Towards total intravenous anaesthesia (TIVA) in goats

Abstract

The objectives of the present series of studies focused on providing information that would improve the literature resource on goat anaesthesia, with more emphasis on total intravenous anaesthesia. Anaesthetic and physiologic effects of total intravenous anaesthesia techniques have been documented in humans, and to some extend in dogs and ponies (Nolan, 2004), but there are very few reports on use of the technique in goats. Findings from a series of studies to evaluate the sedative, anaesthetic and cardiopulmonary effects of different central nervous systems depressants using 6 goats in a randomized crossover design are reported in this thesis. The benzodiazepines such as diazepam and midazolam, the phenothiazines such as acepromazine and some opioids such as butorphanol are among the drugs that are currently used for sedation in goats. In the first study reported in this thesis, midazolam alone, and combinations of butorphanol with acepromazine or midazolam administered intramuscularly reduced the dose of propofol required for induction of general anaesthesia in goats with minimal effects on cardiopulmonary function. Three of the studies reported in this thesis evaluated the effects intravenous administration midazolam, fentanyl and propofol on isoflurane minimum alveolar concentration and cardiovascular function in artificially-ventilated goats. Midazolam, fentanyl and propofol reduced isoflurane minimum alveolar concentration in a dosedependent manner with no adverse effects on cardiovacular function. The last study reported in this thesis evaluated and compared the efficacy of propofol combined with fentanyl, or midazolam for total intravenous anesthesia in goats. The results of last reported study indicate that total intravenous anaesthesia achieved by co-administration of propofol and either fentanyl or midazolam for induction and maintenance of anaesthesia in spontaneously-breathing, oxygen-supplemented goats is satisfactory, although caution must be exercised with the fentanyl-propofol combination as recovery from anaesthesia was rough on some occasions. The findings from the present studies provide specific data on anaesthetic and physiologic effects of several drugs and drug-combinations in anaesthetised goats. The information will be a valuable reference source for general practice veterinarians, veterinary anaesthetists and other biomedical scientists. The information should also help improve general welfare of goats undergoing anaesthetic procedures.