Introduction

Alpha₂-agonists such as medetomidine and dexmedetomidine are the most preferred sedative drugs in cats. Both drugs can induce vomiting and alter intraocular pressures (IOP) during vomiting and sedation period.

Objectives

The aim of this study is to compare the effects of medetomidine and dexmedetomidine on the results of tonometry and their reverses with atipamezole in cats.

Methods

Twenty cats were randomly divided into two groups of ten. The first group was sedated with 40 mg/kg dexmedetomidine(DEX) and the second group was received 80 mg/kg medetomidine(MED), intramuscularly. The vomiting cats were included. IOP were measured before administration (T₀), just after vomiting, 20 minutes intervals during 1-hour period (T₂₀, T₄₀, T₆₀) and 20 minutes after atipamezole treatment (T_AA).

Results

The base line IOP in mm Hg in MED and DEX were 21±4 and 19.5±3, respectively. While IOPs were increased in DEX (21.5±4), they were decreased in MED (19.5±6) after vomiting. IOPs continued to decrease significantly at T20, T40, and T60 in both groups. They were 16±1, 15±2, and 16±3 in MED and 16±2, 15±2, 16±2 in DEX, respectively. IOPs were increased to the baseline level at T_AA. The difference within time points were statistically significant in both groups, while there were no significant differences in the IOPs between groups in any time points.

Conclusions

A significant change was recorded in IOP in ocular healthy cats and these alterations can be reversed with atipamezole. The IOP effect must be taken into consideration when planning premedication with medetomidine or dexmedetomidine in cats.