Effect of auriculopalpebral nerve block on Schirmer tear test I values in normal horses.

Objective: To compare Schirmer tear test I (STTI) values collected in normal horses with and without an auriculopalpebral nerve block.

Procedure: Schirmer tear test I values were measured in 20 clinically normal horses (38 eyes) with a median age of 12 years. The order of eyes tested was randomized. Within 24-48 h, at the same time of day, tear measurements were collected again after administration of an auriculopalpebral nerve block. Each block was performed a minimum of 5 min prior to each STT I. A repeated-measures model was used to analyze differences between STT I values in eyes with and without nerve blocks incorporating within horse correlation between eyes. The mixed-model included fixed factors of treatment and eye and a random intercept for each horse. An unstructured covariance structure was used.

Results: On average, STT I values measured in eyes after auriculopalpebral nerve blocks were 0.55 mm/min greater than those without nerve blocks. This difference was not statistically significant (P = 0.5268).

Conclusions: There was no effect of auriculopalpebral nerve block on STT I values in normal horses.