Schirmer Tear Test (STT) in Dogs
Eye abnormalities are common in dogs and the causes vary. The Schirmer tear test (STT) can help determine if low tear production is an underlying cause or a contributing factor to an dog’s eye problem. Low tear production can cause significant eye inflammation and chronic eye problems. A Schirmer tear test is indicated anytime a dog has a reddened eye or has thick discharge from the eye. It is a common component of eye examinations in animals.
There are no real contraindications to performing this test in a dog with eye disease; however, it may not be necessary when excessive tearing is present. An eye that is producing lots of watery tears obviously does not have low tear production.
What Does a Schirmer Tear Test Reveal in Dogs?
A Schirmer tear test reveals the amount of watery tear production in each eye. Low tear production, also called dry eye, can cause serious and chronic inflammation on the surface of the eye.
How Is a Schirmer Tear Test Done in Dogs?
To perform a Schirmer tear test, a small strip of calibrated filter paper is placed inside the lower eyelid and left in place for one minute (60 seconds). The distance to which the tears flow along the filter paper is a measure of the volume of tears produced. Low tear production can indicate a condition known as keratoconjunctivitis sicca, or dry eye. This problem can be treated with appropriate medication once a diagnosis is made. This is a safe and non-painful test. The results of the test are available at the end of the 60-second test period.
Is a Schirmer Tear Test Painful to Dogs?
A Schirmer tear test is usually not painful, but it can be uncomfortable, particularly if the eye is already painful. The comfort of the dog can be improved during this test by placing the test strip between the outer lower eyelid and the third eyelid of the animal (holding the strip at the end of the eye closest to the nose). Unfortunately local anesthetic drops cannot be used prior to this test because local anesthesia alters the results of the test.
Is Sedation or Anesthesia Needed for a Schirmer Tear Test?
Neither sedation nor anesthesia is needed for a Schirmer tear test. In fact, to provide the most accurate results, the test should not be done in sedated or anesthetized dogs.