Monday, October 7, 2013

Ask An Expert | 10/7/2013

Ask An Expert | Your Questions About Horses

By: Pam Gleason


This column answers readers' questions about horses. Anything is fair game, from questions about equine health to how to get along with the other boarders at your barn, to general horse keeping.

Dear Expert,

What's the best way to treat rain rot? My horses are turned out this summer, and with the amount of rain we've been getting, they all have rain rot. One of them has it pretty bad. How do I get rid of it and can it be prevented?

                                                                                                     -Hate Rain Rot

Dear Hate Rain Rot,

Rain rot, otherwise known as rain scald, is popping up around Aiken this summer and we got quite a few questions about it. Before we get to this question, here's a quick summary of what rain rot is:
Rain rot is an infection of the out layers of the skin caused by bacteria called Dermatophilus congolensis. These bacteria are quite widespread and are assumed to be present in the soil. Dermatophilus doesn't generally give any trouble unless the weather is wet and humid, which causes the bacteria to become more active. Horses generally get infected after they have been out in the rain, which is where the descriptive, ugly name comes from. Other animals can also get rain rot, according to Merck Veterinary Manual. In sheep it is called lumpy wool disease, and in cattle it can be a serious problem, especially in Africa. It's common in crocodiles in Australia, and the books say that people can get it, though we have never heard of a human with rain rot.

When a horse is first infected, he might be covered with little bumps, usually on the back, hindquarters, neck and anywhere that rain gathers and runs off. If the infection progresses, those bumps get larger and harder, and eventually form scabs and crusts. When the scabs fall off, they take tufts of the horse's hair with them, and may have pus underneath them. Horses can have a few scabs  here and there, or they can be covered with them. In early stages, rain rot doesn't appear to cause the horse much distress, but when the scabs form, they can be quite painful. If the lesions are under the saddle area, they can make a horse unrideable, and if they are present in any significant amount, they can definitely ruin a horse's coat and overall appearance. Summer rain rot is usually not as bad or as ugly as winter rain rot, though there are exceptions.

So, that explains what rain rot is. Now, what can you do about it?

We posed this question to Dr. Tom Stinner, a veterinarian who practices at Southern Equine Service in Aiken. Dr. Stinner says that rain rot has been a problem this year because of the constant moisture.

"It isn't just the rain rot," he says. "Humidity and sweat can also keep the skin wet. Moisture, combined with dirt in the horse's coat, form a film on the skin that can act as an incubator for bacteria."

If your horse has a mild case, Dr. Stinner says that there are many topical creams and ointments you can use. "But a lot of it is just to clean it, to get the dirt off and loosen up the scabs which are protecting the bacteria. You want the scabs to come off so the areas of infection can dry out."

Dr. Stinner recommends using a mild disinfectant wash, such as Betadine or Nolvasan scrub or shampoo. After the horse is clean and dry, you can apply an over-the-counter ointment or cream to the affected areas. These do not have to be strong or heavily medicated ointments, since what you are mostly doing is helping the skin to heal, and softening any scabs that are still there.

If the horse has a severe infection, or it doesn't respond to tropical treatment, Dr. Stinner says that adding antibiotics is often necessary. "You should call your vet if the horse's skin is very sensitive, or you are treating for several days and you don't see a response, or the scabs are very widespread. The bacterium is sensitive to Penicillin or SMZs [sulfamethoxale], and sometimes we might use an immune stimulant. We would combine these medications with topical treatment."

Dr. Stinner says that if a horse has a stubborn or especially severe case, there is often an underlying cause.

"It might be a cause of poor nutrition, so that the horse's immune system is compromised. Horses with Cushings [a hormonal disorder] often will get nonresponsive rain rot because their immune system is knocked down. In those cases, treating the underlying problem is important."

Can you prevent rain rot? If you can keep a horse dry, sure. But it is not easy to keep a horse dry in the summer in Aiken. If they are not getting rained on, they are often sweating. The best way to prevent an infection from getting started is to make sure that the horse stays clean, though as Dr. Stinner remarks, bathing a horse frequently is a doubleedged sword, since you do want to keep a horse clean, but you don't want to make him wet all the time. Early treatment is the key to preserving his coat and appearance.

"In the summertime we often get calls about a horse having hives," says Dr. Stinner. "A lot of times, it turns out that it's not hives at all; it's rain rot. If you start treating the horse immediately, you can often keep a case from progressing to the stage where there are scabs and the hair falls out."

Since rain rot is so common, there are quite a lot of home remedies for it. Some of them work, some don't, and some work, but might be at the cost of your horse's comfort, well-being and general attitude. On the Internet, people swear by bathing horses in bleach solution, Pine Sol solution and ammonia solution. Others say you have to curry the horse very hard to scrape off all the scabs and then treat them with something powerful and caustic. Dr. Stinner says that these remedies might work, but are generally overkill and not recommended.

"Aggressively cleaning the skin with something strong might work, but you have to be careful. The horse's skin might be irritated and sensitive and if you put something on it that is too harsh, you may kill some of the bacteria, but you are likely to make the horse more uncomfortable and you might slow down the healing process."

Dr. Stinner says that some milder home remedies and prevention tactics might be helpful. Some that get the stamp of approval from farm owners in Aiken include rinsing a horse with a Betadine solution after a rain, or misting his coat with a Betadine spray. Many of the expensive over-the-counter remedies that work well have mineral oil as a main ingredient. Some horse owners swear that plain mineral oil or baby oil works all by itself, without the need for antibacterial agents or disinfectants.

"This could be because the oil loosens up the scabs, and then seals and protects the skin," say Dr. Stinner. The downside is that a horse with baby oil on him looks greasy, and if he has light-colored skin or has lost a significant amount of hair, the oil could accelerate a sunburn. The upside is that baby oil is inexpensive and not painful for the horse, so that grooming remains a pleasurable activity for him - more aggressive tactics often result in a horse that runs off in terror when he sees you coming with a curry comb.

So the bottom line is: keep it clean; and if those things don't work, call your vet. The bacteria that cause rain rot are not usually very difficult to kill as long as you a diligent, so always remember to treat your horse's skin like the sensitive organ that it is. Good luck!

This article is copyrighted and first appeared in The Aiken Horse. It is reprinted here by permission.