Primary lacrimal gland adenocarcinoma of the third eyelid in a horse.

This study showcases a rare case of lacrimal adenocarcinoma, a type of cancer, found in the third eyelid of a 5-year-old horse. The successful surgical removal of this mass and the animal’s subsequent free-from-disease status highlights the viability of surgical intervention in similar cases.

Case Overview

• The 5-year-old Draft Horse gelding was brought in for examination due to a large, fleshy, and ulcerated mass on its third eyelid, which had been present for 3 weeks.
• The horse underwent a complete ophthalmic examination as well as ocular ultrasound and skull radiographs to determine the extent and nature of the mass.

Findings

• The tests revealed a large soft tissue mass encompassing the entire third eyelid and extending into the right orbit to the level of the globe equator.
• No other physical or ophthalmic abnormalities were found in the examination, indicating that the problem was localized to the eyelid area.

Surgical Intervention and Results

• The mass was surgically removed via a procedure known as exenteration, 3 months after initial presentation.
• Post-surgical histopathology (microscopic examination of the removed tissues) led to the diagnosis of the mass as a lacrimal adenocarcinoma, a type of cancer, specifically located in the third eyelid.
• Another discovery during histopathology was the presence of Demodex caballi, a type of parasite, in the horse’s eyelid sebaceous glands. However, these were asymptomatic and likely simply incidental findings.
• No recurrence of the tumor or metastasis (spread of cancer to other parts of the body.) was noted 12 months after the surgical removal of the mass.

Significance of the Study

• This case represents the first reported incidence of a primary lacrimal adenocarcinoma in a horse – it highlights a rare occurrence in veterinary science.
• The successful surgical removal of the cancerous mass, as well as the horse’s disease-free status a year post-operation, demonstrates the effectiveness of the surgical treatment in such cases.