Goals of Treating Dry Eye
Dry eye (keratoconjunctivitis sicca or “KCS”) is a fairly common condition in companion dogs that involves insufficient production of tears. Depending on the cause of dry eye, it may or may not be curable. However, it almost always is manageable on an outpatient basis. The goals of treating dry eye are to: 1) stimulate tear production, if the tear glands can still function; 2) stabilize the tear film, so that it stays in the eyes as long as possible; 3) eliminate eye redness and irritation; 4) control inflammation; 5) treat any accompanying eye or ear infections; and 6) resolve any corneal ulcers or associated skin damage.
Treatment Options for Dogs with Dry Eye
Medical (drug) therapy is the main method of treating dry eye, as well as most other diseases that cause a tear deficiency in dogs. Almost all of the available drugs are administered topically, which means that they are put directly on or into the eye, usually in the form of drops or ointments. Before any topical medication is applied, the area around the dog’s eyes should be gently but thoroughly cleaned to remove any fresh or crusty remnants of ocular discharge. There are a number of prescription drugs that can stimulate tear production, as long as the tear glands are still functioning. These are called “lacrostimulants.” One of the newer lacrostimulants is a drug called “cyclosporin.” Cyclosporin suppresses the dog’s immune system and can stabilize or even reverse immune-mediated damage to the lacrimal (tear) glands, which in turn can restore tear production. Cyclosporin usually is prescribed as an ointment for dogs with dry eye. Other lacrostimulants are also available for use in veterinary medicine. The results of treatment with lacrostimulants are not immediate. Artificial tear supplements, and possibly antibiotics if a bacterial infection is identified, may be helpful until the effects of the medication kick in. If lacrostimulants are effective in stimulating tear production, treatment usually will continue for the rest of the dog’s life. The dog’s attending veterinarian will determine the best treatment protocol.
If the functional tissue of the lacrimal glands has been irreversibly damaged, cyclosporin or other lacrostimulants will not be able to stimulate those glands to make tears. In such cases, dogs with dry eye will need to have tear substitutes applied regularly to keep the surface of their eyes lubricated and to reduce irritation and discomfort. These medications are called “lacrimomimetics” or “artificial tears.” They will need to be applied several times a day for the life of the dog, to keep its eyes sufficiently moisturized and protected. Ointments require less frequent application than drops and tend to be less expensive in the long run.
Topical drugs are available to help reduce the build-up of mucus that so often accompanies dry eye. Antibiotics with broad spectrum activity can be used if a bacterial infection is present or if the cornea is ulcerated; these can be applied directly to the surface of the eye or given orally. Antibiotics usually are only prescribed when pus is present. Anti-inflammatory medications (non-steroidal anti-inflammatory drugs [NSAIDs] or corticosteroids) may be a valuable adjunct to other therapy for dry eye. However, steroids should not be used in dogs with ulcerated corneas, because they can increase the risk of corneal rupture.
If medical treatment doesn’t bring the dog’s symptoms under control, there are several surgical procedures that may help. These usually are only considered as a last resort. One surgical option is a “parotid duct transposition.” This re-routes the duct of the salivary gland (the parotid duct) into the inner pocket of the dog’s eye, so that saliva can act as a tear-film substitute. One of the downsides of this procedure is that it can cause too much fluid to coat the eye, beyond what the dog’s normal drainage system can handle. In addition, saliva can be irritating to the cornea. Another surgical option is a “permanent partial tarsorrhaphy.” This procedure involves suturing parts of the upper and lower eyelids together, to reduce exposure of the eye surface to the environment, enhance blinking and conserve tears. The dog’s veterinarian can discuss these options with the owner in much greater detail.
The prognosis for dogs with dry eye varies, depending upon the cause of the condition and the conscientiousness of the owner in maintaining a regular treatment schedule. While a complete cure is not always possible, effective management of the condition almost always is. Dogs with dry eye caused by an immune system abnormality probably will need to be treated daily for the rest of their lives. Good hygiene is important for any dog with this disorder. The discharge and debris that accompany dry eye should be removed regularly to the risk of corneal ulceration and to keep inflammation at bay. The animal’s vision may be permanently affected if dry eye is not diagnosed and treated at an early stage. Long-term management of this condition is time intensive and can be challenging for owners. Fortunately, dry is not a life-threatening condition.