Assessment of tear film osmolarity using the IPenVet osmometer in Pug and Shih-Tzu dogs with and without keratoconjunctivitis sicca.

Abstract

OBJECTIVE: To establish tear film osmolarity (TFO) values in Pugs and Shih-Tzus, with and without keratoconjunctivitis sicca (KCS). ANIMALS STUDIED: A total of 82 adult dogs were evaluated. PROCEDURE: The inclusion criteria for the healthy group was a Schirmer tear test (STT-1) &#x2265;15&#xa0;mm/min with no clinical signs of KCS, whereas those with KCS had clinical signs and a STT-1 &#x2264;10&#xa0;mm/min. All animals underwent complete ophthalmological evaluation prior to STT-1 and TFO. Student's t tests were used to compare STT-1 and TFO in KCS and healthy eyes as well as possible differences in TFO between breeds. In addition, a linear regression to model the relationship between the two variables (STT-1 and TFO) was performed. A P-value&#xa0;&#x2264;&#xa0;0.05 was considered statistically significant. RESULTS: STT-1 results were significantly lower (p&#xa0;=&#xa0;0.0001) in the KCS group (4.46&#xa0;&#xb1;&#xa0;1.74) compared with the control group (18.80&#xa0;&#xb1;&#xa0;2.02). Mean TFO results were significantly higher in the KCS group (353.02&#xa0;&#xb1;&#xa0;16.58&#xa0;mOsm/L) (p&#xa0;<&#xa0;0.0001) compared with the control group (315.27&#xa0;&#xb1;&#xa0;6.15&#xa0;mOsm/L). The formula Y&#xa0;=&#xa0;365.059-2.625 * X significantly predicts (p&#xa0;<&#xa0;0.001) the value of the variable Y (TFO mOsm/L) as a function of the variable X (STT-1&#xa0;mm/min), with a coefficient of determination of 0.71. CONCLUSIONS: The results revealed differences in TFO and STT-1 between KCS and healthy dogs. Additionally, STT-1 and TFO values were correlated with the aim to use STT-1&#xa0;values to predict TFO values in brachycephalic breeds.