Unilateral thyroidectomy in 6 horses.
Authors: Elce Yvonne A, Ross Michael W, Davidson Elizabeth J, Tulleners Eric P
Journal: Veterinary surgery : VS
Summary
# Unilateral Thyroidectomy in Horses: Surgical Management of Thyroid Masses When horses present with rapidly enlarging unilateral thyroid masses causing clinical signs such as tracheal compression or exercise intolerance, surgical removal may be necessary to relieve airway obstruction and restore function. A retrospective review of six cases (aged 10–22 years) treated between 1985 and 2000 demonstrated that en bloc unilateral thyroidectomy successfully resolved clinical signs of compression, with masses ranging from 125 to 990 cm³ in volume and histologically identified as adenomas, carcinomas, or adenocarcinomas. The significant finding was that whilst tracheal compression improved post-operatively in all cases, three of the six horses (50%) developed ipsilateral laryngeal hemiplegia as a complication, attributable to recurrent laryngeal nerve injury during surgical dissection; notably, no tumour recurrence or metastatic disease occurred during 6–14 months of follow-up. For practitioners encountering thyroid enlargement, pre- and post-operative laryngoscopic examination is essential to detect nerve damage early, ultrasonography reliably identifies mass location and size to guide surgical planning, and meticulous intra-operative isolation and visualisation of the recurrent laryngeal nerve is critical to minimising this serious complication. The risk-benefit analysis must weigh relief of airway obstruction against the substantial risk of permanent laryngeal dysfunction affecting future athletic performance.
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Practical Takeaways
- •Thyroidectomy can effectively resolve clinical signs of tracheal compression from thyroid masses, but recurrent laryngeal nerve injury is a significant risk—obtain pre- and post-operative laryngoscopic examinations to document this complication
- •Careful surgical dissection and isolation of the recurrent laryngeal nerve is essential to minimize laryngeal hemiplegia risk; consider this outcome when discussing surgery with owners
- •Use ultrasound to localize and measure thyroid masses for surgical planning, but do not rely on imaging to determine tumor type—histopathology will be needed post-operatively
Key Findings
- •Unilateral thyroidectomy successfully resolved tracheal compression in all 3 affected horses
- •Ipsilateral laryngeal hemiplegia occurred in 50% (3/6) of horses post-operatively despite surgery resolving primary compression
- •No tumor recurrence or metastatic disease occurred in 6-14 months follow-up
- •Ultrasonography useful for detecting thyroid enlargement but cannot reliably characterize tumor type