Comparison of two protocols for field immobilization of white-eared opossums (Didelphis albiventris)

  • Samanta WaxmanEmail author
  • Marcela Orozco
  • Hernán Argibay
  • Casilda Rodriguez
  • Pablo Otero
Short Communication


The aim of this study was to investigate the efficacy of two protocols for field immobilization of white-eared opossums (Didelphis albiventris) and compare their effects on immobilization, cardiopulmonary variables, and recovery times. Twenty one opossums were randomly divided into two groups; G1 received ketamine (15 mg kg−1)-dexmedetomidine (0.15 mg kg−1) intramuscularly (IM) and G2 received the ketamine-dexmedetomidine combination and isoflurane once induction was achieved. Oxygen was delivered by face mask (1.5 L minute−1). Thirty minutes after induction, isoflurane was discontinued (G2) and both groups were administered atipamezole (1.5 mg kg−1) IM. Respiratory (ƒR) and heart rate (HR), oxyhemoglobin saturation (SpO2), and rectal temperature (T) were recorded every 5 min. Induction time, time to first movement (RT1), and time to achieve standing (RT2) were recorded. ANOVA and non-parametric tests were used. Level of immobilization was assessed by observation of movements and evaluation of muscle relaxation. The mean induction time was 4.71 min. RT1 and RT2 were significantly longer in G2. No significant differences were found in SpO2 or ƒR. HR did not vary significantly along time, but was higher in G2. Rectal temperature did not show differences between treatments, but decreased significantly with time in G2. Four of nine animals in G1 showed movements, while no animals in G2 did and muscle relaxation was determined to be better in this latter group. Both protocols were adequate for short-term field immobilization, with minimal alterations of HR and T and relatively short recovery times. Isoflurane provided better immobilization with statistically significant prolongation of recovery times.


Ketamine Dexmedetomidine Isoflurane Field immobilization Opossum 



The authors wish to thank Flavia Netto, Tomas Franzese, Esteban Actis, and Yanina Berra for field assistance; Dr. Ricardo Gürtler and the Ecoepidemiology Lab for institutional assistance; and Dr. Miguel Angel Rinas and the staff of Parque Ecológico El Puma, Ministry of Ecology and Natural Resources of Misiones.


This study was performed as part of an UBACyT project, supported by the University of Buenos Aires. Other sources of founding: a grant from Roemmers Foundation (Hernán Argibay), Consejo Nacional de Investigaciones Científicas y Técnicas (PIP 2012-2015), Agencia Nacional de Promoción Científica y Tecnológica (PICT 2011-2072, PICTO-Glaxo 2011-0062) (Projects directed by Dr. Ricardo Gürtler).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest

Ethical approval

All procedures performed involving animals were in accordance with the ethical standards of the Institution (Veterinary Sciences School, University of Buenos Aires) and were approved by its Institutional Animal Care and Use Committee (protocol no. 2012/36).


  1. Argibay HD, Orozco MM, Cardinal MV et al (2016) First finding of Trypanosoma cruzi II in vampire bats from a district free of domestic vector-borne transmission in Northeastern Argentina. Parasitology 25:1–11Google Scholar
  2. Chinnadurai SK, Strahl-Heldereth D, Fiorello CV et al (2016) Best practice guidelines for field-based surgery and anesthesia of free-ranging wildlife. I. Anesthesia and analgesia. J Wildl Dis 52:S14–S27CrossRefPubMedGoogle Scholar
  3. Kimble DP (1997) Didelphid behavior. Neurosci Biobehav Rev 21:361–369CrossRefPubMedGoogle Scholar
  4. Kocer CJ, Powell LA (2009) A field system for isoflurane anesthesia of multiple species of mesopredators. Am Midl Nat 161:406–412CrossRefGoogle Scholar
  5. Orozco MM, Enriquez GF, Alvarado-Otegui JA et al (2013) New sylvatic hosts of Trypanosoma cruzi and their reservoir competence in the humid Chaco of Argentina: a longitudinal study. Am J Trop Med Hyg 88:872–882CrossRefPubMedPubMedCentralGoogle Scholar
  6. Steffey EP, Mama KR, Brosnan RJ (2015) Inhalation anesthetics. In: Grimm KA, Lamont LA, Tranquilli WJ et al (eds) Veterinary anesthesia and analgesia, 5th edn. Wiley Blackwell, UK, pp 297–331Google Scholar
  7. Stoskopf MK, Meyer RE, Jones M, Baumbarger DO (1999) Field immobilization and eutanasia of american opossum. J Wildl Dis 35:145–149CrossRefPubMedGoogle Scholar
  8. Tarragona EL, Zurvera D, Manzoli DE et al (2014) Chemical immobilization and physiological evaluation of wild white eared opossums, Didelphis albiventris (Lund 1841) of Santa Fe province, Argentina. InVet 16:79–85Google Scholar
  9. Viggers KL, Lindenmayer DB (1995) The use of tiletamine hydrochloride and zolazepam hydrochloride for sedation of the mountain brushtail possum, Trichosurus caninus Ogilby (Phalangeridae: Marsupialia). Aust Vet J 72:215–216CrossRefPubMedGoogle Scholar
  10. Xiong J, Kurz A, Sessler D et al (1996) Isoflurane produced marked and nonlinear decreases in the vasoconstriction and shivering thresholds. Anesthesiology 85:240–245CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Facultad de Ciencias Veterinarias, Cátedra de Anestesiología y AlgiologíaUniversidad de Buenos AiresBuenos AiresArgentina
  2. 2.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Buenos AiresArgentina
  3. 3.Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Facultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
  4. 4.Facultad de VeterinariaUniversidad Complutense de MadridMadridSpain

Personalised recommendations