Horse Journal OnCall: Severe Scratches Won't Heal

Pastern dermatitis requires knowing the cause and treating it appropriately and gently.
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Pastern dermatitis requires knowing the cause and treating it appropriately and gently.

I have a 15-year-old Spotted Draft stallion. He has small areas of scratches on all four legs. The worst one is behind his right knee. I have had to vets treat him over the years, and it is managed but never clears. If I don't wash his legs weekly then apply Lime Plus Dip with a spray bottle then it gets really bad. We've also used antibiotics, medicated shampoos, betadine, and a mixture of nitrofuracin, cortisone and DMSO.

Fetlock feathers can hold in moisture and dirt, setting the stage for pastern dermatitis (Thinkstock photo).

Fetlock feathers can hold in moisture and dirt, setting the stage for pastern dermatitis (Thinkstock photo).

The Lime Plus Dip keeps it in check, but sometimes the sores will break open. His paddock is mostly dry, and he has a 12x12 rubber matted stall with clean dry shavings. I shaved his feathers off a long time ago.

I am considering another shampoo, but I'm not sure if it's right. Here in Northern New Hampshire, I have no other veterinarians in the area to consult. I have had my horse since he was seven months old, and I adore him. I've been a subscriber for years. Can you help me?

Contributing Veterinary Editor Grant Miller, DVM, responds: Thank you for writing into HJ OnCall about the ongoing skin problems that you are having with your draft horse. You are not alone since this ailment affects many breeds of horses all over the United States. It has gone by many names over the years, including scratches, grease heel, and grapes. Veterinarians call it Pastern Dermatitis, and it can be caused by several factors including bacteria, fungus, and in rare circumstances, parasites.

The condition is nearly ubiquitous in the Friesian breed as well as in most draft horses. This is thought to be due to their long feathers, which keep the affected areas from being exposed to air and light. However, as you mentioned in your description, even with the feathers clipped, the condition can persist.

Be aware that genetic researchers are confident that this skin condition has a genetic component. This means that the horse's DNA is coded to either predispose or cause the condition to occur. Although the exact gene mutation has not been mapped, there are efforts being made to identify it. What does this mean to you? It means that very likely, no matter what you do, you will be managing an ongoing issue rather than curing it.

So, how do you manage Equine Pastern Dermatitis?

  1. Rule out any causes such as bacterial infection, fungal infection, or mite infestation (again - the third one is VERY rare). You will need your veterinarian to help you. He or she will take skin samples and have them tested.
  2. If a cause an be elucidated, treat it appropriately. Bacterial infections generally are treated with topical and/or systemic antibiotics. Fungal infections are generally treated with topical and/or systemic antifungal medications. Parasite infestations are generally treated with topical and/or systemic parasiticides.
  3. Keep conditions optimal: Clipping hair and keeping the environment clean and dry are beneficial.

What should you NOT be doing?

  1. You should not be apply treatments such as Listerine, iodine, scarlet oil or, repeated use of topical parasiticides. These chemicals severely irritate the skin, which only worsens the condition and causes the horse significant discomfort.
  2. Do not vigorously scrub skin. Skin is a delicate organ, and a good rule of thumb is to treat it like a piece of silk. Cleaning should be gentle - picking, peeling, and scrubbing hard and long should be avoided.
  3. Don't try products on the skin without veterinary advice. Many horse owners have pushed their horses into full-blown lymphedema (elephant leg) by causing severe inflammation to pastern dermatitis on a repeated and ongoing basis. While a horse can live with pastern dermatitis, they generally cannot live with lymphedema.

Finally, don't give up hope. We recognize that you are doing your best with the resources that you have and that you are devoted to trying to help your horse. There are thousands of horse owners just like you trying to manage Pastern Dermatitis in their horses too. Unfortunately, it appears as time goes on that there is an underlying genetic component to this condition that causes certain horses to be prone to it.

Closing thought: There are some great products on the market that combine topical corticosteroids, antibiotics, and antifungal medications all into one topical ointment. They are designed primarily for use in dogs with ear problems, but they can provide relief for horses with pastern dermatitis. Ultimately, they reduce inflammation, slow down bacteria, and stop fungus. Talk to your veterinarian about their ongoing use in your horse. While they are somewhat expensive, they seem to work.