University of Helsinki, Helsinki 2006
Perioperative stress in dogs
Different aspects of manifestation and characteristics with medetomidine and acepromazine preanaesthetic medication
Doctoral dissertation, March 2006.
The series of investigations presented in this thesis examined different aspects of the manifestation of perioperative stress in client-owned dogs and compared the influences of two preanaesthetic medications. Data were obtained from 43 overtly healthy dogs that underwent ovariohysterectomy following preanaesthetic administration of medetomidine and butorphanol (MED) or acepromazine and butorphanol (ACE) (Study 1) and from 96 dogs that were recovering from day-case soft-tissue operations at home (Study 2; data obtained using owner-completed questionnaires).
The results indicated better abilities to attenuate perioperative neurohumoral arousal with MED preanaesthetic administration, but no significant differences were detected for the two treatment groups in the incidence of VPCs or in the inflammatory responses. The different physiological states were especially apparent during the early postoperative recovey, but were not reflected in the simultaneous behavioural observations. Overall, the correlations among the different hormonal measures and among plasma catecholamines and heart rates were weak, but the time-related associations increased in their strength during the early postoperative phase. The indices of efferent cardiac vagal activity showed consistent correlations with the heart rate data and the nonlinear measures of HRV seemed to complement the evaluation of beat-to-beat interval behaviour.
Among hospitalised dogs, signs indicative of preoperative emotional arousal were frequently encountered, but marked differences existed between individual animals with respect to the level of overall activity. Animal's preoperative physiological or behavioural states provided only minor indications of its characteristics at later time points of observation. As reported by animal owners, various aspects of behaviour were altered during the period of postsurgical recovery and the behavioural symptoms were influenced by the type of operation and owner-rated animal pain.
Altogether, the results underline the multi-faceted nature of perioperative stress responses in dogs and the value of using multiple observations for more complete evaluations. The clinical significance of the different effects on perioperative neurohumoral arousal with medetomidine and acepromazine preanaesthetic administration still needs to be determined and better indices to evaluate the characteristics of preoperative arousal are required. Owner-completed observations seem valuable in the assessment of the characteristics of later postsurgical recovery and could be used in future investigations when defining clinically-relevant milestones for postoperative recovery in client-owned dogs.
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© University of Helsinki 2006
Last updated 14.03.2006