Twice, my 12-year-old Paint gelding has gotten his third eyelid "stuck" over the top of his eyeball for 10 or 20 seconds. The first time was when water splashed in his eye during a bath. He tossed his head, rolled his eye upward, and the third eyelid stuck over the top of his eyeball, blocking his vision. Today the same thing happened when he rubbed his eye on his knee. He wasn't alarmed and continued eating his hay. I ran to retrieve saline solution. By the time I returned, his eyelid was normal.

This gelding is heterozygous for HYPP, although his HYPP is easy to manage with consistent exercise, a regular feeding schedule, daily turnout, and ample clean water. Over the years I have noticed that the beginning of an HYPP attack corresponds with the third eyelids being unusually high, covering the corners of his eyes. In contrast, these two "stuck" incidents affected only the right eye and seemed to be unrelated to any HYPP symptoms.

Why does his third eyelid get stuck over his eye? Would saline have helped the third eyelid return to normal?

The third eyelid (nictitating membrane) flips up and rarely gets "stuck," so this behavior suggests a brief, purposeful, spastic episode or pain. In disorders where the eyelid acts "spastic" and stays up, both eyes are usually affected, as can happen with HYPP episodes, tetanus, metabolic imbalances such as hypocalcemic tetany, and neurologic toxicities