The optimal dose of medetomidine-ketamine-buprenorphine was determined in 25 Cape ground squirrels (Xerus inauris) undergoing surgical implantation of a temperature logger
into the abdominal cavity. At the end of anaesthesia, the squirrels were given atipamezole intramuscularly to reverse the effects of medetomidine. The mean dose of medetomidine
was 67.6±9.2 μg/kg, ketamine 13.6±1.9 mg/kg and buprenorphine 0.5±0.06 μg/kg. Induction time was 3.1 ± 1.4 min. This produced surgical anaesthesia for 21± 4.2 min.
Atipamezole 232±92 μg/kg produced a rapid recovery. Squirrels were sternally recumbent in 3.5 ± 2.2 min.http://www.journals.co.za/ej/ejour_savet.htm

Bateman, Philip W.

Bennett, Nigel C., 1961-

Joubert, Kenneth E.

Manjerovic, Mary-Beth

Scantlebury, Michael

Serfontein, Tania

Waterman, Jane M.

Bennett, Nigel Charles

UPSpace at the University of Pretoria

Article — ArtikelDetermination of an optimal dose of medetomidine-ketamine-buprenorphinefor anaesthesia in the Cape ground squirrel (Xerus inauris)K E Jouberta*, T Serfonteinb, M Scantleburyc,d, M B Manjerovice, P W Batemand,N C Bennettd and J M WatermanfINTRODUCTIONThe Cape ground squirrel (Xerusinauris) inhabits hot and arid areas ofsouthern Africa. Ground squirrels havebeen suggested to use both behaviouraland physiological means to adapt to theextremes of temperature they encounter.For example, they may use their tail as aparasol to reduce solar radiation1 orretreat to cool burrows as a thermal ref-uge during the day6 in order to regulatebody temperature (Tb). The present studyutilised 2 populations of squirrels, 1 froman open plain with little or no shade anda 2nd population from a location sur-rounded by shady thorn trees. The reasonfor anaesthetising the squirrels was toimplant miniature temperature loggers(iButtons® DS1922L ± 0.0625 °C; Thermo-chron, Dallas Semiconductors, MaximIntegrated Products, Inc., Sunnyvale, CA)into the abdomen of the squirrels to moni-tor Tb and relate this to environmentaland behavioural data. The anaesthetic re-quirements for this project were a rapidinduction, sufficient anaesthetic durationto complete implantation of the loggersand a rapid recovery before being re-turned to their colonies. The surgery andanaesthesia were performed in the fieldwhere minimal equipment was available.Ketamine has been used for the immo-bilisation of the Cape ground squirrel18.High doses of ketamine (40–50 mg/kg)were required for complete immobilisationof the squirrels18. No recovery times wererecorded18. In Richardson’s ground squir-rel (Spermophilus richardsonii), ketamine at86 mg/kg, droperidol (2.6 mg/kg) andfentanyl (52 µg/kg), and pentobarbitone(50 mg/kg) failed to produce surgicalanaesthesia15. Xylazine (10 mg/kg) andketamine (85 mg/kg) administered eithersubcutaneously or intramuscularly pro-duced surgical anaesthesia in Richard-son’s ground squirrel15. Medetomidine-ketamine anaesthesia has been success-fully used for the induction of anaesthesiain dogs7,8,11,12,14,16,20, cats17, mice5, horses2 andwildlife (impala and badgers)3,13. Mede-tomidine-ketamine has been shown toproduce a rapid induction, provide ade-quate analgesia for surgery and a rapidrecovery when reversed with atipa-mezole. On this basis medetomidine-ketamine was selected for anaesthesia.Antagonism of medetomidine generallyresults in reversal of the analgesic effects.For this reason, buprenorphine was ad-ministered for post-operative analgesia.MATERIALS AND METHODSTwenty-five squirrels from the SALombard Nature Reserve (3660 ha, 18 kmnorthwest of Bloemhof, South Africa,27°35’S, 25°23’E) were captured in Toma-hawk wire-mesh traps (15 × 15 × 50 cm)as previously described9,18. Thirteen malesand 12 females were captured. Theirmean weight was 625.2 ± 70.2 g (males632.2 ± 84.9 g, females 618.8 ± 52.7 g).Females and resident males were trappedfor implantation of temperature loggers.Five migratory males were caught. Thesemales were anaesthetised for the place-ment of radio-collars (1), body measure-ments (1) and collection of semen (3) andtheir data were excluded from analysis.An initial dose of medetomidine (Domitor,Pfizer Animal Health) of 0.03 m(50 µg/kg) and ketamine (Anaket V,Centaur Laboratories, Isando) of 0.075(15 mg/kg) was chosen. If anaesthesia wasunsuccessful the doses of medetomidineand ketamine were increased by 0.01 mand 0.025 m , respectively until appropriateanaesthetic levels were achieved. Themedetomidine and ketamine were admin-istered in the same insulin syringe (1 mBD U-100 Insulin Syringe, Manta Medical,Bryanston). Buprenorphine (Temgesic,Schering Plough, Isando) was adminis-tered at a standard dose of 0.1 m persquirrel in a separate insulin syringe. Allinjections were given intramuscularlyinto the lumbar epaxial muscles. Follow-ing induction of anaesthesia, the abdo-men was shaved and prepared forsurgery following standard aseptic tech-niques. During preparation potassiumclavulanate and amoxicillin trihydrate(Synulox RTU, Pfizer Animal Health)(20 mg/kg) was administered subcutane-ously. An incision approximately 15 mmin length was made in the ventral midlinebetween the xiphoid and the umbilicalscar. The temperature logger was then94 0038-2809 Tydskr.S.Afr.vet.Ver. (2011) 82(2): 94–96aPharmacology, Department of Paraclinical Studies,Faculty of Veterinary Science, University of Pretoria,Private Bag X04, Onderstepoort, 0110 South Africa.bAnaesthesiology, Onderstepoort Academic VeterinaryHospital, Faculty of Veterinary Science, University ofPretoria, Private Bag X04, Onderstepoort, 0110 SouthAfrica.cSchool of Biological Sciences, Queen’s UniversityBelfast, Belfast BT9 7BL, UK.dDepartment of Zoology and Entomology, University ofPretoria, Pretoria 0002, South Africa.eDepartment of Biology, University of Central Florida,Orlando, FL 32816-2368, USA.fDepartment of Biological Sciences, University ofManitoba, Winnipeg, MB R3T 2N2, Canada.*Author for correspondence. Present address: PO Box1898, Lonehill, 2062 South Africa.E-mail: hypnyx@wbs.co.zaReceived: June 2010. Accepted: May 2011.ABSTRACTThe optimal dose of medetomidine-ketamine-buprenorphine was determined in 25 Capeground squirrels (Xerus inauris) undergoing surgical implantation of a temperature loggerinto the abdominal cavity. At the end of anaesthesia, the squirrels were given atipamezoleintramuscularly to reverse the effects of medetomidine. The mean dose of medetomidinewas 67.6 ± 9.2 µg/kg, ketamine 13.6 ± 1.9 mg/kg and buprenorphine 0.5 ± 0.06 µg/kg. Induc-tion time was 3.1 ± 1.4 min. This produced surgical anaesthesia for 21± 4.2 min.Atipamezole 232 ± 92 µg/kg produced a rapid recovery. Squirrels were sternally recumbentin 3.5 ± 2.2 min.Keywords: anaesthesia, atipamezole, buprenorphine, Cape ground squirrel, ketamine,,medetomidine, Xerus inauris.Joubert K E, Serfontein T, Scantlebury M, Manjerovic M B, Bateman P W, Bennett N C,Waterman J M Determination of an optimal dose of medetomidine-ketamine-buprenorphine for anaesthesia in the Cape ground squirrel (Xerus inauris). Journal of theSouth African Veterinary Association (2011) 82(2): 94–96 (En.). Pharmacology, Department ofParaclinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04,Onderstepoort, 0110 South Africa.inserted into the abdomen. The linea albawas closed with 4/0 Nylon (Ethicon, John-son & Johnson, Midrand) and the subcu-taneous tissue and skin with 4/0 PDS(Ethicon, Johnson & Johnson) in a stan-dard fashion. The squirrels’ heart rate andrespiration were monitored using amultiparameter physiological monitor(Dash 4000, GE Electronics, Midrand)following standard anaesthetic proce-dures for patient safety. The data are notpresented. The anaesthesia was reversedwith a volume of atipamezole (Antisedan,Pfizer Animal Health) equal to the totalvolume of medetomidine administeredfor immobilisation. Squirrels used forsemen collection, measurement and radiotransmitter placement did not receivebuprenorphine.The time from injection of medetomi-dine-ketamine and buprenorphine untilloss of response to a paw pinch (inductiontime), the duration of anaesthesia (induc-tion to recovery), the duration of surgery,the time from induction to the injection ofatipamezole (anaesthetic time) and thetime to return of the righting reflex fol-lowing the administration of atipamezole(recovery time) were recorded. Any ad-verse anaesthetic or surgical events wererecorded.Descriptive statistics were used todescribe the data collected. Data werenormally distributed. A t-test was used toexamine differences between males andfemales with respect to the followingvariables: weight, induction time, dura-tion of surgery, recovery time, anaesthetictime and doses of drugs administeredper kg. Statistical significance was set atP < 0.05. This study was approved by theAnimal Use and Care Committee of theUniversities of Central Florida andPretoria and complied with their guide-lines for animal research (UCF IACUC#07-43W).RESULTSThe male and female groups were notstatistically different with respect to weight,induction time, duration of surgery,recovery time, anaesthetic time and dosesof drugs administered per kg and theirdata were analysed together. Data for all25 squirrels are presented in Table 1. Thereason for excluding some data is thatbuprenorphine was not administered, nosurgery was performed and the durationof anaesthesia was variable. Temperatureloggers were implanted into 20 squirrels(8 males, 12 females). The 1st squirrel wasexcluded from analysis as the dose ofdrugs administered was insufficient tocomplete the surgery. The doses ofmedetomidine and ketamine were in-creased after this squirrel. This left 190038-2809 Jl S.Afr.vet.Ass. (2011) 82(2): 94–96 95Table1:Datacollectedfromthesquirrelsincludeweight,sex,dosesofdrugsadministeredandtimes.N/Rindicatesthedatawerenotrecorded.SquirrelWeightSexMedetomidineKetamineBuprenorphineInductiontimeAnaesthetictimeSurgerytimeAtipamezoleRecoverytimeProcedureCommentsno.(g)(µg/kg)(mg/kg)(µg/kg)(min)(min)(min)(µg/kg)(min)2580Female68.9717.2451.72516N/R344.8311CeliotomyDiscordantrecovery3660Female60.6112.1245.455148303.034Celiotomy4600Male66.6713.3350.002169333.333Celiotomy5620Female64.5212.9048.3932211322.582Celiotomy6700Male85.7114.2942.8642310428.574Celiotomy8600Female66.6713.3350.002.51610333.333Celiotomy9605Female66.1213.2249.594228330.583Celiotomy10620Female64.5212.9048.3922310161.291Celiotomy11650Female61.5412.3146.1561910153.853Celiotomy14560Female71.4314.2953.5722311178.575Celiotomy16515Female77.6715.5358.252258194.175Celiotomy17660Male60.6112.1245.4512112151.521Celiotomy18450Male88.8917.7866.6752110222.225Celiotomy19680Male58.8211.7644.12320N/R147.063Celiotomy&collar20640Male62.5012.5046.8823010156.251Celiotomy21710Female56.3411.2742.252258140.853Celiotomy23500Male80.0016.0060.003286200.002Celiotomy24675Female59.2611.8544.442187148.154Celiotomy25630Female63.4912.7047.6241913158.733CeliotomyMean613.4267.6013.5549.573.1321.119.47232.053.47S.D.68.909.211.866.291.394.201.8191.752.22Median62064.5212.948.393.0021.0010.00194.173.00Squirrelsexcludedfromthestudy1570Male52.6313.1652.6315263.165CeliotomyNotcompletelyanaesthetised12725Male82.7611.030.00130n/a206.905Ejaculation22635Male62.999.450.00515n/a157.485Collar15750Male80.0013.330.00225n/a200.005Measurements7635Male62.999.450.001.240n/a314.96N/REjaculation13660Male60.619.090.00235n/a151.527Ejaculation96 0038-2809 Tydskr.S.Afr.vet.Ver. (2011) 82(2): 94–96squirrels (7 males, 12 females) in whichthe procedure was successfully com-pleted with the initial doses adminis-tered. The mean dose of medetomidinewas 67.6 ± 9.2 µg/kg, ketamine 13.6 ±1.9 mg/kg and buprenorphine 0.5 ±0.06 µg/kg. Squirrel no. 2 had a roughrecovery characterised by excitement andthe dose of ketamine was reduced forthe following squirrels by 5 mg/kg. Theremaining 18 squirrels were successfullymanaged with the combination describedand had satisfactory recoveries.DISCUSSIONThis study showed that a combinationof medetomidine, ketamine andbuprenorphine provided rapid surgicalanaesthesia that was rapidly reversed atthe end of the procedure with atipamezole.Ketamine alone does not completely im-mobilise Cape ground squirrels at dosesbetween 10 and 25 mg/kg while doses of40–50 mg/kg are required for completeimmobilisation18. In the Richardson’sground squirrel, 86 mg/kg of ketaminealone did not produce surgical anaesthe-sia15. The combination of xylazine andketamine did produce surgical anaesthesiaof 20–30 min duration15. This duration ofanaesthesia would be sufficient to allowfor the implantation of temperature log-gers15. Medetomidine was chosen overxylazine due to greater potency, morespecific affinity for alpha2 receptors andits safety when used in wild animals incombination with ketamine4,10,19.The induction time for xylazine-keta-mine was 1.3 min15 compared with the3.1 min in our study. The longer durationfor induction observed in the presentstudy is most probably due to the lowerdose of ketamine used, 86 mg/kg15 com-pared with 13.6 mg/kg. The squirrelscould be handled within a minute ofadministration of the immobilising drugsintramuscularly (loss of righting reflex)but would be responsive to pain stimuli.The present study’s induction time was tothe point of not responding to painfulstimuli (paw pinch reflex). Handling ofthe immobilised squirrels was possiblebefore the end of the induction time. Inthe present study squirrels were onlyhandled once they were anaesthetised.Recovery times (3.5 min) observed inthe present study were faster thanthose reported for xylazine-ketamine(16–19 min)15. This is most probably theresult of administration of an antagonistat the end of the procedure. With theexception of squirrel number 2, all recov-eries were smooth and uneventful. It wasthought that the rough recovery in squir-rel number 2 could have been due tothe residual effects of ketamine after thereversal of the medetomidine.The combination of medetomidine,ketamine and buprenorphine producedsatisfactory anaesthesia for 20 min andrecovery from anaesthesia was rapidfollowing the administration of atipame-zole in Cape ground squirrels. This com-bination produced an adequate depth ofanaesthesia for surgery.REFERENCES1. Bennett A F, Huey R B, John-Alder H, NagyK A 1984 The parasol tail and thermo-regulatory behaviour of the Cape groundsquirrel Xerus inauris. Physiological Zoology57: 57–622. 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Determination of an optimal dose of medetomidine-ketamine-buprenorphine for anaesthesia in the Cape ground squirrel (Xerus inauris)

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Determination of an optimal dose of medetomidine-ketamine-buprenorphine for anaesthesia in the Cape ground squirrel (Xerus inauris)

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