Common causes of tearing
The medical term Epiphora means excessive tearing. When we examine the causes of Epiphora, we can generally narrow it down into two broad categories: excessive tear production or insufficient tear drainage.
Tearing is the right reaction of the eyes when something irritates them. Dust, chemicals, smog, and smoke can cause increased tearing in cats as in humans. When the irritant goes away, the epiphora usually dissolves. However, sometimes the irritant persists and the tearing becomes chronic.
A common cause of Epiphora in cats is a condition called entropion, which occurs when the eyelid (usually the lower eyelid) rolls inward. The fur on the eyelid is in direct contact with the cornea. Anyone who has ever had a grain of sand or a stray eyelash in their eye knows that the cornea is burdened with pain receptors and the constant contact of the hair with the cornea leads to persistent tearing.
Applying ointment to the cornea can soothe the eye and help create a barrier between the hair and the cornea, but this is only a temporary solution. The entropion is treated surgically: a wedge of skin below the affected eye is removed and the edges of the defect are sewn together. This will cause the eyelid to curl outward, which will remove the hair from the cornea and give the cat some relief.
Corneal ulcers (scratches or abrasions on the corneal surface) are another cause of Epiphora. These are quite painful, causing redness, squinting, and tearing, and the cat rubs the eye frequently. If left untreated, a corneal ulcer can persist and progress, and if the ulcer goes deep enough the eye can tear and vision can be lost. (More about corneal ulcers and how to treat them in my column from last year’s September / October issue of Catster, which is online at catster.com.) Infections, allergies, and other types of eye injuries also cause excessive tear production.
Now that we’ve ruled out the most common causes of excessive tear production, let’s focus on tear drainage issues. Typically, tears flow from the cat’s nose and throat through a small channel in the inner corner of the eye. Sometimes the tears cannot drain because the opening of the duct is blocked. Cats who have had an eye infection from severe respiratory infections (often as kittens, especially if they came from a shelter or pet store) often develop scars around the opening of the tear duct that prevent proper drainage.
If a blocked tear duct is suspected, a cannula (of course for cats under anesthesia) can be inserted into the tear duct to try to loosen it. Some cats have a blocked tear duct because the tear duct was unable to open while the cat was developing. This can be corrected surgically. Brachycephalic cats (flat-faced breeds such as the Himalayas and Persians) usually have anatomical abnormalities in their tear ducts. This, along with their large eyes and shallow eye sockets, predisposes these breeds to Epiphora. The tears do not penetrate the tear duct and instead roll down her face.
Diagnosis and treatment
Diagnosing a feline tear problem is easy (and actually a bit of fun). A drop of fluorescent yellow dye is placed in the cat’s eye. The tear duct runs from the corner of the eye to the nose. When the channel is open, the dye enters the nose and the cat’s nose appears to glow in the dark under black light. It looks freaky and kids find it fascinating. (Even in adults!) If the nose does not glow, we cannot say with 100% certainty that the tear duct is blocked, but it would certainly require further investigation.
When an underlying cause of Epiphora can be identified and treated, most cases will go away. However, cats with anatomical problems are likely destined to have watery eyes and wet faces. Tears contain a small amount of pigment, and light-colored cats may have some reddish-brown tear stains on their fur under their eyes. The staining is harmless, but many owners find it unsightly.
A variety of products are available to minimize staining; However, a veterinarian should be consulted beforehand to ensure that the product is safe and FDA approved. Products containing antibiotics should be avoided as they can lead to bacterial resistance. I also recommend avoiding products containing hydrogen peroxide as it can be very irritating if it accidentally gets in your eyes.
Dry those tears
Here is a selection of products available to help prevent cracks and stains. You can find tear stain prevention products at chewy.com and other pet supply retailers: