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Hyperthermia means an increase in
body temperature above normal range, and an animal is hyperthermic once it's temperature reaches a critical point. The "normal" body temperature range may vary depending upon the method of measurement used. The most widely used method is to take the temperature using a mercury thermometer inserted into the animal's rectum although other orifices can be used (e.g. the vagina). Recently modern technological developments have lead to the use of monitors which are inserted into the external ear canal.

Method for taking body temperature with a mercury thermometer
The rectum should be clear of faeces, and the mercury must be shaken down to the bulb end of the thermometer before inserting it. The thermometer should be held in place for 2 minutes before reading it.

Species variations

Species Normal Critical point


100.9 - 101.7o F ; 38.3 - 38.7o C

105.0oF ; 41.0 o C


100.4 - 101.6o F ; 38.0 - 38.5o C



99.0 - 103.0o F ; 37.0 - 39.4o C



98.0 - 101.0o F ; 36.2 - 37.5o C


Guinea Pig

99.0 - 103.0o F ; 37.2 - 39.5o C



100.5o F ; 38.0o C

102.0o F ; 38.8o C


101.5o F ; 38.5o C

103.0o F ; 39.4o C


102.5o F ; 39.2o C

104.0o F ; 40.0o C


102.0o F ; 38.8o C

103.5o F ; 39.7o C

  • If the temperature exceeds the critical point for the species hyperthermia exists.
  • Body temperature can vary by as much as 2oF (1oF) in many species during the day.


Last updated : October 2013