Researchers know that laboratory mice prefer to be housed in warmer temperatures than those in which they are typically kept in the lab. While temperatures of about 30 degrees Celsius (86 degrees Fahrenheit) are ideal for the rodents, the animals are routinely housed at temperatures between 20-26 degrees Celsius (68-79 degrees Fahrenheit). This isn’t a new discovery: In fact, we reported on this issue four years ago in a previous Science First, based on findings which suggested that this variable may be contributing to the failure of animal data to translate to people.
So why are laboratory mice housed at lower temperatures? There are many reasons, not the least of which is the fact that researchers working with the animals are simply more comfortable at cooler temperatures. The lower temperatures also reduce the odor generated from the animals. In addition, some studies have reported that mice are “unmanageably aggressive” when kept warm. Guidelines regarding housing mice therefore recommend the 20-26 degree Celsius range, and mention that nesting material should be available to help keep the animals warm.
The downside of housing mice in cooler conditions, however, is that the mice suffer from what is known as “cold stress.” As a result of trying to generate heat for warmth, they may eat more than normal. Their metabolism changes, and their heart rate changes. Ultimately, this has implications for their use as models in the lab and the quality of data that is produced.
According to immunologist Bonnie Hylander, “Most people only look at results from experiments at standard lab temperatures. They’re not necessarily aware that if you repeat the experiments with mice at a different temperature, you might get a different outcome.”
While researchers concluded that more work needs to be done to optimize mouse studies so that they translate better to humans, we have a different opinion. A cold mouse is still a mouse, and studies like this highlight the fact that the research community needs to work with more human-relevant, non-animal methodologies. Continuing to invest in flawed animal studies only wastes time, resources and animal lives.
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Are lab mice too cold? Why it matters for science
April 19, 2016
A typical mouse laboratory is kept between 20 and 26 degrees C, but if the mice had it their way, it would be a warm 30 degrees C. While the mice are still considered healthy at cooler temperatures, they expend more energy to maintain their core temperature, and evidence is mounting that even mild chronic cold stress is skewing results in studies of cancer, inflammation, and more.
For more information, see: EurekAlert