When the tear - producing gland of the third eyelid pops out of position, it protrudes from behind the third eyelid as a reddish mass at the inner corner of the eye. (northwestanimaleye.com)
The lacrimal gland of the third eyelid is held in place by tissue fibers but some individuals have weaker fibers than they should so the gland protrudes. (vin.com)
Cherry eye is known as a collapsed gland of the third eyelid. (dog-health-guide.org)