Dry Eye in Dogs

Tear production is an essential part of lubricating and protecting the eyes. Sometimes, tear production can be impaired by a number of conditions, including allergies, local swelling, and infection. While usually not serious if treated promptly, dry eye can be a symptom of Canine Distemper Virus and should be addressed as soon as possible. Since tears are responsible for carrying away waste products, foreign material, and infectious particles from the eyes, reduced or arrested tear production can allow infection, damage to the cornea (outer layer), or irreversible scarring to damage your pet’s eyes. See a veterinarian right away if you notice any unusual mucous production or redness around the eyes.

• Redness around the eyes
• Mucous production (usually yellowish)
• Brownish tint to the eye surface
• Excessive blinking
• Discharge of mucus, pus, or liquid from the eye
• Rubbing at the eyes and whining
• Loss of vision (severe circumstances)

• Infection of the tear duct or eye
• Trauma to tear gland or duct
• Autoimmune reaction attacking tear gland
• Blocked tear duct
• Breed-related predisposition – commonly seen in Pugs and Yorkshire Terriers

Owners who notice their pet’s eyes becoming reddened with mucous discharge and discomfort should see the veterinarian right away. The veterinarian will diagnose dry eye based on a visual inspection of the eye and assess the severity of the condition using the Schirmer Tear Test. For this test, a piece of specially-made paper is brought into contact with the lower eyelid at the outer corner of the eye and allowed to absorb for 60 seconds. The length of moistened paper at the end of the test gives a quantitative assessment of the eye’s ability to moisten itself. If the length is measured at less than 10mm, your pet has dry eye. Less than 5mm is considered severe. A healthy tear duct should moisten the paper to 15mm or more.

More difficult is diagnosing the cause of the dry eye. In many cases the immune system accidentally targets the tear gland, destroying the tissue. This is most common in American Cocker Spaniels, Miniature Schnauzer, and Highland White Terrier. In other cases, trauma to the tear duct (such as a bump on the snout during play) may resolve on its own, but the swelling should be controlled with appropriate measures. A visual inspection of the animal’s head will reveal this to be the case.

Sometimes an infection can obstruct the tear duct. If an infection (whether primary or secondary) is suspected, a swab of the mucous can be sent to the lab for culturing.

The treatment for dry eye will depend on the primary cause, which can be obscured by secondary problems. In many cases, pre-existing inadequate tear production can allow infections to invade the conjunctiva. Antibiotic drops are most commonly prescribed to clear up the infection. This is an important step, because often the primary cause is the immune system attacking the tear gland, for which the treatment is immunosuppressants. Giving immunosuppressants while an active infection is occurring can lead to serious problems. Thus, infections must be addressed before the preferred treatment of Cyclosporine. This medication is highly effective in treating autoimmune dry eye, so much so that 80% of patients even with severe cases respond to the treatment. Additional treatments include rewetting drops, and drops that help to dissolve thick mucous. These treatments are low-risk and may easily be administered at home.

In rare cases such as that of severely obstructed tear glands, or tear glands that have been damaged to the point of inadequacy, a surgical option may be desirable. The veterinarian may refer you to a canine ophthalmologist, who will carefully re-route one of your dog’s salivary glands to the tear duct. Saliva direct from the salivary gland is actually an excellent replacement for tears, and can completely correct severe obstructive dry eye. However, during meals the increased saliva production may cause your pet to weep dramatically. This of no medical concern, but some owners may find this distressing.

In most cases, Cyclosporine eyedrops will need to be administered once a day. In severe cases, they may need to be administered as much as three times a day until the condition improves, upon which a daily dose of once per day usually is enough to keep the condition in check. Return visits to the vet are needed especially after a few days of treatment to check how your dog is responding to the medication.

If your pet does not have autoimmune-induced dry eye, or does not respond to the Cyclosporin, rewetting drops may need to be administered 4-6 times a day, depending on the severity of the condition. After surgical correction, the saliva may occasionally leave mineral deposits in the eye, and so eyedrops to correct this will need to be administered periodically.

In any case, most dogs respond well to dry eye treatments, and if addressed promptly, most escape with no permanent damage.