As you stare into your dog’s eyes, you may have noticed that they actually have three eyelids, not just two like humans do! Dogs have an upper and lower eyelid similar to people, and then one that is positioned at the inside corner of the eye that slides under the other two lids. It’s a great design to keep the eye protected and this third eyelid is crucial for producing tears.
What is Cherry Eye in Dogs?
Occasionally, the gland located in this third eyelid can prolapse, or become everted causing a ‘cherry eye’. This looks like a fleshy pink protrusion at the corner of the eye and is not painful. Many times the dog isn’t bothered by it at all, although infection or conjunctivitis can accompany a cherry eye. As the prolapsed gland becomes irritated, it can swell and become quite irritated and large.
What is the Third Eyelid and Why is it I Important?
The tear film has three portions, the aqueous/ liquid portion, an oil, and a mucoid portion.
The oil portion comes from the glands of the upper and lower lids. The mucoid portion comes from the conjunctiva (the white part around the eye). The tear portion comes from two lacrimal glands, one above the eye and the other located in the third eyelid.
When the third eyelid is prolapsed or damaged, the eye becomes at an increased risk for not being able to produce enough tears, causing a dry eye. Left untreated, about 40% of eyes with a cherry eye will subsequently lose the ability to produce tears from that gland, leading to a dry eye2. A dry eye is uncomfortable and can be prone to infections and corneal damage.
In addition to producing a portion of the tear film, the third eyelid also protects the globe from trauma and irritants.
What Causes a Prolapsed Third Eyelid or Cherry Eye?
The underlying cause for a Cherry Eye is unknown. A hereditary component has been documented and there are many breeds that are overrepresented with regards to the diagnosis of cherry eye.
Affected Breeds
Cherry eye is most common in the following breeds:
Cherry eye has been diagnosed in some cat breeds, but it is very uncommon.
The majority of prolapsed third eyelids are diagnosed in young dogs less than 2 years of age, although the onset can vary4.
About 40% of dogs that have a cherry eye in one eye will go on to prolapse the other gland as well1. In most cases this happens within 3 months of the first prolapse.
Treatments for Cherry Eye in Dogs
The diagnosis of a cherry eye needs to be made by a veterinary professional. In general, the diagnosis is made based on the appearance of the pink fleshy mass at the inside corner of the eye. Your vet will probably do some tests on the eye, including tear testing, and staining to ensure there are no other problems. Unfortunately, there are no known preventative measures for cherry eye only to treat it either medically or surgically, so no further infections occur.
Medical Treatments for Cherry Eye
Often an attempt to manage the prolapsed third eye medically is made initially prior to any surgical attempts. This is generally unsuccessful, but topical steroids can be used to reduce swelling and inflammation. This, in turn causes the gland to shrink, and in mild or intermittent cases, some can resolve.
Surgical Treatments for Cherry Eye
In general, surgery is indicated to replace the gland in its original position. A gland left prolapsed is more prone to losing the ability to produce tears and develop a dry eye.
An older surgical method included excising and removing the gland altogether. While cosmetically this looks good, about 50% of eyes treated this way develop dry eye, versus 14% in those that are surgically replaced1.
Recovery time is generally quick. Most pets are sent home with eye drops and oral pain medication, as well as an Elizabethan collar (cone of shame). There is a possibility of re-prolapse, and statistics vary depending on the surgical technique used and the skill level of the surgeon, but are thought to be less than 25%3.
Considering Pet Insurance while your pet is young, especially in breeds predisposed to hereditary problems such as cherry eye, is always a good idea to help defray the cost of veterinary care.
1Mazzucchelli, S., Vaillant, M. D., Wéverberg, F., Arnold‐Tavernier, H., Honegger, N., Payen, G., ... & Chahory, S. (2012). Retrospective study of 155 cases of prolapse of the nictitating membrane gland in dogs. Veterinary Record, 170(17), 443-443.
2Morgan, R. V., Duddy, J. M., & McClurg, K. (1993). Prolapse of the gland of the third eyelid in dogs: a retrospective study of 89 cases (1980 to 1990). The Journal of the American Animal Hospital Association (USA).
3Multari, D., Perazzi, A., Contiero, B., De Mattia, G., & Iacopetti, I. (2016). Pocket technique or pocket technique combined with modified orbital rim anchorage for the replacement of a prolapsed gland of the third eyelid in dogs: 353 dogs. Veterinary ophthalmology, 19(3), 214-219.
4Plummer, C. E., Källberg, M. E., Gelatt, K. N., Gelatt, J. P., Barrie, K. P., & Brooks, D. E. (2008). Intranictitans tacking for replacement of prolapsed gland of the third eyelid in dogs. Veterinary Ophthalmology, 11(4), 228-233.