Clostridial Myositis, or Banamine Injections Gone Wrong

I opened an email the other day from my brother, at my own peril. I knew from its title, clostridial myositis, that is probably wasn’t a cute picture of my nephew out playing in the mud. This is what I found:

Hmmm…this isn’t good. Not good at all.

When I called Matt up and asked him what had happened, he said that a client thought her horse was acting a bit colicky, so she had given a Banamine injection into her neck muscle. The next day, she noticed that the horse’s neck began to swell and that she was moving a bit stiffly. She kept an eye on the horse for two days, but when the horse didn’t improve, she called in Matt. When Matt examined the horse, he noted that when the muscle was palpated, it made crackling sounds, much like tiny bubbles being popped or that sound you hear when you first pour milk over your Rice Krispies. He flipped up the horse’s top lip and saw that its gums were red up to the point of the teeth, but at the teeth, there was a bluish-purple line, which veterinarians refer to as a toxic line. He diagnosed that a bacterial infection, clostridial myositis, had taken hold.

To treat the infection, Matt had to take drastic action by cutting into the affected muscle. Because clostridial myositis is an anaerobic infection–remember that crackling sound when it was palpated–its exposure to air helped to release bacteria and necrotic debris and to establish drainage. Without this exposure, abscesses would begin to form within the muscle. He and then later the owner continued to treat the horse using high doses of IV potassium penicillin, metronidazole, and anti-inflammatory agents. (IV fluids would normally be given as well, but the horse’s neck was so swollen that he couldn’t find a vein.) And if this weren’t enough, Matt thought it likely that the horse would continue to slough skin and muscle at the affected area, if it managed to pull through. There was still the very real chance that the infection was so far gone that the horse could die.

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Wound Debridement to Treat Clostridial Myositis

Banamine is clearly labeled as being given either intravenously (directly into a vein) or intramuscular (directly into the muscle). The Clostridium bacteria, the guilty party in this scenario as well as in tetanus and botulism, is likely present on or in the skin or even possibly in the muscle itself. When Banamine is given as an intramuscular injection, that bacteria is then pushed into the horse’s muscle along with the Banamine. The bacteria then sporulated (the technical term for producing spores), causing the muscle to swell at the injection site. If conditions are necrotic, the spores convert to their vegetative form and release powerful exotoxins. Within 48 hours, the horse will become depressed, exhibiting fever, blood poisoning, rapid breathing. The injection site will swell and exhibit crepitus, that crackling sound mentioned earlier. If the infection continues without treatment, the horse will exhibit tremors and the lose control of its muscles, fall into a coma, and possibly die.

So, why did this happen? For the record, this is not necessarily a question of site cleanliness or the owner administering a medication incorrectly. This type of infection can happen with any intramuscular injection, although it does seem to happen with Banamine more often than anything. Matt, or Dr. Randall the younger, has personally seen it happen with generic Adequan and he’s heard of it happening with penicillin. Dad, or Doc Randall, has seen two reactions that were secondary to vaccinations, one after an injection of Vitamin E and Selenium, and a few from intramuscular Banamine injections. It can also happen if needles are reused, a strict no-no if there ever was one. Additionally, not all horse owners are comfortable hitting a vein on their horses to deliver a Banamine injection intravenously. For those that are not–and it is perfectly acceptable to not be–most veterinarians will recommend using 15-20% more Banamine and shooting it into the horse’s mouth. The horse won’t absorb all of the medication, hence the need to use a bit more. This is an extra- or off-label use of the medication, but it will be just as effective.

I could not help but feel for both the horse and the woman who owned the horse. She hadn’t done anything wrong. She followed the instructions on the label and treated her horse accordingly. Unfortunately, she just happened to have that unlucky 1-in-1000 horse where this reaction took hold. In cases like this, it is perfectly natural, though unwarranted, for an owner to feel guilty. It is important, however, to not let guilt or fear of being incorrect get in the way of contacting your veterinarian immediately. Your horse’s odds of survival increase the earlier that treatments begins. This story does have a happy ending, however, in that this particular horse recovered. Her name is Ellie. She did lose some skin and muscle, but she lived to tell the tale.

Author’s note: Banamine is the common name for Flunixin, a widely used non-steroidal anti-inflammatory drug, and Banamine is how it will most commonly be referred to by veterinarians. It is worth knowing some of its other common names as well. In the USA, its trade names are BanamineFlunixamineCitationEquileve, and Meflosyl Solution. In the United Kingdom and European Union, the trade names are FlunixinFinadyne, and Cronyxin. In South Africa and Australia, a common trade name is Finadyne. In India, it is Megludyne. Banamine, regardless of what name it goes by, is an incredibly potent drug and should be used only after consultation with your veterinarian. It is very dangerous for use in dehydrated horses. It is worth noting that while Banamine is a very useful drug, it can also cover up a lot of symptoms, thereby making it more difficult for a veterinarian to diagnose what is actually wrong with your horse.

The photos below were taken by Ellie’s owner. While not for the faint of heart, they do an excellent job of capturing the day-by-day treatment of this particular case.

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