Dry Eye in Canines
Keratoconjunctivitis Sicca, or dry eye, is a condition that affects the aqueous portion of a dog’s tear film, resulting in dry, red, irritated eyes. There are many causes of dry eye in dogs, but all require treatment to prevent pain and ongoing damage to your pet’s eyes. In the following article, I will discuss KCS, as well as the common testing and treatment options that are available.
Many factors can cause KCS, and in it, either or both eyes may be affected. The most common cause of dry eye is an immune-mediated disease; this means that for unknown reasons, your dog’s body has decided to attack the nictitans and lacrimal glands in your dog’s eyelid, destroying the portion of the glands that produce tears.
Other suspected causes of KCS include endocrine diseases (hypothyroid disease, diabetes), drug reactions, infections, trauma to the eyelid, or previous surgical removal of these glands of the eye. There is also a neurogenic form of the disease, which can occur as a secondary result of trauma, which affects the nerves leading to the eyelid, or, more rarely, cancer.
KCS is a fairly common disease affecting dogs’ eyes, with certain breeds predisposed. The English Bulldog, West Highland White Terrier, American Cocker Spaniel, Lhasa Apso, Shih Tzu, Pug, Miniature Schnauzer, and Yorkshire Terrier all appear to be predisposed to develop dry eye.
Dogs with dry eyes will likely have evidence of irritation and inflammation to their eyes. You may note that one or both eyes are red and painful. Many times, an accompanying mucoid discharge will be present. Secondary complications from dry eye may result in corneal ulcers and even corneal ruptures. Please note that it is very easy to confuse these symptoms with other ocular diseases.
When you take your dog to the Veterinarian, a history will be taken; this should include when you first noticed symptoms, if your dog is squinting more frequently or pawing at his eyes, and if any other problems have been noticed at home. Your veterinarian will then perform a comprehensive examination before moving on to an ocular exam.
During that Examination, first, a small white strip of paper may be applied to your dog’s eye. This is called a Schirmer Tear Test and is a measure of tear production. Dogs with dry eyes will produce less than 15 mm of tears in a one-minute test. Following a tear test, a yellow dye may be placed in your dog’s eye to evaluate for a corneal ulcer, which can occur secondary to KCS.
If a diagnosis of KCS is made, ophthalmic treatment will be started to help control the condition. Fortunately, many dogs respond to one of several medications, which can be placed in the eye 1-2 times daily. While these medications are often not a cure, they can effectively help the eye start making tears again. If a secondary bacterial infection is also suspected, ophthalmic antibiotics may also be prescribed. In rare cases, surgical management could be considered when ophthalmic treatment has been unsuccessful.
If you suspect your dog has a dry eye, it is crucial to make an appointment with your veterinarian to evaluate your dog’s eyes. KCS is a disease that can advance quickly, leading to corneal ulcers and ruptures if not diagnosed and appropriately managed.
Jeffrey Stupine, V.M.D.
Medical Director, World of Animals Veterinary Hospitals