Effect of acepromazine or xylazine on tear production as measured by Schirmer tear test in normal cats.

Objective: To evaluate the effect of acepromazine or xylazine on Schirmer tear test 1 results in clinically normal cats.

Animals: Sixteen healthy cross-breed cats.

Procedure: The animals were randomly divided into two groups of eight cats each. The first group was sedated with acepromazine alone (0.2 mg/kg) and the second group received only xylazine (2 mg/kg). All cats had Schirmer tear test (STT) readings taken prior to sedation and at 15 and 25 min postsedation.

Results: Sedation with acepromazine or xylazine in cats with normal pre-sedation STT 1 values caused a statistically significant decrease in mean values of tear production in both groups. In acepromazine group the mean +/- SEM STT at T(15) and T(25) were 4.31 +/- 0.98 (P < 0.001) and 5.18 +/- 1.07 (P = 0.002). The post-treatment mean +/- SEM values in xylazine group were 2.18 +/- 0.97 (P < 0.001) and 2.62 +/- 1.17 (P = 0.001) at 15 and 25 min respectively. Comparison between T(15) and T(25) in acepromazine group (P = 0.49) and xylazine group (P = 0.56) revealed no significant differences.

Conclusion: These observations indicate that both acepromazine or xylazine significantly reduced tear production in clinically normal cats. In cats, clinicians should measure STT values prior to utilizing acepromazine or xylazine as sedatives in order to accurately assess the results. Moreover, sterile ocular lubricant or tear replacement should be used as a corneal protectant during sedation with these drugs.