In most instances of canine Keratoconjunctivitis Sicca (KCS) it is difficult to tell the initial cause of your dog’s dry eyes. Usually, though, the problem is due to one of these three conditions:
- Small ducts that carry tears to the eyes are blocked
- Tear duct nerves are not working and thus cannot stimulate tear glands in the eyelid to secrete enough tears
- Tear glands themselves are not working due to an infection
In some cases a dog may suffer from a combination of all three problems.
Damage to the Tear Glands
Immune-mediated destruction of the tear glands is the most common cause of KCS. How this inflammatory reaction develops is not clearly understood, but it seems to be more common in female dogs and certain breeds of dogs, including: the American Cocker Spaniel, the Miniature Schnauzer, English Bulldog, Lhasa Apso, and the West Highland White Terrier.
Damage to the tear glands can also be one of the many symptoms associated with canine distemper. Other conditions such as kidney disease and uterine infections can affect a dog’s tear glands as well and temporarily cause dry eyes.
Loss of Nerve Function
Facial nerves stimulate the tear glands in dogs. Because these nerves pass through the middle ear, long-standing ear infections can damage the nerves, and lead to very little tears being secreted. The same problem can result from nerve damage that occurs for other reasons such as injuries to the face and head.
Damage to Ducts
Chronic conjunctivitis, especially, can lead to scarring of your pet’s eye lids. As a result, ducts that carry tears from the glands to the eye can become plugged. This means that tears will not reach the eye.
Less Common Causes
Several other rare conditions can lead to dry eyes.
- In some cases, dogs may be born without tear glands
- Some sulfa-containing drugs can cause temporary or permanent KCS
- If the third eyelid is removed due to cherry eye, the eye may not be able to secrete adequate tears
- A hormone imbalance related to hypothyroidism may cause KCS
- Anesthesia administered during a surgical procedure can cause temporary dry eyes (veterinarians should lubricate your dog’s eyes before any procedure to avoid the problem)
- Injuries to the eyes can also cause damage that leads to dry eye
Identifying the cause of chronic dry eye is the first step in treatment. Make sure you pay attention to the signs and symptoms, and if you see something, talk to your vet. Otherwise your dog could be left with a very itchy problem.
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.