Estimated reading time: 2 minutes
by Dr Eythan Walsh, Northern Suburbs Veterinary Hospital, Greensborough, VIC
The Shirmer tear test is used to diagnose dry eye in dogs and cats. The paper strips are positioned on the cornea and left for a minute to measure tear production.
What’s good about it
The test is quick, easy to administer and cheap to purchase. It’s the mainstay of diagnosis for dry eye, which is quite a common condition. When the eye is not receiving enough lubrication, it often leads to a slight mucoid discharge. The eye can become dried out and is prone to developing ulcers and other associated problems.
Administering the test can be uncomfortable for the animal but they generally tolerate it very well. Some animals will toss their head around and some will just sit there quietly. Their reaction is very much on a case-by-case basis.
Markers printed on the strips in millimetres indicate the quantity of tears that are being absorbed. The strips are also impregnated with blue dye to make it easy to read the results. If the absorption doesn’t meet certain thresholds, then a diagnosis of dry eye can be given.
What’s not so good
The success of the test is user-dependent. The strip needs to be positioned on the correct part of the cornea or there will be an inaccurate result. The test can be a bit uncomfortable for the animal but local anaesthetic in the eye needs to be avoided as it interferes with tear production. It’s also important to avoid getting oil from your fingers onto the test strips as that will impact on the test results too.