Stars in your eyes are one thing, but "cherries" in your dog's eyes signal trouble. Clinically known as nictitans gland prolapse, cherry eye leaves a mass of red tissue visible in the inside corner of the dog's eye. The condition occurs when the dog's third eyelid pops out or otherwise becomes dislodged from its normal position.
Like cats, dogs have three eyelids - an upper, a lower and a third, largely invisible, eyelid which contains a tear gland and acts as a windshield wiper across the eye. It's when this third eyelid comes loose from its normal position (prolapses) and swells that the animal is diagnosed with cherry eye.
It's not yet understood exactly why this gland tends to prolapse, but the problem is passed down from generation to generation and usually appears before the dog is one year of age. The leading theory is that the affected dog has a weakness in the connective tissue that attaches the tear gland to the surrounding structures in the eye. It's also speculated that the condition may result from eye inflammation caused by dermatitis, metabolic and/or immune system problems, cancer, trauma, sun damage and bacterial, parasitic and fungal infections.
Once the gland pops out of position and is exposed to dry air, irritants and bacteria, it can swell and become infected, often producing a mucus discharge. When this occurs, most dogs will rub or scratch at the affected eye, further irritating the problem and possibly creating lesions on the surface of the eye. The end result is the red, swollen appearance that gives the disorder its name.
Cherry eye is treatable, and the treatment consists of a surgical procedure to reposition the prolapsed gland. The surgery should be performed as soon as possible after diagnosis, in order to reduce the risk of additional infection and trauma to the eye. Also, the gland should be surgically put back into position, not removed entirely. Formerly this condition was treated by surgical removal of the gland, which interfered with the dog's ability to produce tears. Later on in life dogs whose third eyelid had been removed were subject to a form of conjunctivitis, also known as "dry eye." Dry eye is a serious condition and one that often can cause a dog to go blind or lose a significant amount of vision. Most animals are prescribed a topical antibiotic ointment to be used on the eye for several days to a week post surgery.
Cherry eye can occur in any breed of dog, and it affects males and females equally. A few breeds are more susceptible to developing the condition, including Beagles, Bloodhounds, Boston Terriers, Boxers, Bulldogs, Bull Terriers, Lhasa Apsos, Neapolitan Mastiffs, Saint Bernards and Shar-Peis.