Answer: Upon physical exam, the left neck was found to be swollen and very painful. After clipping and an ultrasound of the neck, gas pockets were seen within the muscle layers. The diagnosis of Clostridial Myositis (Gas Gangrene) was made. Large incisions were made in the neck to bring oxygen to the anaerobic infection and create drainage. IV fluids, anti-inflammatories and antibiotics were started immediately. This is a gangrenous infection of the muscle due to the Flunixin injection (by the care giver) being given in the muscle. This infection progresses quickly with swellings filled with gas and if not treated aggressively it can be fatal. Even though the product is labeled for IM use, NEVER EVER give it this way to a horse! View the pictures below!