Investigation of the effects of orally administered trazodone on intraocular pressure, pupil diameter, physical examination variables, and sedation level in healthy equids

Alexandra L. Moss From the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523

Search for other papers by Alexandra L. Moss in
Current site
Google Scholar
PubMed
Close
 BVSC
,
Rachel L. Hritz From the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523

Search for other papers by Rachel L. Hritz in
Current site
Google Scholar
PubMed
Close
 BS
,
Rachel C. Hector From the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523

Search for other papers by Rachel C. Hector in
Current site
Google Scholar
PubMed
Close
 DVM, MS
, and
Kathryn L. Wotman From the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523

Search for other papers by Kathryn L. Wotman in
Current site
Google Scholar
PubMed
Close
 DVM
Restricted access
Purchase Article

Abstract

OBJECTIVE

To investigate the effects of orally administered trazodone on intraocular pressure (IOP), pupil diameter measured in the vertical plane (ie, vertical pupil diameter [VPD]), selected physical examination variables, and sedation level in healthy equids.

ANIMALS

7 horses and 1 pony.

PROCEDURES

Food was withheld for 12 hours prior to drug administration. After baseline (time 0) sedation scoring, physical examination, and measurement of IOP and VPD, equids received 1 dose (approx 6 mg/kg) of trazodone orally. Examination and measurement procedures were repeated 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Blood samples were collected at each time point for analysis of plasma trazodone concentrations. Repeated-measures analysis was used to compare examination results between downstream time points and baseline.

RESULTS

7 of 8 equids had mild sedation from 0.5 to 8 hours after treatment; compared with baseline values, mean IOP was significantly lower from 0.5 hours to 8 hours, mean VPD was significantly smaller at 0.5 hours, and mean rectal temperature was significantly lower from 1 to 8 hours after drug administration. Adverse effects (signs of excitement in 1 equid and sweating in 4) were self-limiting and considered minor. Mean maximum plasma concentration of trazodone was 1,493 ng/mL 0.75 hours after administration, and terminal half-life of the drug was 9.96 hours.

CONCLUSIONS AND CLINICAL RELEVANCE

The described oral dose of trazadone elicited sedation with a few self-limiting adverse effects in the study sample. Drug effects on IOP and VPD may alter ocular examination findings. Further investigation is warranted prior to use of trazodone for sedation in equids, particularly those with ophthalmic conditions.

All Time Past Year Past 30 Days
Abstract Views 383 0 0
Full Text Views 9426 7344 152
PDF Downloads 2179 770 42
Advertisement