Objective To evaluate spinal (intrathecal) anaesthesia (SA) in addition to general anaesthesia in dogs, and report the incidence of side effects and cardiovascular response (CR) to surgery.
Study design Retrospective clinical study.
Animals One hundred and fifteen dogs undergoing general anaesthesia for surgery caudal to the diaphragm between 2005 and 2008.
Methods Records of anaesthetized dogs that had received SA with bupivacaine or levobupivacaine 0.5%, together with morphine or fentanyl were reviewed. Success rate of SA, complication rate and incidence of CR were recorded and examined in relation to the dose of local anaesthetic administered and the type of surgery. Univariate and Cusum analysis were performed to identify independent predictors of response to surgical stimulation and characterize the learning curve for the technique, respectively.
Results Eighty-two dogs received successful SA. The Cusum plot suggested that a failure rate of 10% is achieved when the procedure is performed more than 66 times. Median local anaesthetic dose related to weight was 0.40 mg kg−1 (0.3–0.5), and to spinal cord length 0.1 mg cm−1 (0.07–0.12). Morphine was added to the local anaesthetic in 56 and fentanyl in 22 dogs. CR post-stimulus occurred in 29 cases: 11 of 22 ovariohysterectomies, 14 of 33 hindlimb-surgeries, 2 of 10 caudal-abdominal-surgeries and 2 of 17 Caesarean sections. Anaesthetic dose related to weight was not a predictor of CR. Bradycardia occurred in seven, hypotension in 24, urinary retention in four and hypersalivation in 6 of 82 dogs.
Conclusions SA was practicable to apply, but in this study did not totally block CR, Side effects were minimal, with an incidence similar to that in humans.
Clinical relevance SA can be used in clinical cases with few side effects although monitoring of and ensuing treatment of hypotension is required. Comparative prospective studies are required to establish efficacy and a reliable dose.