Oral trazodone results in quantifiable sedation but does not result in a xylazine-sparing effect in healthy adult horses.

The research article evaluates the effect of trazodone, a medication used to treat depression and anxiety in horses. It focuses on the effects of two different dosages of oral trazodone on sedation and the subsequent requirements for another sedative agent, xylazine.

Objective and Methodology

• The aim of the study was to investigate the sedation levels and the necessary intravenous (IV) amounts of xylazine required to achieve a 45% reduction of head height above ground measurements in horses after administering two dosages of oral trazodone.
• Eight healthy mares of different weights and breeds from a university teaching herd were used in the experiment. The experiment was a double-blind cross-over study, where neither the subjects nor experimenters know which group is receiving which treatment.
• The horses were divided into three groups for oral treatments: one with no trazodone (control group), another with a low dose of trazodone at 3 mg/kg, and the third group with a high dose of trazodone at 6 mg/kg.
• Key measures such as cardiac auscultation, sedation score using EquiSed sedation score and head height above ground were taken before and 120 minutes after treatment. After these measures, xylazine was administered intravenously until the head height achieved is 45% of the baseline.

Results

• The study revealed that trazodone administration significantly improved sedation scores and reduced head height above ground, indicating an increase in sedation.
• However, researchers discovered that xylazine dose requirements were increased when a low dose of trazodone was administered while remaining unchanged with a high dose.
• The variance in results led to the conclusion that oral administration of low-dose trazodone might increase the requirement of xylazine, effectively not serving as an alternative or supplement to xylazine sedation in horses.

Conclusions and Recommendations

• The research suggests that oral trazodone increases quantifiable sedation in horses. However, low-dose trazodone might also increase the need for xylazine.
• The authors emphasize that additional clinical research is necessary to fully understand the implications of this finding on other parameters such as cardiovascular physiology in horses.