What is Eyelid Protrusion (Cherry Eye) in Dogs?
Cherry eye is the common name for prolapsed gland of the third eyelid, meaning the gland has moved (prolapsed) out of its proper position. While humans only have two eyelids, dogs have three. Their third eyelid is located in the lower inner corner of the eye (close to the muzzle). This eyelid is made of conjunctiva (a thin, protective membrane), a T-shaped cartilage (firm connective tissue), and a lacrimal gland (tear gland). The tear gland is located at the bottom of the cartilage and cannot typically be seen.
In some dogs, the T-shaped cartilage flips upside-down, exposing (prolapsing) the third eyelid gland. When exposed, the gland often appears like a red or pink mass in the lower inside corner of the eye—this is where the term “cherry eye” comes from.
Certain dog breeds are more predisposed to cherry eye than others. Researchers aren’t sure exactly why, but there is likely a genetic component. It is suspected that the connective tissues that hold the gland in place are not as strong as they should be in these particular breeds.
Some of the most commonly affected breeds include:
Symptoms of Eyelid Protrusion (Cherry Eye) in Dogs
The hallmark sign of cherry eye is a round, red or pink mass in the lower inner corner of the eye that looks like a cherry pit. This disease can affect either one eye or both eyes.
Symptoms of cherry eye that may be noticed at home include:
It is important to note that prolapse of the third eyelid gland is not painful. However, cherry eye can lead to secondary issues, such as ulcers of the cornea (the eye’s clear, protective outer layer) and chronic dry eye (not enough tears), which can be uncomfortable.
What Causes Cherry Eye in Dogs?
Cherry eye doesnt always have a distinct cause. However, many veterinarians believe it is a genetic problem since some breeds are more likely to suffer from it than others. The breeds most likely to get cherry eye are: American cocker spaniels, Shih Tzus, beagles, Lhasa apsos, Pekingese, Maltese, basset hounds, rottweilers, Neapolitan mastiffs, Shar-Peis, Boston terriers, saint bernards, and English bulldogs.2
Other possible causes of cherry eye include:
Cherry eye is not the same as an eye infection. Infections typically need some type of irritant or foreign body. However, cherry eyes in dogs can happen out of nowhere. However, cherry eye can lead to infections. When your dogs third eyelid prolapses, it becomes more sensitive and is susceptible to foreign bodies that can cause infection, including dust in the air. Eye infections can also lead to cherry eye, as irritation from the infection can cause the third eyelid gland to become inflamed and prolapse.
Additionally, cherry eye is not the same as dog allergies. While allergies can cause irritation and dry eye, they do not cause this type of inflammation.
In general, the red, inflamed bump you see in your dogs eye is caused when the ligaments surrounding the third eyelid rupture. Any dog can have weak ligaments, and any dog born with weak ligaments will likely suffer from cherry eye.