Partial parotid sialoadenectomy in a horse with parotid ductal carcinoma: Surgical description and case report.

This research paper presents the surgical approach and long-term results of a case where a horse was treated for parotid salivary gland cancer through partial removal of the gland.

Surgical Findings and Procedure

• The 12 year old American Quarter Horse gelding was observed to have a 10×10 cm swelling below the base of the right ear.
• A sonogram examination disclosed a formation involving the right parotid salivary gland.
• An incisional biopsy was executed, which confirmed the diagnosis of parotid carcinoma.
• The tumor was subsequently marginally removed.
• The lateral wall of the guttural pouch, a notable structure in horses linked to the middle ear, was also excised along with the mass.
• The removed part was then reconstructed with a porcine small intestinal submucosal (SIS) sheet, a type of biological tissue often used in surgical treatments for its regenerative properties.
• To discourage the growth of remaining cancer cells, Cisplatin beads, a form of chemotherapy, were implanted into the wound bed prior to final closure of the surgical site.
• Post surgery, the horse was placed on a daily oral treatment of Firocoxib, an anti-inflammatory medication typically given to horses.

Postoperative Complications

• The gelding developed right-sided facial nerve paralysis post surgery. This is a known risk as the facial nerve passes closely to the parotid gland.
• A condition called dysphasia was noted, which meant the horse had difficulty swallowing fibrous feed.
• There was also surgical site dehiscence, a situation where a surgical wound reopens before it has adequately healed.
• However, the wound finally healed by the method called ‘second intention’, a natural process in which a wound heals by granulation tissue formation, contraction, and epithelialization without surgical closure.
• In the 6 months’ post-operative timeframe, there was a partial improvement in the facial nerve functionality.

Long Term Result

• By the 12 month mark, there was no sign of recurring or metastatic tumor.
• The gelding was also able to return to work, demonstrating a successful outcome to the surgery and recovery process.

Conclusion

• The paper concludes with the assertion that partial parotid sialoadenectomy (removal of part of the parotid gland) showed a promising long-term outcome for the horse.
• The importance of regional anatomic knowledge, understanding the structure and function of particular body areas, is highlighted as crucial in achieving such results.