Mast cell tumor invading the cornea in a horse.

The research outlines a successful treatment of a horse with a mass tumor in its eye. The tumor was identified as a densely packed growth of abnormal cells, was surgically removed, and showed no sign of recurrence over two and a half years after the procedure.

Tumor Identification

• A three-year-old horse was presented with visible symptoms of a tumor growing in its right eye.
• The tumor appeared as a red mass emerging from behind the eyelid and seemed to originate in the bordering area between the cornea and the white of the eye, spreading extensively into the cornea.
• At the time of presentation, no other abnormalities, either in the eyes or throughout the horse’s system, were detectable.

Tumor Treatment

• The tumor was surgically removed via a procedure known as a lamellar keratectomy. This operation involves peeling away the affected layers of the cornea to excise the tumor.
• A laser therapy was also used in the surgery to treat the exposed area left by the removal of the tumor, as well as its surrounding areas.

Post-surgery Observations

• The removed tumor tissue was examined under a microscope (histopathological evaluation), and results showed it was made up of densely packed abnormal cells (mast cells), separated by fibrous tissue.
• The preparations were stained to detect Ki67, a protein in the cell nucleus often used as a marker for proliferation. On average, 370 of the 1000 counted cells were positive for Ki67, suggesting a high rate of division among mast cells.
• Two months after surgery, the wound had healed with no excessive capillary growth on the cornea surface. The cornea was clear, with no visible superficial vascularization around the scar.
• For this particular case, there was no recurrence of the tumor 32 months (almost 3 years) post-treatment