A Device that Allows Rodents to Behaviorally Thermoregulate when Housed in Vivariums

Laboratories and vivariums typically are maintained at ambient temperatures of 20 to 24 °C, leading to cold stress in mice. When mice are inactive and sleeping during the light phase, their zone of thermoneutrality associated with a basal metabolic rate is 30 to 32 °C. If given a choice, mice will use thermoregulatory behavior to seek out thermoneutral temperatures during the light phase. The cold stress of a vivarium can be problematic to researchers requiring an animal model that is not stressed metabolically. However, it may not be practical or economically feasible to maintain an animal vivarium at thermoneutral temperatures. One problem with raising the ambient temperature of a vivarium is that personnel wearing protective equipment will be subject to considerable heat stress. Here we present plans for the construction and operation of a device that allows mice to access a heated floor that is maintained at an approximate thermoneutral temperatures (30 to 32 °C). The device is made of inexpensive, readily available materials and uses a disposable hand warmer as a heat source. One hand warmer provides a thermoneutral environment for approximately 12 h. This device is easily adapted to a standard mouse or rat cage and requires only brief daily maintenance to change the heating pad. With this device in a standard cage, mice can select a warmer environment associated with thermoneutral conditions during the light phase and cooler ambient temperatures during the dark phase.