The big sleep - phys.org

1 The big sleep3 July 2012 All zoo animals - and sometimes also wild animals- occasionally need veterinary treatment andanaesthesia is clearly required in many cases. Formost animals the procedures are well establishedbut for a variety of reasons it has proven difficultyto anaesthetize hippopotamuses. The thick skinand the dense subcutaneous tissue make it difficultto introduce sufficient amounts of anaesthetics andopioid-based anaesthetics often cause breathingirregularities and occasionally even death. Inaddition, the level of anaesthesia is only rarelysufficient to enable surgery to be undertaken: fewvets wish to be around when a druggedhippopotamus starts to wake up. Together with Thierry Petit from the Zoo de laPalmyre, France, and collaborators in Germanyand Israel, Gabrielle Stalder and Chris Walzer fromthe Research Institute of Wildlife Ecology,University of Veterinary Medicine, Vienna(Vetmeduni Vienna) have now developed a newanaesthetic protocol based on the use of two non-opiate drugs, medetomidine and ketamine.

2 Theprocedure has been tested on a total of ten captivehippopotamuses, all of which were successfullyanaesthetized to an extent that enabled surgery -although due to the difficulty to estimate their exactweight some animals needed additional doses ofanaesthetic before they could be safely , all animals recovered rapidly andcompletely from the procedure and showed nolasting during anesthesia?This does not mean that the anaesthesia alwayspassed without incident: five of the ten animalsstopped breathing for periods of up to nearly tenminutes. But in each case the hippopotamusspontaneously recommenced breathing without theneed for any intervention. The Vetmed scientistsinterpret the temporary suspension of breathing asa dive response: their aquatic lifestyle means thathippopotamuses are able to hold their breath forrelatively long periods, so it is likely that theanimals also "dived" during the period researchers thus had a unique opportunity tolearn what happens when hippopotamuses stopbreathing.

3 The level of oxygen in the blood naturallydecreases but this is not associated with anincrease in heart rate nor, surprisingly, withincreased levels of lactate. As Walzer says, "alldiving mammals have evolved a strategy to copewith the shortage of oxygen while they areunderwater. The reaction of hippopotamuses toanaesthesia suggests that they do not switch toanaerobic metabolism when they dive but possiblyhave other mechanisms to help them use theoxygen in their blood more efficiently. The hoodedseal is known to have very high levels of myoglobinin its muscles: maybe the hippopotamus has asimilar trick to help it survive?" More information: The paper "Use of amedetomidine-ketamine combination for anesthesiain captive common hippopotami (Hippopotamusamphibius)" by Gabrielle L. Stalder, Thierry Petit,Igal Horowitz, Robert Hermes, Joseph Saragusty,Felix Knauer and Chris Walzer is published in theJuly 1, 2012 issue of the Journal of the AmericanVeterinary Medical Association (Vol.)

4 241, No. 1,Pages 110-116).Abstract of the scientific article online: ..2460 Provided by University of Veterinary Medicine --Vienna 1 / 2 APA citation: The big sleep (2012, July 3) retrieved 9 October 2019 from document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, nopart may be reproduced without the written permission. The content is provided for information purposes by TCPDF ( ) 2 / 2