Comparative clinico-physiological effects of the α2-adrenoceptor agonists; Xylazine and medetomidine in dogs

Abstract EN

This study was conducted to compare the effects of xylazine (XYL) and medetomidine (MED) on some clinico-physiological values in dogs.

A prospective blinded randomized experimental trial was used with six dogs, which were allocated to two groups of three animals each.

The 1st group received intramuscular (i.

m.) XYL (2.2 mg / kg) and the 2nd group received MED (40 μg / kg, i.

m.).

Heart rate (HR), electrocardiographic (ECG) readings, blood pressure (systolic and diastolic), respiratory rate (RR), and rectal temperature were measured at 0, 5, 10, 15, 20, 30, 60 and 90 minutes from drug administration.

Xylazine and MED induced a significant (P ˂ 0.05) decrease in HR up to 60 and 90 minutes after drugs' administration, respectively.

Xylazine at a dose of 2.2 mg / kg induced marked brady-arrhythmia with sinus arrest and 1st degree A-V block, while MED induced a less pronounced arrhythmia.

Both XYL and MED induced a transient hypertension (increase in both systolic and diastolic blood pressure) that returned to normal values after 30 minutes from drugs' administration.

They also induced a significant (P ˂ 0.05) decrease in RR.

Both drugs had no significant effect on rectal temperature of the treated dogs.

It was concluded that MED is more potent and less arrhythmogenic than XYL, and the two drugs nearly have the same effects on HR, RR and blood pressure values in dogs.