History
6 year old Thoroughbred gelding, presenting a swelling with purulent discharge in the region of the withers. No improvement was reported after antibiotic and anti-inflammatory treatment and the horse was unable to be ridden.
The referring veterinarian made a radiographic examination that showed some remodeling and new bone formation on the spinous processes of the withers probably following a severe trauma or even a fracture. The horse was referred for the treatment of the fistula and debridement of the spinous processes if needed.
Clinical and radiographic examination and surgery
The horse showed good bodily condition and in the region of the withers a painful and hot swelling was present, with purulent discharge from a fistula. The radiographic examination confirmed the bone remodeling of the spinous processes of the withers. With the horse under general anesthesia, a probe was inserted in the fistula to better understand which spinous process needed to be curetted. The direction of the probe as seen radiographically ruled out any involvement of the spinous processes in this case of septic bursitis localized under the nuchal ligament at the level of spinous processed T3-T5 (Fig. 1).
Fig.1
The affected bursa was open and deeply debrided with removal of all necrotic and purulent tissue. Attention was paid to remove the whole synovial tissue. When sutured, the bursa was left partially open in its caudal limit to allow drainage and a stent bandage was sutured over the incision line to protect from contamination. The stent was removed 5 days later, just before dismission, when the horse showed some swelling in the area but without any discharge.
Follow up
After 4 months, the swelling in the area of the withers was absent and the incision line perfectly healed. The horse resumed regular work and was ridden without problems.
The supraspinous bursa is a synovial cavity interposed between the nuchal ligament and the spinous processes of the withers to smooth the friction between the two structures. It is normally a virtual cavity, not visible or palpable unless it becomes inflamed or infected, like in the present case. The antibiotic treatment alone is rarely resolutive. The surgical curettage or the radical removal of the whole synovial tissue of the bursa are frequently needed to get a complete resolution.