A Device that Allows Rodents to Behaviorally Thermoregulate when Housed in Vivariums
Citation:
Gordon, C., E. Puckett, E. Repasky, AND A. Johnstone. A Device that Allows Rodents to Behaviorally Thermoregulate when Housed in Vivariums. Journal of the American Association for Laboratory Animal Science. American Association for Laboratory Animal Science, Memphis, TN, 56(2):173-176, (2017).
Impact/Purpose:
Mice and rats housed in standard vivariums and under typical laboratory conditions maintained at a room temperature of 22 ⁰C are generally cold stressed. In addition, when exposed in air pollution chambers, rodents may often become hypothermia due to the combined effects of the pollutant and relatively cool temperatures of the chamber, a response that can compromise data variability and animal well-being. In this methods study, a simple device was developed that allows mice to use their natural behavioral thermoregulatory reflexes to move into a warmed, enrichment-type device and allows the animals to achieve a long-term state of thermal comfort. This prototype can be adapted to be used in air pollution systems and alleviated potential hypothermic responses.
Description:
Laboratories and vivariums are maintained at ambient temperatures (Ta) of 20-24 ⁰C and it is widely accepted that mice maintained under these conditions are cold stressed. When mice are inactive and sleeping in the daytime, their zone of thermoneutrality associated with a basal metabolic rate is 30-32 ⁰C. If given a choice, mice will use thermoregulatory behavior to seek out thermoneutral temperatures during the daytime. The cold stress of a vivarium can be problematic to researchers requiring an animal model that not be stressed metabolically. However, it may not be practical or economically feasible to maintain an animal vivarium at thermoneutral temperatures. One problem with raising the Ta of a vivarium is that personnel wearing protective equipment will be subject to considerable heat stress. In this paper, we present plans for the construction and operation of a device that allows mice to occupy a hut maintained at an approximate thermoneutral temperatures (30-32 ⁰C). The device is made of inexpensive, readily available materials and utilizes a disposable hand warmer (HotHands®) as a heat source. One hand warmer provides a thermoneutral environment for approximately 12 hours. This device is easily adapted to a standard mouse or rat cage and requires brief maintenance each day to change the heat pad. With this device in a standard cage, mice can select an environment associated with thermoneutral conditions during the daytime when inactive and sleeping. At night, the mice are more active, have a higher metabolic rate, and prefer cooler Ta’s. Egress from the warmed plate allows mice to seek cooler Ta’s at night.
