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Research article - Peer-reviewed, 2021

Intranasal oxygen reverses hypoxaemia in immobilised free-ranging capybaras (Hydrochoerus hydrochaeris)

Cordeiro, Jefferson F.; Sanches, Mariana C.; Rusch, Elidiane; Xavier, Nathalia V.; Cassoli, Ana Angélica; Fahlman, Åsa; Carregaro, Adriano B.


Capybara (Hydrochoerus hydrochaeris) is the main host of tick-borne pathogens causing Brazilian spotted fever; therefore, controlling its population is essential, and this may require chemical restraint. We assessed the impact of chemical restraint protocols on the partial pressure of arterial oxygen (PaO2) and other blood variables in 36 capybaras and the effect of different flows of nasal oxygen (O2) supplementation. The capybaras were hand-injected with dexmedetomidine (5 μg/kg) and midazolam (0.1 mg/kg) and butorphanol (0.2 mg/kg) (DMB, n = 18) or methadone (0.1 mg/kg) (DMM, n = 18). One-third of the animals were maintained in ambient air throughout the procedure, and one-third were administered intranasal 2 L/min O2 after 30 min whereas the other third were administered 5 L/min O2. Arterial blood gases, acid-base status, and electrolytes were assessed 30 and 60 min after drug injection. The DMB and DMM groups did not vary based on any of the evaluated variables. All animals developed hypoxaemia (PaO2 44 [30; 73] mmHg, SaO2 81 [62; 93] %) 30 min before O2 supplementation. Intranasal O2 at 2 L/min improved PaO2 (63 [49; 97] mmHg and SaO2 [92 [85; 98] %), but 9 of 12 capybaras remained hypoxaemic. A higher O2 flow of 5 L/min was efficient in treating hypoxaemia (PaO2 188 [146; 414] mmHg, SaO2 100 [99; 100] %) in all the 12 animals that received it. Both drug protocols induced hypoxaemia, which could be treated with intranasal oxygen supplementation.

Published in

2021, volume: 16, number: 11, article number: e0260441

Authors' information

Cordeiro, Jefferson F.
University of Sao Paulo
Sanches, Mariana C.
University of Sao Paulo
Rusch, Elidiane
University of Sao Paulo
Xavier, Nathalia V.
University of Sao Paulo
Cassoli, Ana Angélica
University of Sao Paulo
Swedish University of Agricultural Sciences, Department of Urban and Rural Development
Carregaro, Adriano B.
University of Sao Paulo

UKÄ Subject classification

Pharmacology and Toxicology

Publication Identifiers


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