Quarterly Newsletter

July-2013-KCS_WoundMgt

The IVG Hospitals Quarterly Veterinary Newsletter features articles of interest to the veterinary medical community, written by veterinarians and veterinary specialists at our four locations.

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Diagnosis and Treatment of Keratoconjunctivitis Sicca Ruth Marrion, DVM, DACVO, PhD KERATOCONJUNCTIVITIS SICCA (DRY EYE) IS ONE of the most common ophthalmic diseases affecting pet dogs. Despite its prevalence, it is underdiagnosed and therefore often not treated. My goal in writing this article is to encourage veterinarians to perform a Schirmer tear test regularly as part of a complete ophthalmic examination. Once a diagnosis of dry eye is established, treatment can be tailored to the individual patient's needs. THE RED EYE Dogs are often presented to veterinarians for a red, painful eye. The most common causes are: • • • • Keratoconjunctivitis sicca Corneal ulceration Uveitis Glaucoma By performing a complete ophthalmic examination, veterinarians can determine which of these conditions, if any, is responsible for a patient's condition. When a patient is presented for a "Red Eye", I recommend the following tests: • • • • Schirmer tear test Fluorescein stain Tonometry Menace and palpebral response THE SCHIRMER TEAR TEST Schirmer tear test strips come in packages of two strips, one labeled R and one labeled L (See Fig. 1). The package opens to the squared-off handle end of the strips. The examiner is meant to hold this end of the strip, and insert the round end of the strip posterior to the lower eyelid, with the notch at the eyelid margin. The examiner should not touch the round end of the strip, since oil and debris from the hand may affect the tear strip reading. The tear strip should be held in place for one minute and the number registered on the strip recorded (Video 1). Normal tear production in dogs |1| Ruth Marion, DVM, DACVO, PhD practices at Bulger Veterinary Hospital in North Andover, MA. Dr. Marrion with one of her avian patients; a raven from the Blue Hills Trailside Museum. is greater or equal to 15 mm/min. Other tests should be performed FOLLOWING tear measurement, since application of substances to the surface of the eye can alter tear test readings. Applying fluorescein stain or eye wash can result in a falsely increased reading. Conversely, application of topical anesthetic blocks stimulation of reflex tearing and artificially decreases the Schirmer tear test reading. ADDITIONAL DIAGNOSTICS If the veterinarian determines that a patient has dry eye, there are several questions to be answered: Does the dog have an ulcer? Apply fluorescein stain following Schirmer tear test. How well does the dog blink? Many dogs with dry eye also have a poor blink, leading to chronic exposure of the axial cornea and associated ulceration and/or scarring. Test the dog's palpebral response by touching the skin at the lateral and medial canthus (Fig. 2). A dog with a normal palpebral response will blink completely in response to a light touch on the periocular skin. Is a secondary bacterial infection present? I frequently perform conjunctival cytology to determine if a secondary bacterial infection is present. Most dogs are amenable to this following the administration of topical anesthetic. For this test, I use the handle end of a scalpel blade. Place

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