Equine lymphangitis is an inflammation or swelling associated with impairment of the lymphatic system, particularly in a limb, in horses. It is most commonly a bacterial infection, although bacterial culture may be negative.
Often referred to as fat- or big-leg disease, it is sometimes known as weed or Monday-morning disease (not to be confused with the more common usage of MMD referring to exertional rhabdomyolysis or azoturia). This article refers mainly to sporadic lymphangitis. Ulcerative lymphangitis is referred to in passing, as it is managed in a similar manner. Epizootic lymphangitis is similar to glanders, but caused by the fungus Histoplasma farciminosum.[1]