Browsing by Author "Du Plessis, Dianca"

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    The potential of midazolam for use as a sedative for blesbok (Damaliscus pygargus phillipsi)
    (Stellenbosch : Stellenbosch University, 2018-03) Du Plessis, Dianca; Lambrechts, Helet; Hoffman, Louwrens C.; Laubscher, Liesel; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: Wildlife translocation results in stress in the animals, which impacts negatively on their welfare. Midazolam is used as a sedative in domestic species, with minimal cardiopulmonary side effects. Midazolam’s effects in wildlife has not yet been determined. This study aimed to evaluate midazolam as a sedative in blesbok. The first phase of the overall study entailed a pilot study using indigenous goats to determine the pharmacokinetic behavior of midazolam. Blood samples were collected at set time intervals following intramuscular (IM) midazolam administration in the goats. Resulting serum samples were analysed by means of gas chromatography-mass spectrophotometry, and a concentration-time profile of IM midazolam was compiled. Calculation of the pharmacokinetic parameters of midazolam indicated that it took approximately 36 min to reach a maximum serum concentration of 127.3 ng/L. Midazolam had a poor bioavailability and a relatively short elimination half-life. In the second part of the study, the EquivitalTM EQ02 biotelemetry system was validated for use in blesbok. On the first day of the validation study, two blesbok were immobilised, fitted with a biotelemetry belt, and translocated to a laboratory. The heart and respiration rate of each animal were individually recorded for 20 min using the EquivitalTM system, a Cardell® monitor and a manual recording method. The accuracy of the EquivitalTM system in detecting changes in heart and respiration rate caused by adrenaline and Dopram® administration respectively, was also assessed. After 20 min of recording, the animals were returned to the enclosure and the anaesthetic was reversed. The EquivitalTM system remained on the animals for an additional 24 hrs to determine its accuracy in measuring physiological parameters and motion changes of conscious blesbok in captivity. After this 24 hr period, the experimental procedure was repeated. The agreement of the EquivitalTM system with the Cardell® and the manual method for heart rate was moderate to excellent, while the agreement for respiration rate was poor to moderate. The EquivitalTM system was accurate in measuring heart rate and detecting increases in heart rate resulting from adrenaline administration, but failed to accurately measure respiration rate and detect changes caused by Dopram®. The EquivitalTM system successfully measured heart rate and motion changes of conscious blesbok in captivity. In the third part of the study, the effect of three midazolam doses on behaviour, feed intake, heart rate, respiration rate, motion, and level of sedation in blesbok were studied. Four trials were conducted to establish the effect of four different dosages, i.e. a placebo, 0.6 mg midazolam/kg body weight (BWt), 0.4 mg midazolam/kg BWt or 0.2 mg midazolam/kg BWt. After immobilisation, the animals were fitted with the EquivitalTM biotelemetry belts. After reversal of the anaesthetic, the specific dose was administered intramuscularly. Blesbok behaviour was recorded for 12 hrs using a CCTV system. The animals were stimulated and scored for sedation and response to stimulus for the first six hours after midazolam administration. After an observation period of 24 hours, the animals were immobilised, the belts removed and the anaesthetic reversed. To determine the effects of midazolam on feed intake, the feed was weighed at the start of each trial and the end of each trial. Midazolam suppressed vigilance in blesbok. The lowest dose of midazolam decreased walking in blesbok, and increased standing and ruminating behaviour. Heart rate and respiration were decreased by the low dose when the animals were showing vigilance and trotting in alarm. The low dose did not affect heart rate and respiration when the animals were stimulated, but decreased both these parameters when the animals were not stimulated. The medium dose increased standing and ruminating behaviour, while it caused slower heart rate when the animals showed vigilance, trotting in alarm and avoidance. The high dose reduced grooming and agitation, increased walking and reduced standing and ruminating behaviour in blesbok. The high dose elevated the respiration rate of blesbok. Midazolam increased fast motion in stimulated blesbok. The low dose decreased motion in unstimulated blesbok. Midazolam treated via the IM route caused moderate sedation in blesbok. Midazolam decreased the response to stimulus of blesbok. The medium dose caused the least responsiveness to stimulation. Midazolam caused an increase in feed intake in blesbok. In conclusion, a dose of 0.2 mg midazolam/kg BWt was most effective in sedating blesbok without side effects and doses of 0.6 mg midazolam/kg BWt and higher should not be used on its own in blesbok to prevent the occurrence of extrapyramidal effects and severe ataxia. Higher doses of midazolam should rather be used in as adjuvants to anaesthetic immobilisation protocols in wild ungulates, but requires further research.