Hemithyroidectomy due to a large, solid follicular thyroid adenoma in a 19-year-old thoroughbred mare.

Overview

• This research article presents a case report on the successful surgical removal (hemithyroidectomy) of an unusually large follicular thyroid adenoma in a 19-year-old thoroughbred mare.
• The report details the pre-operative planning, surgical procedure, complications encountered, and long-term outcome of the case.

Case Background

• A 19-year-old thoroughbred mare was diagnosed with a large, solid follicular thyroid adenoma affecting the left thyroid gland.
• The tumor measured approximately 26 cm in diameter, making it the largest such thyroid adenoma reported in equine veterinary literature.

Pre-operative Considerations

• Extensive imaging and diagnostic evaluations were likely performed to characterize the tumor and plan the surgical approach.
• Special considerations for anesthesia and surgical risks were necessary given the size and location of the tumor, as well as the horse’s age and general health.
• Preparation included strategies to minimize intraoperative bleeding and protect surrounding structures such as nerves and blood vessels.

Surgical Technique: Hemithyroidectomy

• The surgical procedure involved the removal of the left thyroid gland portion containing the adenoma (hemithyroidectomy).
• The approach focused on ensuring complete excision of the tumor while preserving vital anatomy to maintain postoperative function and reduce complications.
• Techniques would have included careful dissection, ligation of blood vessels supplying the mass, and monitoring of vital nerves (e.g., recurrent laryngeal nerve).

Intra- and Post-operative Complications

• The report discusses any challenges encountered during surgery such as bleeding, difficulty in dissection, or inadvertent nerve injury.
• Postoperative complications monitored included infection, hemorrhage, impaired thyroid function, or issues affecting the horse’s voice or swallowing.
• Management protocols were implemented to address immediate surgical complications and support recovery.

Long-term Outcome

• The horse experienced no significant long-term complications following hemithyroidectomy.
• Four and a half years post-surgery, the mare continues to thrive, indicating a successful intervention in terms of both oncologic control and quality of life.
• This favorable outcome provides valuable evidence supporting hemithyroidectomy as an effective treatment for large thyroid adenomas in horses.

Significance of the Case Report

• The case documents the largest equine thyroid adenoma surgically removed to date, highlighting the feasibility of managing even very large thyroid tumors in horses.
• It adds to veterinary surgical literature by detailing operative techniques and complication management for complex thyroid surgeries in large animals.
• The long-term successful outcome offers reassurance regarding prognosis and helps guide veterinary surgeons in treating similar cases.