Joseph Garner, PhD, a mouse admirer and advocate, has found that giving mice the simple means to build a cozy little nest helps the animals warm themselves and produce more, healthier pups. For the small cost of nesting material – 62 cents a cage – mice will reproduce babies worth several thousand times that amount within six months, he and colleagues found in a recent study.
“I think that’s a pretty good return on investment,” Garner told me. Garner is an associate professor of comparative medicine at Stanford who’s been studying animal welfare for more than two decades.
He notes that laboratory mice are kept in cold conditions because it suppresses their aggressive tendencies. But as the mice labor to warm themselves, it changes their physiology – and the outcome of valuable experiments. That may be one reason, Garner theorizes, that so many drugs tested in mice end up not working in people.
In a previous study, he and fellow researchers found that if mice are supplied with shredded paper, they’ll build a comfortable little nest that allows them to naturally regulate their temperatures. Nest-building also helps the animals decrease their stress and anxiety levels, he says. Now, he and colleagues find that nest-building is also very cost-effective and could save laboratories many thousands of dollars. In their latest study, nude mice (so-called because they have no fur) that were provided with nesting material produced significantly more pups, and more of the pups survived in the warmer environment.
These animals, which are often used in studies involving genetic modifications, are costly to purchase – between $47 and $128 each. So better breeding means significant savings for research labs.
“Even small improvements in breeding and pup survival are obviously a huge benefit to the mouse’s well being, but they can have an enormous economic impact,” Garner told me. “Maybe by helping the animals and giving them resources they care about, we can also alleviate some of these entrenched problems. Essentially good well being makes for better business and better science.”
Environmental enrichment for animals is a trend that is sweeping the industry, Garner says, and he hopes the work will help move it even farther along.
His latest study, a collaboration with Brianna Gaskill and other researchers at the Charles River laboratory, appears online in the journal Applied Animal Behaviour Science.
Photo by Thomas Huston