, along with a watchful eye, can halt skin conditions before they get out of hand.
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