Successful surgical removal of a pheochromocytoma in a mare via trans-costal approach.
Authors: O'Brien Thomas J, Pezzanite Lynn M, Acutt Elizabeth V, Vilander Allison C, Hassel Diana M, Hector Rachel C, Hendrickson Dean A
Journal: Equine veterinary journal
Summary
# Pheochromocytoma Removal in the Horse: A Surgical Milestone Pheochromocytomas—catecholamine-secreting tumours of the adrenal medulla—have been documented in equine case reports, yet successful ante-mortem diagnosis and surgical removal without recurrence remained unprecedented until this 2023 report. An 18-year-old Quarter Horse mare presenting with a two-month history of recurrent colic, profuse sweating, muscle fasciculations and behavioural agitation underwent comprehensive diagnostic imaging (transcutaneous and transrectal ultrasonography) that identified a unilateral left adrenal mass, confirmed histopathologically as pheochromocytoma via positive immunohistochemical staining for synaptophysin and chromogranin A. The surgical team achieved excellent mass visualisation using a trans-costal approach with 18th rib removal and left kidney retraction, successfully ligating associated vasculature within 86 minutes of operative time, though intra-operative hypertension and tachycardia and post-operative complications including pelvic flexure impaction and nasogastric reflux required management. The mare recovered soundly and returned to ridden work at six months post-operatively with no recurrence of clinical signs—a significant outcome that demonstrates adrenal tumour surgery, whilst challenging, is achievable in horses with appropriate diagnostic rigour, surgical expertise and perioperative care. For practitioners, this case underscores the importance of considering neuroendocrine tumours in horses presenting with recurrent colic and autonomic dysfunction, particularly where imaging reveals adrenal abnormalities, and highlights that surgical intervention can offer curative potential rather than a purely palliative approach.
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Practical Takeaways
- •Pheochromocytomas can be successfully diagnosed and surgically removed in horses; consider this diagnosis in mares presenting with recurrent colic, profuse sweating, and agitation over extended periods.
- •The trans-costal approach with 18th rib removal provides excellent visualization for adrenal mass removal and vessel ligation, resulting in successful outcomes despite potential intraoperative and postoperative complications.
- •Horses can return to athletic use following surgical adrenal mass removal when complications are managed appropriately, offering a realistic prognosis for owners of affected animals.
Key Findings
- •An 18-year-old Quarter Horse mare with a left-sided adrenal pheochromocytoma was successfully diagnosed antemortem and surgically removed via trans-costal approach with 18th rib removal.
- •Surgical and anesthesia times were 86 and 114 minutes respectively, with successful management of intraoperative hypertension/tachycardia and postoperative colic complications.
- •Immunohistochemistry confirmed pheochromocytoma diagnosis through positive labeling for synaptophysin and chromogranin A.
- •The mare recovered well at 6-week recheck, returned to training at 6 months postoperatively, with no recurrence of clinical signs or tumor-related symptoms.