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  • Author or Editor: Misse Väisänen x
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Abstract

Objective—To compare 3 dose levels of medetomidine and dexmedetomidine for use as premedicants in dogs undergoing propofol-isoflurane anesthesia.

Animals—6 healthy Beagles.

Procedure—Dogs received medetomidine or dexmedetomidine intravenously at the following dose levels: 0.4 µg of medetomidine or 0.2 µg of dexmedetomidine/kg of body weight (M0.4/D0.2), 4.0 µg of medetomidine or 2.0 µg of dexmedetomidine/ kg (M4/D2), and 40 µg of medetomidine or 20 µg of dexmedetomidine/kg (M40/D20). Sedation and analgesia were scored before induction. Anesthesia was induced with propofol and maintained with isoflurane. End-tidal isoflurane concentration, heart rate, and arterial blood pressures and gases were measured.

Results—Degrees of sedation and analgesia were significantly affected by dose level but not drug. Combined mean end-tidal isoflurane concentration for all dose levels was higher in dogs that received medetomidine, compared with dexmedetomidine. Recovery time was significantly prolonged in dogs treated at the M40/D20 dose level, compared with the other dose levels. After induction, blood pressure decreased below reference range and heart rate increased in dogs treated at the M0.4/D0.2 dose level, whereas blood pressure was preserved in dogs treated at the M40/D20 dose level. However, dogs in these latter groups developed profound bradycardia and mild metabolic acidosis during anesthesia. Treatment at the M4/D2 dose level resulted in more stable cardiovascular effects, compared with the other dose levels. In addition, PaCO2 was similar among dose levels.

Conclusions and Clinical Relevance—Dexmedetomidine is at least as safe and effective as medetomidine for use as a premedicant in dogs undergoing propofol-isoflurane anesthesia. (Am J Vet Res 2001;62:1073–1080)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To identify behavioral alterations in client-owned cats recovering at home following elective ovariohysterectomy or castration and determine owner perceptions regarding severity of postoperative pain.

Design—Cohort study.

Animals—145 cats undergoing elective ovariohysterectomy (n = 80) or castration (65) at 4 veterinary clinics in Finland.

Procedures—Owners were asked to complete a questionnaire on their cats' behavior during the 3 days after surgery. Owners were also asked to indicate their perceptions of the severity of postoperative pain during these days by use of a 100-mm visual analog scale.

Results—Owners consistently indicated that there were changes in their cats' behavior, with the most commonly reported alterations being a decrease in overall activity level, an increase in the amount of time spent sleeping, a decrease in playfulness, and altered way of movement. Changes (ie, either an increase or decrease) in aggressive behavior were rare. Median pain score the day of surgery was 15.0 mm for male cats and 25.0 mm for female cats. Behavior score was significantly associated with day of observation, type of surgery (ovariohysterectomy vs castration), owner-assigned pain score, and veterinary clinic.

Conclusions and Clinical Relevance—Results suggested that behavioral alterations can be detected for several days after surgery in cats recovering at home following ovariohysterectomy or castration and emphasized owner concerns about the existence of postoperative pain.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication.

Animals—42 client-owned dogs that underwent elective ovariohysterectomy.

Procedure—Each dog was randomly allocated to receive medetomidine and butorphanol tartrate (20 µg/kg and 0.2 mg/kg, respectively, IM) or acepromazine maleate and butorphanol (0.05 and 0.2 mg/kg, respectively, IM) for preanesthetic medication. Approximately 80 minutes later, anesthesia was induced by administration of propofol and maintained by use of isoflurane in oxygen. Each dog was also given carprofen before surgery and buprenorphine after surgery. Plasma concentrations of epinephrine, norepinephrine, cortisol, and β-endorphin were measured at various stages during the perioperative period. In addition, cardiovascular and clinical variables were monitored.

Results—Concentrations of epinephrine, norepinephrine, and cortisol were significantly lower for dogs administered medetomidine. Concentrations of β-endorphin did not differ between the 2 groups. Heart rate was significantly lower and mean arterial blood pressure significantly higher in dogs administered medetomidine, compared with values for dogs administered acepromazine.

Conclusions and Clinical Relevance—Results indicate that for preanesthetic medications, medetomidine may offer some advantages over acepromazine with respect to the ability to decrease perioperative concentrations of stress-related hormones. In particular, the ability to provide stable plasma catecholamine concentrations may help to attenuate perioperative activation of the sympathetic nervous system. (Am J Vet Res 2002;63:969–975)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate heart rate characteristics in dogs undergoing ovariohysterectomy following premedication with medetomidine or acepromazine.

Design—Clinical trial.

Animals—43 client-owned dogs.

Procedure—24-hour ambulatory electrocardiography was performed beginning approximately 1 hour prior to administration of premedications. Dogs were premedicated with medetomidine and butorphanol (n = 21) or acepromazine and butorphanol (22) and, approximately 85 minutes later, were anesthetized with propofol and isoflurane. Electrocardiographic recordings were examined to determine heart rate, cardiac conduction disturbances (ventricular premature complexes and atrioventricular block), and indices of heart rate variability (HRV).

Results—Minimum heart rate during the 24-hour recording period was significantly lower among dogs given medetomidine than among dogs given acepromazine, but during the postoperative period, heart rate increased in all dogs as they became physically active. Intraoperative time domain HRV indices were lower and the low frequency-to-high frequency ratio was higher among dogs given acepromazine than among dogs given medetomidine; however, significant differences between groups were no longer seen by 6 hours after surgery. There was no significant difference between groups with regard to the number of ventricular premature complexes or to values of scaling exponent α2 (a nonlinear measure of HRV).

Conclusions and Clinical Relevance—Results suggest that there are greater enhancements in vagally related heart rate indices in medetomidine-treated dogs that may persist until 6 hours after surgery. Despite the low heart rates, dogs given medetomidine showed expected responses to surgery and positional stimuli, and the 2 preanesthetic protocols may not result in different prevalences of ventricular premature complexes. (J Am Vet Med Assoc 2005;226:738–745)

Full access
in Journal of the American Veterinary Medical Association