Polo Players Edition

SEP 2018

Polo Players' Edition is the official publication of the U.S. Polo Association. Dedicated to the sport of polo, it features player profiles, game strategy, horse care, playing tips, polo club news and tournament results.

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16 POLO P L A Y E R S E D I T I O N E Q U I N E A T H L E T E BY HEATHER SMITH THOMAS BAD REACTION M any horsemen give injections to their horses. These include vaccinations, antibiotics, and sometimes other medications. Most injections are given intramuscularly but there are a few medications that should always be given intravenously. Intramuscular injections occasionally cause local abscesses if the needle or skin was dirty when the injection was given. Sometimes abscesses occur even with very clean conditions, however. The worst kind of injection-induced infection is called clostridial myositis or myonecrosis. This type of infection is caused by certain types of clostridial bacteria that are present in the environment. Some of these bacteria live in the horse's intestines and don't cause problems under normal conditions. They are present in manure, and form spores that last a very long time in the environment. They are often on the horse's skin and can be taken into the tissues with an injection. These bacteria can be in a dormant state, and then multiply when conditions are right; they grow best in an airless environment without oxygen, such as bruised and damaged tissue with very little blood supply. The dormant spores "come to life" and become dangerous when they find favorable conditions in which to multiply and start producing deadly toxins. Different kinds of clostridia also cause different diseases. Examples include tetanus, malignant edema, blackleg in cattle, enterotoxemia in young calves and foals, or life-threatening gut infection and diarrhea in young foals. Some types of intramuscular injections seem more risky for clostridial infections, especially flunixin meglumine (Banamine and its generic equivalents), if given in the muscle rather than in the vein. There is some thought that this drug sets up an ideal pH in the tissues for these bacteria to grow (basic, as opposed to acidic). A clostridial infection can happen with any kind of injection, but flunixin has been the most common culprit. Dr. Ray Randall, a semi-retired veterinarian in Bridger, Montana, says any time you give an injection, be aware of the possibility of adverse reaction. "This can occur with vaccinations, injections of vitamin E and selenium, etc. Banamine is the one we are most aware of (since it seems to be most often associated with reactions), and it doesn't matter how well you give the injection; there is always a risk. Clostridial bacteria are present in the environment and may even already be in the horse's body in spore form, just waiting for something to set up the right environment (such as damaged tissue from the injection)," he says. Irritation from the drug can cause part of that muscle to die. Normally this is not a big deal, but it can set up an anaerobic environment, which enables clostridia to thrive. It's not the bacteria themselves that cause the problem; it's the toxin that they secrete. When they multiply they produce toxins that damage the surrounding tissue even more, and produce gas. You can feel air bubbles under the skin--crinkly like bubble wrap. "I have some slides taken many years ago of a horse that I treated (in 1989) for a clostridial infection following vaccination. He survived and lived about 15 more years. He was disfigured from the infection, but still functional, and was used as a lesson horse for a long time," says Randall. "With Banamine or any of the generic flunixin products, the only way to minimize the risk is to give it orally or IV, and never in the muscle. It does have an intramuscular label on the bottle [stating that it can be given either IV or IM] though there is also a warning about possible adverse reactions when given IM, which include clostridial infection." This drug is safest to give orally but works fastest if given IV. "When people are giving injections of any kind, the number one thing is to be clean. Don't inject into a dirty area on the neck or buttocks. We used to use alcohol and it really doesn't do much good (it's not a very good disinfectant) but it does at least make someone think about where they are going to stick that needle, so it might help," he says. If you use alcohol, let the area dry again before injecting; a needle going through wet skin and hair is more likely to take dirt/bacteria with it. "Use a sterile needle, a new syringe and choose a clean spot on the horse. That's about all you can do to try to prevent problems. If you notice swelling later or the horse is not doing as well you'd expect, get veterinary help—the sooner the better. Load that horse in a trailer and take him to the vet, rather than calling and waiting for the vet to come to you. If you can get that horse in a trailer and get him to a vet, this may be a lot faster," says Randall. "The horse I treated for clostridial myositis in 1989 received a vaccination. He was not very good about injections, and the owner gave it to him in the hindquarter (but not in the best location). This horse also had a history of reactions," he says. "It was on a Friday when the owner called me. The horse had received the Clostridial Myositis following injections, and precautions for Banamine injections

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