the shape of their face and having a short nose.
Normally the gland of the third eyelid (nictitans gland) is located behind the third eyelid in the inner corner of the eye. This gland is attached to the fascial covering of the eye and eye socket by a fibrous band of tissue. Structural weakness of this attachment can lead to prolapse of the gland. The result is "cherry eye," so called because the prolapsed gland is exposed on the surface of the eye and becomes red, inflamed and swollen.
Some breeds of dogs are predisposed to have prolapse of the nictitans gland. These include cocker spaniels, bulldogs, beagles, bloodhounds, Lhasa apsos, and Shih tzus. Typically, affected dogs are between six months to two years of age when this occurs.
The gland is an important lacrimal, or tear-producing gland, and so it should not be removed. In the past cherry eye was treated with surgical excision of the gland; subsequently veterinarians found that this frequently resulted in keratoconjunctivitis sicca, or "dry eye." Currently, recommended treatment involves surgically returning the gland to its proper position. Topical medications may help diminish inflammation and swelling, provide moisture, and fight associated infection before surgery, but are not recommended for long-term treatment.
Surgical repositioning of the gland is commonly performed for cherry eye. Typically dogs do well after this surgery, but in five to 20 percent of these cases the gland can re-prolapse. Additionally, it is common for cherry eye to occur in the opposite eye as well. It is not recommended breeding a cocker with cherry eye or it will be passed down to the offspring.