Alfaxalone induction dose following administration of medetomidine and butorphanol in the dog.

OBJECTIVE: To determine in dogs the effects of medetomidine and butorphanol, alone and in combination, on the induction dose of alfaxalone and to describe the induction and intubation conditions. STUDY DESIGN: Prospective, randomized, blinded clinical trial. ANIMALS: Eighty-five client-owned dogs (ASA 1 or 2). METHODS: Subjects were block randomized to treatment group according to temperament. The treatment groups were: medetomidine 4 microg kg(-1) (M), butorphanol 0.1 mg kg(-1) (B), or a combination of both (MB), all administered intramuscularly. After 30 minutes, a sedation score was assigned, and alfaxalone 0.5 mg kg(-1) was administered intravenously over 60 seconds by an observer who was unaware of treatment group. Tracheal intubation conditions were assessed and, if tracheal intubation was not possible after 20 seconds, further boluses of 0.2 mg kg(-1) were given every 20 seconds until intubation was achieved. Induction dose and adverse events (sneezing, twitching, paddling, excitement, apnoea and cyanosis) were recorded; induction quality and intubation conditions were scored and recorded. RESULTS: The mean dose of alfaxalone required for induction was similar for groups M and B: 1.2 +/- 0.4 mg kg(-1). The mean dose requirement for group MB (0.8 +/- 0.3 mg kg(-1)) was lower than groups M and B (p < 0.0001). Induction dose was not influenced by temperament or level of sedation. Induction and intubation scores did not differ between treatment groups. Adverse events were noted in 16 dogs; there was no association with treatment group, temperament or level of sedation. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine and butorphanol administered in combination reduce the anaesthetic induction dose of alfaxalone compared to either agent alone. This difference should be taken into account when using this combination of drugs in a clinical setting.

Alfaxalone in cyclodextrin for induction and maintenance of anaesthesia in ponies undergoing field castration.

OBJECTIVE: To evaluate the induction and maintenance of anaesthesia using alfaxalone following pre-anaesthetic medication with romifidine and butorphanol in ponies undergoing castration in the field. STUDY DESIGN: Prospective clinical study. ANIMALS: Seventeen male ponies weighing 169 +/- 29 kg. METHODS: The ponies were sedated with romifidine and butorphanol intravenously (i.v.). Induction time was recorded following administration of alfaxalone 1 mg kg(-1) and diazepam 0.02 mg kg(-1) i.v.. If movement during surgery occurred, alfaxalone 0.2 mg kg(-1) was administered i.v.. The quality of anaesthetic induction, and recovery were scored on a subjective scale of 1 (good) to 5 (poor). The number of attempts to attain sternal recumbency and standing, quality of recovery and times from induction to end of surgery, first head lift, sternal recumbency and standing were recorded. RESULTS: Induction quality was good [median score (range) 1 (1-3)] with a mean +/- SD time of 29 +/- 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 +/- 9 minutes, 31 +/- 9 minutes, 33 +/- 9 minutes and 34 +/- 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1-1) and to attain standing was 1(1-2). Quality of recovery was good, with a recovery score of 1(1-2). CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies.

Bradyarrhythmia in an anaesthetised, elderly, hypertensive cat.

A 14-year-old neutered male domestic shorthaired cat was presented to the University Veterinary Centre Sydney for evaluation and treatment of dental disease. This cat developed an unusual bradyarrhythmia under anaesthesia. The possible causes and treatment of the dysrythmia are discussed.