What you Need to KNOW!
Current approved treatments for canine dry eye consist of cyclosporine drops, which helps suppress the immune system from causing inflammation. Many dogs respond well, but others are faced with chronic inflammation and even cloudiness of the cornea despite the best treatment for dry eye in dogs. Efforts are underway to develop alternate approaches to immunusuppression which target inflammation and cornea cellular integrity and function. Recently, science suggests a role between altered antioxidant levels and tear production, and reinforces that concept of antioxidant use in ocular health.
Canine dry eye research is also focused on providing antioxidants and cellular protection to the eye, since a dog with dry eye can have cloudiness of the cornea, and irritation of the conjunctiva and cornea. Remember, the cornea and surrounding tissue require nutrition and cellular factors to function correctly. Formulations containing multiple factors, such as glutathione, carnosine, taurine, and other cellular protecting factors are new approaches to supporting a healthy cornea, ocular clarity, and overall ocular health.
About Canine Dry Eye
Dry eye in dogs is actually a lack of tear production, causing the eye to become dry. Tear production is crucial to the health and well-being of the eye. Tears not only lubricate the eyes but nourish them with antimicrobial proteins, sugars, salts and oxygen (1). Tears consist primarily of water. Other components of tears are oils and mucous. Tears are secreted by two tear glands called lacrimal glands. One is located above the eye and one is located within the third eyelid (the third eyelid is also known as the nictitating membrane). During dry eye the water content of the tears is decreased hence the yellow/green discharge indicative of dry eye is produced from the remaining oil and mucous. Dry eye in dogs is also known as keratoconjunctivitis sicca; “kerato” being the cornea or the covering of the outer eyeball, “conjunctivae” are the pink mucous membranes around the eyeball; “itis” is inflammation and finally “sicca” means dry. This name is abbreviated KCS and may be used by veterinarians instead of the phrase dry eye. It is important to have a veterinarian diagnose dry eye early so that damage to the tear glands can be kept to a minimum.
Dry eye in dogs is diagnosed by measuring the tear production of the eyes. This is done with something called a Schirmer tear test. A special strip of paper is placed underneath the lower eyelid and held there for 60 seconds. The paper absorbs the tears and a measurement is seen that determines whether tear production is normal or not. If tear production is abnormal, this test will show the severity of dry eye. Symptoms of dry eye in dogs may have variable or subtle symptoms. Early in the condition there may be little or no symptoms seen. Dogs with dry eye may blink a lot or hold their eyes shut because it is painful. Dogs that have frequent conjunctivitis and eye infections may have dry eye. Some dogs may have obvious signs of dry eye like think green or yellow discharge and the eyes may appear dry and irritated.
A specific cause of dry eye in dogs is hard to determine, although immuno-genic (immune mediated) dry eye appears to be the most common form. Genetics may also play a role because certain breeds of dog are predisposed to developing dry eye. Some common breeds affected by dry eye are the English Cocker Spaniel, West Highland white terrier and the Pug. Owners of these breeds may choose to have the Schirmer tear test performed during a routine exam with a veterinarian to catch dry eye early. Another cause can be from distemper virus, whcih attacks all bodily interfaces. Dry eye in dogs is one of the collections of symptoms involved in infection with distemper virus. Blunt trauma and damage to either of the tear glands may also cause dry eye in dogs. There is evidence to suggest that a dog’s own immune system may play a role in dry eye by damaging the tear glands. Treating dry eye in dogs can be frustrating.
There are several products available today that alleviate varied specific symptoms of dry eye. Topical immune-suppressants are now commonly used to suppress the immune response within the tear glands. A more effective target for treatment may be maintaining the health of the healthy eye to prevent any damage to the tear gland initially.
- Brooks, Wendy. 2010. Dry eye (Keratoconjuntivitis sicca). The Pet Health Library. Veterinary Partner Online. Veterinarypartner.com. March 15, 2012.