Epiphora is an abnormal overflow of tears down the face that results from either obstruction of tear drainage through the nasolacrimal (tear duct) system or overproduction of tears that overwhelms the normal drainage system. The overproduction of tears is most often a reflex, activated to expel irritating material from the surface of the eye or when significant irritation develops inside the eye. Although uncommon, epiphora may also result from overactive lacrimal (tear) glands and be unassociated with any source of irritation.
Normal dogs may occasionally have minor tear overflow or minor eye discharge. However, excessive, chronic or recurrent bouts of epiphora suggest a problem may be present.
Tears are continuously produced on the eye in most animals. With each blink of the eyelids, tears are pushed along the outer aspect of the eyelids towards the nose. A small hole called a puncta is present in both the upper and lower eyelid very close to the where the lids meet near the nose. Tears normally flow down these two drainage holes into a central collecting sac (lacrimal sac) that sits just under the skin below the eye. From this sac, a small tube or duct (nasolacrimal duct) carries the tears into the nose. In some animals the duct opens just inside the nostril. In other animals, the duct opens further back in the nose. The tears also help keep the nose and nostril moist.
While tears are typically colorless, they can dry to a dark red-brown-black crust. Chronic tearing can result in a brown to rust-colored staining of the hair around the eyes and face of animals. This is believed to be due to porphyrins or other pigment-like substances present in the tears. These same substances may also be present in saliva and cause similar staining of the hair when the dog chronic licks are certain area.
Tears that spill over onto the face can also be irritating to the skin of the face. Moisture and bacterial build-up in that area aggravates this irritation. Causes
Epiphora can be caused by numerous conditions. Some common causes of tear flow obstruction include: Congenital deformity resulting in failure of one or more of the drainage holes to be open (imperforate puncta). This condition is most common in the American cocker spaniel.
Inefficient drainage of tears from partial closure of the drainage openings, increased kinking of the drainage duct in the nose, or wicking of tears onto hairs that sit in the crease where the eyelids meet. This combination of problems is common in certain breeds of dogs, such as the Maltese terrier, Bichon frise, miniature poodle, Pomeranian, American Eskimo and Shih tzu.
Abnormally small tear duct openings
Inflammation within or near the tear duct system
Tear duct scarring after severe conjunctivitis
A foreign body lodged within the tear duct . This is most common in outdoor, hunting-type dogs
Epiphora can also result when tear production increases due to irritation of the eye or stimulation of the tear glands. Common causes of epiphora in this group include:
Hair rubbing on the eye from deformities of the eyelids, eyelashes growing in an abnormal location (distichiasis), or hair growing in a direction that bring it close to the eye (trichiasis)
Inflammation of the eyelids themselves (blepharitis)
Keratitis, or inflammation of the cornea
Corneal ulcerations, abrasions, scratches, wounds
Foreign body on the surface of the eye or exposure to irritants, such as smoke, chemicals, and soaps
Anterior uveitis, or inflammation of the iris and ciliary body
Irritation or stimulation of tear glands from topical eye medications
Irritation from suture material around the eye from a recent surgery
Infection or irritation around or under the eye or within the eye socket (orbit)
Tearing with eating, which is a rare form of stimulation of the tear glands
Some of the above disorders cause both obstruction of tear flow and excessive tearing.
What to Watch For
Watery discharge from one or both eyes
Possible tear staining on face below the eye, near the nose
Accumulation of dried discharge on the edges of the eyelids
Ulceration and irritation of the skin below the eye, near the nose
Rubbing of the eyes or face
Redness of the conjunctiva
Dramatic color change or cloudiness to the surface or within the eye
Possible pain with excessive squinting or blinking of the eyelids
Possible swelling of the eyelids or face around the eyelids
Possible reduction or loss of sight
Possible change in size of the pupil or eyeball