Equine Supraspinous Bursitis / Fistulous Withers – NAVLE Study Guide

Overview and Clinical Importance

Supraspinous bursitis, commonly known as fistulous withers, is a chronic inflammatory and often septic condition affecting the supraspinous bursa located at the withers of horses. This condition represents a clinically significant problem in equine practice, particularly in developing nations where horses serve as working animals. The condition is characterized by painful swelling, formation of draining fistulous tracts, and potential involvement of underlying bone structures.

The clinical importance of fistulous withers extends beyond the individual horse due to its strong association with Brucella abortus infection, a significant zoonotic pathogen. Veterinarians must exercise appropriate biosecurity measures when handling suspected cases to protect themselves and other personnel from potential infection.

Anatomy of the Withers Region

The withers represents the highest point of the horse's back, formed by the elongated dorsal spinous processes of the cranial thoracic vertebrae (T2-T12). These processes are angled caudally and can extend up to 7 inches in length, providing critical attachment points for the major ligaments supporting the neck and back.