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(EXCESSIVE TEAR PRODUCTION IN DOGS AND CATS)
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Watery ocular discharge is a common concern of pet owners. Excessive tears drain down the pet’s face and, in time, the chronic exposure to moisture produces skin
irritation, infection, and odor. The fur becomes stained reddish brown due to tear pigments, an especially non-cosmetic problem in white-furred pets. The medical term for
this condition is “epiphora” and it is one of the most difficult conditions to resolve in all of veterinary ophthalmology.
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There are two causes of Epiphora (excess tearing) in pets:
irritation to the eye and abnormal tear drainage.
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), or more commonly from eyelash 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 onto the eye and
cause irritation. Eyelashes can grow at abnormal angles and rub on the eye. Eyelashes can even grow on the inner surface of the eyelids 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 The Pet Web Library or the Vaccine Mezzanine:
NORMAL TEAR DRAINAGE
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 puncta. These are essentially drainage holes for tears. The puncta 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 when we cry, why
we sniffle when we cry, and why we can taste our tears when we cry).
There are many problems that can occur along this drainage route. One common problem, especially in the poodle and the bichon frise as well as brachycephalic breeds,
is simply that the eye socket is shallow. This means that tears over flow from the corner of the eye because the eyelid space there is not deep enough to contain them. These
tears never make it to the puncta and instead spill down the sides of the nose. This condition, if present, cannot be repaired; it is simply the conformation of the dog’s face.
Alternatively, the eyelids may be turned inward (a condition called “entropion”) blocking the puncta and preventing drainage. Another problem may be long hair acting
as a wick drawing tears from the eye to the skin. 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 scar the puncta, canaliculi, or nasolacrimal ducts closed. 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.
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 www.acvo.com
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:
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