Retrospective Evaluation of Hemithyroidectomy in 14 Horses.

This study looks into the results of hemithyroidectomy, a medical procedure undertaken on horses exhibiting histologically confirmed mismatched thyroid neoplasia. The treatment’s short and long-term effects are reviewed, specifically regarding potential complications such as laryngeal hemiplegia. The study concludes that surgical removal of the irregular lobe prevents local recurrence of cancerous thyroid tissue, without evident long-term clinical signs of metastases or a thyroid disorder.

Study Context and Methodology

• The research involves a review of medical records of 14 client-owned horses that presented unilateral thyroid mass due to neoplasia between 2003 and 2015, all of which underwent preoperative evaluations, including an ultrasound examination of the mass and upper airway endoscopy before the hemithyroidectomy.
• These horses ranged in age from 6-21 years, with the majority of tumors being adenocarcinomas and predominantly diagnosed in mares.
• A follow-up was done two weeks post-surgery, and long-term monitoring of the horses covered more than six months to observe the procedure’s success rate and potential complications.

Findings and Results

• In a small number of cases, intraoperative complications like hemorrhage were noticed, and postoperative complications including seroma formation were observed.
• Significantly, none of the horses developed postoperative laryngeal hemiplegia, a condition that can cause difficulties in swallowing and changes in voice, which had been a concern as a potential outcome of the procedure.
• The report states that during the follow-up period (averaging 4.9 years), no horses showed signs of metastases or developed any thyroid disorder, indicating no long-term ill effects from the procedure.

Conclusions and Implications

• The findings suggest that complete surgical resection of the abnormal thyroid lobe through hemithyroidectomy effectively prevents local recurrence of the neoplastic thyroid tissue.
• Owners of the treated horses reported a successful long-term outcome. This suggests that the procedure has a high success rate and results in positive health outcomes for the horses.
• According to the study, the observation of thyroid neoplasia in horses does not necessarily indicate malignancy, implying that these formations might not always be cancerous.