(EXCESSIVE TEAR PRODUCTION IN DOGS AND CATS)
IRRITATION TO THE EYE
One of the eye’s natural responses to irritation is to produce more tears. This helps flush away any irritants that might have contaminated the eye surface. If excessive tearing is accompanied by squinting or pawing of the eye, or if the excessive tearing should occur suddenly this should be taken as an obvious sign of eye pain and veterinary attention should be sought at once. Any accompanying loss of vision should be taken as an emergency.
It is the more chronic cases that are harder to manage. Eyes can certainly become chronically irritated from viral conjunctivitis (probably the most common reason for excessive tearing in cats), from glaucoma (painful increase in eye pressure in the eye), from reaction to certain eye medications, or more commonly from eyelash or eyelid abnormalities.
Some breeds of dogs naturally have hair in their eyes and this does not cause irritation in most cases but in some cases it can. Hairs can grow from the face at an angle so that they rub against the eye. Eyelashes can also grow at abnormal angles and rub on the eye. Eyelashes can even grow on the inner surface of the eyelids or corner of the eye and cause irritation. Often magnifying instruments are needed to discover these tiny hairs and delicate surgical procedures are needed to address them. Complicating the situation, however, is the fact that breeds that tend to have eyelid and eyelash problems also tend to be the same as those with faulty tear drainage anatomy (see below) which makes it very hard to determine which of many possible causes is to blame.
Allergy, irritating dust or smog in the air, trauma, or infection can lead to excessive tears from conjunctivitis. These problems can often be treated medically by a general practitioner. For further reading we recommend these links to other pages in our library:
NORMAL TEAR DRAINAGE
(original graphic by marvistavet.com)
Once we are certain that a painful condition is not present, we can consider that the drainage ducts of the eyes may not be normal. The normal eye is most efficient at draining tears. Looking at the inner corner of the eyelids (the side nearest the nose) one can see the pink, moist caruncle and on the eyelid margins upper and lower openings called nasolacrimal punctae. These are essentially drainage holes for tears. The punctae are the openings to small passages called canaliculi which, in turn, open into a sac called the lacrimal sac. The lacrimal sac drains into the nasolacrimal duct which drains tears into the nasal passages and throat. (This is why we get runny noses and sniffles when we cry, and why we can taste our tears when we cry).
Alternatively, the eyelids may be turned inward (a condition called “entropion”) blocking the punctae and preventing drainage. Another problem may be long hair acting as a wick drawing tears from the eye to the skin, especially in breeds where hairs actually grow on the caruncle. This hair may be kept trimmed; though, if the hair is part of the nasal skin fold of a brachycephalic breed, surgery may be needed to remove or alter the skin fold.
Old infections or injuries may cause enough scarring to close the punctae, canaliculi, or nasolacrimal ducts. Sometimes a vigorous flushing of saline through the ducts (performed under general anesthesia) can re-open them. Sometimes the puncta are congenitally closed (common in poodles and cocker spaniels) and can be surgically re-opened.
It is fairly easy to determine if there is a problem with drainage in a non-invasive way (sometimes called the "Jones test.") A special stain for eyes called fluorescein is dropped onto the eye and after a couple of minutes should be evident at the nostrils if the tear drainage system is intact.
If surgery is required in these delicate little drainage structures, special equipment is needed and a veterinary ophthalmologist is best consulted. For help finding an ophthalmologist for your pet visit
ADDRESSING THE STAINING
An assortment of remedies have been suggested to resolve the unsightly reddish stains that result from chronic tear drainage. Here are some comments on suggestions that we have heard:
We do not know that any of these products actually work reliably but they represent options for those who wish to attempt removal of tear staining.
Page last updated: 11/3/2019