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Combating common equine skin problems

February 24, 2020

Hives (pictured here) can be somewhat of a common occurrence, especially in horses with more sensitive skin. Fortunately, they rarely impact general health and typically resolve on their own within a few days.

Spring is often accompanied by warmer temperatures, excess moisture and the reemergence of biting insects. While the more moderate weather can often feel like a welcome relief — especially after a long, cold winter — this aptly monikered “mud season” can wreak havoc on a horse’s skin and coat. Conditions like rain rot, scratches, sweet itch and hives are more than just unsightly and uncomfortable — they can also have a significant impact on your riding and training time.

Of course, we all know that horses are naturally sensitive beings and that skin problems are never 100% avoidable. Attention to proper grooming, nutrition, supplements and veterinary care can make a big difference, but we should all be prepared to recognize and treat these issues when they manifest. Let’s explore four of the most common ailments, as well as some recommended treatments and steps you can take to help keep them at bay.

Rain rot in horses

  • What causes it? As the common nickname for this pesky dermatological disease implies, rain rot is brought on by a combination of moisture and the presence of a bacterium called Dermatophilus congolensis. Every horse is susceptible to this condition, which is generally associated with warm, wet weather. Broken skin, either from bug bites or cuts, allows the bacteria in. Excess moisture also plays a significant role because it strips the skin of natural oils that otherwise serve as protection from bacteria.
  • How do I identify it? If your horse has rain rot, you’ll notice scab-like bumps, particularly along the top of the head, neck, back and/or croup. When pulled, the hair will easily come away from the body, leaving behind an infected, hairless spot of skin. These lesions are commonly itchy or painful.
  • Is it contagious? Yes, rain rot can easily spread from one horse to another. As such, it’s important to not share brushes, blankets or tack, and to make sure these items are regularly cleaned.
  • How do I treat it? While often mistaken for a fungal disease like ringworm — which is, thankfully, far less common — this bacterial condition will not be affected by antifungal medication. Bathing the horse with an antibacterial shampoo, removing the scabs once they have softened and following up with a topical antibacterial treatment can prove effective.
  • How do I prevent it? Groom your animals daily and clean your brushes often. You should also take several environmental factors into consideration. Shelters are great in theory, but how many times have you witnessed a horse standing outside of a shelter during inclement weather? As horse owners know, equines are sadly not always concerned about self-preservation! If it’s raining, provide a protective waterproof sheet (which must also be regularly cleaned, especially if your horse is symptomatic) or leave your horse in a stall for the day instead.

Scratches in horses

  • What causes it? Also known as mud fever or pastern dermatitis, this condition is often produced by a mixture of bacteria that commonly includes Dermatophilus congolensis, Staphylococcus spp and/or fungal organisms known as dermatophytes. It may also be caused by parasites. These organisms find their way into breaks or openings on the horse’s skin, and the prime conditions during which they are likely to appear include consistent exposure to an excessively moist or dirty environment. As with rain rot, every horse is susceptible to scratches; however, those with feathers or long fetlock hair that retains moisture seem to be particularly vulnerable. Horses with white legs may also be more at risk, since unpigmented skin is more susceptible to sun damage, chafing and abrasions.
  • How do I identify it? Early symptoms often include swollen skin and small, scab-like bumps. If allowed to progress, you’ll notice scabby crusts forming on the back of the pastern, which often appear in a line that looks like — you guessed it — a scratch. Although scratches most often impact the hind legs, horses may get it on their front legs as well.
  • Is it contagious? Yes, this is also an easily transmissible disorder. Do not share boots or grooming supplies, and practice good hand hygiene, especially after coming into contact with the infected area.
  • How do I treat it? Carefully clip the hair away from the affected area and gently wash it with an antibacterial or antifungal shampoo. Begin by doing this once daily for the first 7–10 days and cut back to two or three times per week until the issue is remedied. Let the shampoo sit for approximately 10 minutes before rinsing. Scabs can be massaged off gently, but you should not pull or pick at them. Carefully pat the area dry with a clean towel before applying a topical antibiotic or antifungal treatment. Keep your horse housed in a clean, dry environment.
  • How do I prevent it? Keep footing as dry as possible, and get into the habit of drying your horse’s legs before you put them into their stall. Don’t share boots or wraps, and, if possible, keep feathers closely trimmed.

Sweet itch in horses

  • What causes it? Also known as summer itch, this seasonal recurrent dermatitis is typically caused by an allergic reaction to Culicoides, a genus of biting midges. You may commonly hear these pests referred to as “no-see-ums” or gnats. Horses may also experience insect hypersensitivity in response to biting flies. This hypersensitivity is considered the most common allergy in horses and is a typical reason for itchy skin.
  • How do I identify it? Horses with sweet itch often become very itchy in the spring and may rub out their mane and tail hair. You may also notice skin irritation or lesions along the topline, jaw, axillary regions and ventral midline.
  • Is it contagious? No, but other horses on the property may also be susceptible to the negative effects of these biting insects.
  • How do I treat it? Antihistamines, topical creams and insect repellents may be effective options and should be tried first before resorting to more serious measures, such as corticosteroid injections, which can have serious long-term side effects with prolonged use.
  • How do I prevent it? Remove manure regularly and keep standing water in check. Use stall fans and fly gear, such as masks and boots, and keep in mind that “no-see-ums” prefer to begin feeding at dusk and overnight, so keep at-risk horses inside during these times.

Hives in horses

  • What causes them? Many things can cause hives, including insect bites, pollens, food allergies, medications or direct contact with a variety of materials.
  • How do I identify them? Also known as urticaria, hives are fluid-filled, raised swellings on a horse’s skin. Generally round in shape, these bumps may range in size from 0.5 to 8 inches wide. They may or may not be itchy and can develop anywhere on a horse’s body, though they most commonly appear on the neck, back, flank or leg area.
  • Are they contagious? No, hives are not transmissible.
  • How do I treat them? Fortunately, hives rarely impact the general health of a horse and often resolve on their own within 24–48 hours. In these cases, treatment is unnecessary. However, in more severe cases, you may wish to consult with your veterinarian on treatment options, such as antihistamines, epinephrine or corticosteroids.
  • How do I prevent them? It can be difficult to determine the root cause of hives, but avoidance or the elimination of triggering factors can play a key role in keeping them from reoccurring in the future. This may involve some trial and error, but suggested steps include changing paddocks and bedding and eliminating supplements one at a time to determine whether they may have been a culprit in causing this allergic reaction.


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