Measurement System for Body Temperature during
Transition Period of Hibernating Animal
Shigehiro Hashimoto, Akira Nagao, Yusuke Morita,
Tomohiro Sahara, Yuta Morioka
Biomedical Engineering, Dept. of Electronics, Information, and Communication Engineering,Osaka Institute of Technology, Osaka, 535-8585, Japan
hasimoto@elc.oit.ac.jp
andTomohiko Sumita, Hajime Otani, Hiroji Imamura
Dept. of Thoracic and Cardiovascular Surgery, Kansai Medical University
Moriguchi, JapanABSTRACT
A measurement system for body temperature of ahibernating animal has been designed to detect atransition period of hibernation. A Tamias sibiricuswas bred in a cage kept in a refrigerator at four degrees
centigrade. The surface temperature of the squirrel
was measured telemetrically every fifteen minutes witha radiation thermometer. The cage was designed tokeep the animal hibernating in the same place after theperiodic arousal. The measurement system in thepresent study is simple compared with themulti-channel thermography, but effective to detect thetransition period of hibernation.
Keywords: Bio-measurement, Hibernation, Body
temperature, Thermometer, Squirrel

1. INTRODUCTION
During a cardiovascular surgical operation, the heart is
iced and its beating is stopped (Fig. 1). The suspended
period causes harmful effects to the heart after
re-circulation of the blood.
Several kinds of
preconditioning have been applied to protect
myocardial function during the heart surgery [1].
Hibernation is a mysterious period, when every
metabolic level is minimized: the body temperature, theheart rate, and the breathing rate [2].

Surgicaloperation

Suspended period
Iced &stopped

beatingRe-circulation

Fig. 1: Heart surgery.
For designing an animal surgical experiment on blood
circulation during hibernation, it is necessary to detect
whether the condition of the animal is stable [3].
Two periods, "bout” and “periodic arousal", repeat
alternately during hibernation. Each period consistsof a transition period and a stable period (Fig. 2).
Previous studies show that the body temperaturechanges between five and thirty-seven degrees
centigrade during the transition period [2].
The temperature of the body surface has been measured
continuously with a non-invasive method to distinguishhibernation from death and to detect the transition
period of hibernation in the present study.

T37StStSt
Tr

TrTrP5
B

St

St
Tr

P
B

B
Time

Fig. 2: Body temperature (T, centigrade)during hibernation: bout (B), periodic arousal(P), stable period (St), transition period (Tr).

2. METHODSA Tamias sibiricus was bred in a cage kept in arefrigerator at four degrees centigrade (Fig. 3).
The surface temperature of the squirrel was measured
telemetrically (sensor, Keyence, IT2-80; multifunction
data acquisition, National Instruments, SUB-68,
DAQPad -6020E) every fifteen minutes with aradiation thermometer (Figs. 4, 5).
The thermocouple of the radiation thermometer detects
infrared radiation from an object (Fig. 6).

Fig. 4: Telemetric measurement of surface
temperature of the squirrel with radiation
thermometer (upper left): cage (right).

A cage was designed to keep an animal hibernating inthe same place after periodic arousal (Fig. 7).
The space was sectioned into two parts: for sleeping
and evacuating, respectively.
These parts wereconnected with a narrow paths each other. The pile ofwoodchips was limited so that the back of the squirrel
is exposed above the pile during sleep to be targeted forthe measurement of temperature.

Fig. 5: Radiation thermometer sensor (left),
multifunction data acquisition (middle),
computer (right).
Spot
D=40 mm
D=14 mmTC

Fig. 3: Telemetric measurement of surface
temperature of the squirrel in a refrigerator(right): recorder (left).

500 mmThe spot of measurement was stable at the back of thesquirrel during sleep. The tracings show that thesurface temperature is around five degrees centigrade
during bout (Fig. 8). The temperature fluctuates
above ten degrees during periodic arousal, because thesquirrel is moving around and the temperature ofwoodchips in the animal's bed is measured.
The tracings also show that the transition periods ofperiodic arousal and of bout are one hour and 4.5 hours,
respectively, and that the stable period of periodic
arousal continues for 16 hours.

40
35

T

30
25
20
015
10
50-5- 10520

40

60

80

100

120

140

160

180

Fig. 8: Temperature (T, centigrade) tracings.

200

The slope of the tracings shows that the maximum rates
220
240
260
300
320
340
360
384ofchangein 280
surfacetemperatureduringtransition
period of periodic arousal and of bout Timeare 0.5 and 0.2
5 hours
degrees per minute, respectively.
The interval of fifteen-minutes was short enough tomeasure the rate of change in body temperature duringhibernation.

4. DISCUSSION AND CONCLUSION
The design of cage is important, because a squirrel
would kill itself kept in a narrow space. The place forurination should be separated from the bed to prevent
death from cold.

Fig. 7: Cage: space for sleeping (left) andevacuating (right).

3. RESULTS

There are several methods to detect body temperature:
thermograph, recto-thermometer. The measurement
system in the present study is simple compared with themulti-channel thermography, but effective to detect thetransition period of hibernation. With this system, theanimal experiment model would be designed to study
about myocardial protection during the cardiovascularsurgical operation,

5. ACKNOWLEDGMENT
This work was supported in part by a Grant-in-Aid for
Scientific Research from the Japanese Ministry ofEducation, Culture, Sports, Science and Technology.

6. REFERENCES[1] H. Otani, T. Okada, H. Fujiwara, T. Uchiyama, T.
Sumida, M. Kido, H. Imamura. “Combinedpharmacologicalpreconditioning
withaG-protein-coupledreceptor
agonist,amitochondrial KATP channel opener and a nitricoxide donor", Clin Exp Pharmacol Physiol, Vol.
30, 2003, pp. 684-693.
[2] Takeo Kawamichi, Noriaki Kondo, and Tetuo
Morita. The mammals which hibernate. Tokyo:
University of Tokyo Press, 2000.
[3] Hajime Otani. “Hibernation triggers andmyocardial protection: Editorial comment”,
Circulation 98, 1998, pp. 2-223-2-224.