COMPARISON OF 3 DOSES OF DEXMEDETOMIDINE WITH MEDETOMIDINE IN CATS FOLLOWING INTRAMUSCULAR ADMINISTRATION

Cats (n = 6) were administered dexmedetomidine (DEX) and medetomidine (MED) at three different dose levels in a randomized, blinded, cross-o ver study. DEX was administered at 25, 50 and 75 mu g/kg (D25, D50 and D75), corresponding to MED 50, 100 and 150 mu g/kg (M50, M100 and M15 0). Sedation, analgesia and muscular relaxation were scored subjective ly. Heart and respiratory rates and rectal temperature were measured. Corresponding doses of DEX and MED were compared. Effects were also co mpared between dose levels for each compound. At dose level 2 (D50-M10 0), the duration of effective clinical sedation was significantly shor ter after DEX (202.5 +/- 16.0 min) than after MED (230.0 +/- 41.2 min) , Proceeding from D50-M100 to D75-M150, the duration of effective clin ical sedation was increased more after DD: (by 57.5 +/- 38.4 min) than after MED (by 14.2 +/- 41.9 min) Increasing from D50-M100 to D75-M150 , heart rate was further decreased after DEX (by 8.1 +/- 13.4%)but not after MED, There was no statistically significant difference between corresponding doses of DEX and MED for any of the other parameters stu died, Changes in sedation, analgesia and muscular relaxation were dose -dependent, It was concluded that anaesthetic effects of medetomidine in cats are probably due entirely to its d-isomer and that dexmedetomi dine at 25, 50 and 75 mu g/kg induces dose-dependent sedation, analges ia and muscular relaxation of clinical significance in cats.