Banamine (flunixin meglumine) is a non-steroidal anti-inflammatory (NSAID) medication that is highly effective for the relief of pain, inflammation, and fever in horses. Many horse owners become familiar with Banamine when their horse has an episode of colic, as it is often one of the first treatments administered to improve comfort.
Banamine is available in both injectable and oral forms. Veterinarians typically administer the injectable form intravenously (IV) using a sterile needle and syringe. It is not uncommon for horse and barn owners to have either the injectable solution or oral paste on hand to provide pain relief when necessary, often while waiting for the veterinarian to arrive.
For years many horse owners, and even for some time veterinarians assumed the safety of Banamine to be given in the muscle. Injectable Banamine labels clearly state “For Intravenous or Intramuscular Use in Horses” after all. So what’s the big deal?
Product labeling is not a guarantee of safety and there can be very serious consequences to administering Banamine in the muscle. Banamine, along with a number of other drugs, including ivermectin and anti-histamines, have been associated with a very serious muscle disease, clostridial myonecrosis, also known as “gas gangrene”.
Clostridial myonecrosis is a life-threatening infection of muscle tissue caused mainly by the anaerobic bacteria Clostridium perfringens and several other clostridial species. These clostridial bacteria are present in the environment, but can also remain dormant in healthy muscle. These spores begin to proliferate when the muscle is damaged with an injection of certain drugs, including Banamine. The growth of these bacteria in the muscle leads to tissue damage, blood supply disruption, and toxin release.
Horses affected with clostridial myonecrosis may exhibit signs as early as hours following an injection. Others may not show anything until a few days later. The first signs seen are usually inappetance, fever, and painful swelling at the site of injection. Crepitus, an audible crackling indicating air beneath the skin, may also be present on palpation. Injection site swelling often progresses rapidly to sloughing of the skin and muscle as the toxic bacteria causes the tissues to die.
After initial clinical signs present, affected horses often deteriorate rapidly as the toxins from the bacteria are released into the bloodstream. Horses left untreated can die within 48 hours of initial clinical signs due to the toxins’ rapid effect on circulation and body organ function. Even those that receive aggressive therapy can progress to death due to significant compromise to the cardiovascular system.
Treatment must be early and aggressive, involving both surgical removal of the affected tissue and extensive supportive medical care. Horses that develop clostridial myonecrosis often require long and expensive hospital stays that include intravenous fluid therapy, anti-inflammatory and anti-microbial treatment, and extensive wound management. Even those receiving appropriate and rapid care face a 40% chance of death and those that survive will often require long term, high cost treatment.
In summary, prevention is much simpler than treatment! While clostridial myonecrosis is a rare complication of intramuscular Banamine use, the risk to your horse is simply not worth it. The injectable product can be effectively administered by mouth, reaching active concentrations in the blood within 15 minutes. As always, it is recommended to consult with your veterinarian prior to administering a medication such as Banamine so an appropriate dose and method of administration can be provided.
