Success Rate and Perioperative Complications of Lumbosacral Extradural Anaesthesia in Dogs Undergoing Total Hip Replacement: A Double-Centre Retrospective Study.

OBJECTIVE: The aim of this study was to retrospectively evaluate the success rate and perioperative complications of lumbosacral extradural anaesthesia in dogs undergoing total hip replacement. STUDY DESIGN: Records of dogs undergoing total hip replacement in which lumbosacral extradural anaesthesia with 0.5% levo- or bupivacaine combined with either morphine or buprenorphine were retrieved. Success rate was defined as intraoperative fentanyl consumption <1 µg/kg/h with no intravenous infusion of other analgesic drugs and no additional morphine/methadone within the first 3 hours from premedication. Prevalence of intraoperative anaesthetic and postoperative surgical complications was calculated. RESULTS: Overall, 206 dogs were included in the study. Success rate was 88.7%. Hypercapnia (75.2%), hypotension (46.1%), hypothermia (27.7%) and regurgitation (6.3%) were recorded during anaesthesia. Within 24 hours post-surgery, urinary retention (17.8%), vomiting/regurgitation/diarrhea (8.2%) and sciatic neurapraxia of the operated limb (5.8%) were recorded. Luxation of the operated hip occurred at 48 and 72 hours after surgery in two dogs and one dog respectively. One dog had cardiopulmonary arrest at 52 hours after surgery. CONCLUSION: While hypercapnia, hypotension and hypothermia might develop intraoperatively, the high success rate and the relatively low prevalence of postoperative surgical complications directly associated with lumbosacral extradural anaesthesia justify its use in dogs undergoing total hip replacement.

Comparison of two doses of ketamine for induction of anaesthesia in ponies undergoing field castration.

BACKGROUND: Ketamine-based total intravenous anaesthesia techniques are commonly used in equine practice for ponies requiring short procedures such as castration in field conditions. When a longer duration of recumbency than provided by the initial dose of anaesthetic agents is required, administration of supplementary 'top-up' doses of anaesthetic agents is required. Ideally, a single dose of anaesthetic agents would reliably achieve a longer duration of action whilst maintaining adequate anaesthetic, surgical and recovery qualities. AIM: This prospective, randomised and blinded study aimed to compare the UK-licensed induction dose of ketamine with an increased dose in ponies undergoing castration in field conditions. The hypothesis was that an increased dose would produce a longer duration of action without negatively affecting qualities of anaesthesia, surgical conditions and recovery. METHODS: Ponies were randomly allocated to receive ketamine at either 2.2 mg kg-1 (K2.2) or 3 mg kg-1 (K3) combined with diazepam 20 µg kg-1 following pre-anaesthetic medication with romifidine and butorphanol. Quality of anaesthesia, surgery and recovery were scored using simple descriptive scales (SDS) and timings of key events recorded. Top-up doses of ketamine 0.5 mg kg-1 were administered if anaesthesia was inadequate during surgery. Time of top-up doses and total ketamine doses were recorded. Data were analysed using Student t-tests or the Mann-Whitney U test (p < 0.05). RESULTS: Thirty-six ponies completed the study. Six ponies enrolled were excluded due to cryptorchidism or surgical complications that required deviation from the anaesthetic protocol. There were no differences in timing of events recorded, number of ponies requiring top-up ketamine, timing and frequency of top-ups or total ketamine dose. Scores for anaesthetic and recovery qualities, and surgical conditions were similar between groups. CONCLUSION: Both induction doses of ketamine provided a similar duration of action and provided conditions suitable to anaesthetise ponies undergoing castration.

Comparison of ketamine and alfaxalone for induction and maintenance of anaesthesia in ponies undergoing castration.

OBJECTIVE: To compare alfaxalone with ketamine for total intravenous anaesthesia in ponies undergoing castration. STUDY DESIGN: Prospective, randomised, blinded clinical study. ANIMALS: Forty-two, 12-month-old Welsh Mountain ponies. METHODS: Ponies were assigned randomly to receive ketamine or alfaxalone. After administration of romifidine 100 µg kg(-1) and butorphanol 50 µg kg(-1) intravenously (IV), sedation and response to tactile stimulation were scored. If sedation was insufficient, romifidine 30 µg kg(-1) was administered IV. Anaesthesia was induced with ketamine 2.2 mg kg(-1) or alfaxalone 1 mg kg(-1) , both in combination with diazepam 20 µg kg(-1) IV. Time from end of injection to lateral recumbency was recorded. Simple descriptive scores were used to score quality of induction, surgical conditions and recovery. Ketamine 0.5 mg kg(-1) or alfaxalone 0.2 mg kg(-1) were administered if movement was observed. Times to first head lift, sternal recumbency and standing, and number of attempts needed were recorded. All scores were performed by the same observer, unaware of treatment. Normally distributed data were compared using t-test and non-normally distributed data with Mann-Whitney test. Level of significance was set at p<0.05. RESULTS: Three ponies needed additional sedation. Mean induction times were 30 ± 6 and 18 ± 4 seconds following ketamine and alfaxalone respectively (p<0.0001). Additional doses were required by four ponies given ketamine and seven given alfaxalone. Sedation, induction and surgical scores were similar for both groups. Recovery scores (scale of 1-4 with 1 best) differed statistically between groups [ketamine group, median 1 (1-2); alfaxalone group 1.5 (1-4) (p=0.04)]. No differences in anaesthesia time or times taken from end of surgery to head lift, sternal recumbency and standing were detected. CONCLUSION AND CLINICAL RELEVANCE: Induction times following alfaxalone were shorter than following ketamine. Both anaesthetic agents provided acceptable quality of anaesthesia for castration.