The picture above is that of a horse that was treated by its owner with 10cc of Banamine (Flunixin Meglumine) in the muscle (IM) of the left hind leg for colic symptoms. The good news was that the horse's symptoms of colic resolved however 2 days later the injection site was swollen and painful to the touch. The following day, the horse was febrile and lame at the walk. The wound was examined via ultra-sound and a large, fluid filled pocket was noted deep to the swelling. The pocket was drained of purulent (pus) fluid and the horse was started on antibiotics. Fortunately, the horse recovered fully with only a minor scar.
This type of reaction may occur secondary to any intra-muscular injection. However, the big concern with injection site abscesses caused by IM Banamine is the association with the bacteria Clostridium and the resulting Clostridial myositis. These bacteria are anaerobic and thrive in low oxygen environment, hence treatment involves aggressive surgical exposure and drainage of the contaminated tissue. Severe Clostridial myositis can readily result in death of the horse!!
The preferred route of administration for Banamine is either intra-venous or by mouth.