Overview of Canine Epiphora (Excessive Tearing)
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 in dogs, 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 of Tearing in Dogs
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) Conjunctivitis 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 Glaucoma 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
Diagnosis of Epiphora in Dogs
Veterinary care often includes diagnostic tests to determine what is causing the epiphora or ocular discharge. Epiphora is initially classified into one of three categories: Obstruction of tear flow through the nasolacrimal duct system Reflex stimulation of tears due to ocular irritation Overproduction of tears by the lacrimal glands (least common)
Once a specific diagnosis has been established, appropriate treatment can be instituted.
There are several potential diagnostic tests. Your cat may be referred to a veterinary ophthalmologist for further evaluation and completion of some of these tests, which may include: Complete ophthalmic examination including a magnified examination of the eyelids, tear drainage holes (puncta), conjunctiva, cornea and front chamber of the eye Schirmer tear test to determine if tear production is below normal, normal or excessive Fluorescein and possibly Rose Bengal staining of the cornea to assess for the presence of ulcers, lacerations or scratches Tonometry to measure the pressure within the eye to evaluate for the presence of glaucoma Flushing of the tear duct system with saline to determine if it is open all the way to the nose Dacryocystorhinography is the flushing of the entire tear duct system with a contrast agent that is visible on X-rays. It is a special X-ray technique that helps outline the tear drainage system from the corner of the eye all the way to the nose. This X-ray study may be done when congenital absence of part or all of the nasolacrimal system is suspected, or when compression, cystic dilatation, scarring or obstruction of the system is suspected. It is performed under general anesthesia.
Treatment of Epiphora in Dogs
The goals of treating epiphora include 1) eliminating any causes of excessive tearing, 2) eliminating any obstruction to tear flow (if possible), 3) decreasing the irritation caused by the tears themselves, and 4) keeping the face and area around the eye dry and clean. Specific treatment depends on the cause of the epiphora or ocular discharge. There is no general nonspecific treatment for epiphora.
Treatment of Eye and Orbital Disorders Once the underlying eye condition is diagnosed, appropriate therapy is started for that condition. As the underlying problem improves, the epiphora also gradually subsides. Some deformities of the eyelids, eye lashes and facial hairs require corrective surgery in order to eliminate the irritation and the epiphora. Topical medications that cause epiphora are usually stopped and replaced with a less irritating medication. Infections may require both topical and oral medications. Some forms of blockage of the tear duct system are not correctable and the epiphora can be expected to be chronic.
Management of Chronic Epiphora When the cause of the epiphora cannot be corrected, or corrective measures fail to resolve the tearing completely, then a daily maintenance routine may be necessary to decrease the adverse effects of the epiphora. The area around the eye, especially towards the nose, is washed and dried each day using a gentle cloth and lukewarm water. Topical eye antibiotics and/or anti-inflammatory medications may be needed periodically to decrease irritation caused by the epiphora. Oral tetracycline therapy may be used for short periods of time to reduce severe tear staining of the hair around the eyes and face. Tetracycline is an antibiotic that concentrates in the tear glands and chemically changes some of the components of the tears. As a result they are less irritating to the skin and cause less staining. Oral tetracycline should not be use long-term in dogs because it may cause liver disease. It is also not recommended in animals less than seven months of age, as it will cause yellow discoloration of the developing permanent teeth. Oral tylosin may also decrease tear staining and can be used for longer periods of time than oral tetracycline. Tylosin is an antibiotic that comes in a powder form and is usually administered on the food.
Recommendations for home care depend upon the underlying cause of the problem. In addition, some general care is necessary to maintain the health of the eye.
Gently clean away any eye discharge with a sanitary cloth or tissue, and keep the area clean and dry until the cause of the problem is identified.
Do not delay in bringing your pet to a veterinarian for examination as some causes of epiphora, especially those sudden in onset, are potentially vision threatening and require immediate medical or surgical attention.