Retrospective Evaluation of Hemithyroidectomy in 14 Horses.
Authors: Troillet Antonia, Böttcher Denny, Brehm Walter, Scharner Doreen
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Hemithyroidectomy for Equine Thyroid Neoplasia Unilateral thyroid masses in horses present a diagnostic challenge, as clinical presentation alone cannot distinguish benign from malignant disease; this retrospective review of 14 horses (aged 6–21 years) undergoing hemithyroidectomy between 2003–2015 clarifies outcomes and complication rates for this surgical intervention. Adenocarcinomas comprised the majority of tumours (11/14), with mares more commonly affected, and all cases were confirmed histologically following complete surgical resection of the affected lobe. The modified hemithyroidectomy technique proved remarkably safe: whilst seroma formation occurred in four cases postoperatively, no horses experienced laryngeal hemiplegia—a significant finding given the anatomical proximity of the recurrent laryngeal nerve—and no evidence of metastatic disease or thyroid dysfunction emerged during mean follow-up of 4.9 years. These results support complete surgical excision as an effective curative approach with excellent long-term prognosis, provided preoperative assessment includes ultrasound imaging and upper airway endoscopy to characterise the mass and rule out laryngeal involvement. For equine practitioners, this work demonstrates that thyroid neoplasia, whilst uncommon, warrants definitive surgical management rather than conservative monitoring, with appropriately executed hemithyroidectomy offering predictable outcomes and owner satisfaction.
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Practical Takeaways
- •Thyroid neoplasia in horses can be successfully managed with hemithyroidectomy, with low complication rates and excellent long-term outcomes when using modified surgical technique
- •The modified hemithyroidectomy preserves recurrent laryngeal nerve function, eliminating laryngeal hemiplegia risk—a critical advantage over alternative approaches
- •Complete surgical resection appears curative for thyroid neoplasia in horses with no recurrence or systemic spread documented over multi-year follow-up periods
Key Findings
- •11 of 14 thyroid tumors were adenocarcinomas, predominantly affecting mares (9/14)
- •No horses developed postoperative laryngeal hemiplegia following hemithyroidectomy using modified surgical technique
- •No clinical signs of metastases or thyroid dysfunction observed at mean follow-up of 4.9 years in any horse
- •Complete surgical resection prevented local recurrence of neoplastic thyroid tissue with 100% owner-reported successful long-term outcome