Serial Temperature Monitoring and Comparison of Rectal and Muscle Temperatures in Immobilized Free-Ranging Black Rhinoceros (Diceros bicornis)

Abstract

Control of body temperature is critical to a successful anesthetic outcome, particularly during field immobilization of wild animals. Hyperthermia associated with exertion can lead to serious and potentially life-threatening complications such as organ damage (including myopathy) and death. Methods for monitoring core body temperature must accurately reflect the physiologic status of the animal in order for interventions to be effective. The goal of this preliminary study was to compare serial rectal and muscle temperatures in field-immobilized black rhinoceros (Diceros bicornis) and evaluate a possible association. Twenty-four free-ranging black rhinoceros were immobilized between February and March of 2010 in Ethosha National Park, Namibia. Pairwise comparisons showed a correlation of 0.73 (95% CI; 0.70-0.75) between rectal and muscle temperature measurements. Results from a multivariable model indicate that muscle temperature readings were, on average, 0.46 degrees C (95% CI; 0.36-0.57 degrees C) higher than rectal temperatures while adjusting for repeated measurements on the same rhinoceros, effect of duration of immobilization, and effect of ambient temperature on rhinoceroses' temperature readings. As immobilization time increased, muscle and rectal temperature values within an individual rhinoceros tended to equilibrate. The overall temperatures decreased by an average of 0.00059 degrees C/min (95% CI; -0.0047 to -0.0035 degrees C/min; P = 0.779). As the ambient temperature at time of immobilization increased by 1 degree C, the average rhinoceros temperature increased by 0.09 degrees C (95% CI; 0.06-0.11 degrees C, P < 0.0001). Higher body temperature creates a potential for cellular damage leading to complications that include myopathy. Methods for monitoring rectal, muscle, and ambient temperatures should be incorporated into anesthetic monitoring protocols for large ungulates, particularly under field conditions.

Challenges of measuring body temperatures of free-ranging birds and mammals

“…This fast, affordable, and minimally invasive method relies on inserting a thin temperaturesensitive probe into the rectum via the anus or cloaca [20][21][22]. It is commonly undertaken using thermocouples or thermistors either custom adapted for use or using standard medical or veterinary thermometers.…”

Microchip transponder thermometry for monitoring core body temperature of antelope during capture

“…Whether muscle temperatures measured with microchips are appropriate for accurately monitoring capture-induced hyperthermia in other mammals, especially larger species, remains to be confirmed. Gluteal muscle temperature has been shown to be suitable for monitoring body temperature during capture and immobilization in black rhino (Morkel et al 2012). Therefore, intramuscularly implanted microchips should be effective for this purpose in rhinoceros.…”

“…Rectal temperature measurement also varies with probe position in the rectum, and requires placement for a few minutes to allow for probe temperature to stabilize (Mitchell and Laburn, 1985). Improving the ability to monitor core body temperature accurately and conveniently in wild animals during capture is essential for their well-being (Morkel et al, 2012;Ozeki et al, 2014).…”

Intraskeletal variability in phosphate oxygen isotope composition reveals regional heterothermies in marine vertebrates

“…On the other hand, some poikilotherms are able to produce heat locally (Carey, 1982;Block, 1986;Dickson and Graham, 2004) to improve visual acuity in cold environment (Block, 1987;Fritsches et al, 2005), swim faster or migrate longer distances (Bernal et al, 2001;Blank et al, 2007;Watanabe et al, 2015). These two strategies lead to temperature heterogeneities called regional heterothermies which can be measured on extant organisms thanks to thermometer reading (Ponganis et al, 2003;Morkel et al, 2012) and thermal imagery (Hampton et al, 1971;Tattersall et al, 2009). However, such methods suffer from several types of limitation.…”