A new relationship with animals, nature and each other.

Researchers Revolt at Larger Rat Cages


Bob Adams is upset. He may have to spend an extra one-time $1.50 on each of the animals at the rat and mouse complex he supervises at Johns Hopkins University.

The National Institutes of Health is recommending (just recommending, mind you, not insisting) that the size of their cages be increased a little. The average rat family, for example, would get 210 square inches of floor space rather than the current 140. Mice would get a little more space, too.

On any given day at the main housing facility for rodents at John Hopkins University, there are about 200,000 rats and mice in residence. They live in about 40 rooms, each with 1,000 plastic cages the size of shoe boxes. A family of rats or mice – mom, dad and each litter of babies – live their whole lives in this “home”. It would cost Dr. Hopkins $300,000 to replace all the cages. The turnover rate for rats and mice is very high – sometimes just days or weeks – so the cost per mouse over the long term is vanishingly small.

But Dr. Adams is upset and angry. “There is more work, there is more cost for everybody, for our whole operation,” he moaned on National Public Radio.

Our heart goes out to him and to his budget of billions.

No one knows exactly how many rats and mice are used and killed in experiments every year at John Hopkins or any of the other laboratories. That’s because, according to government standards, mice and rats (and birds, too) are not considered to be animals, and therefore are not covered under the reporting requirements of the Animal Welfare Act.

But laboratory scientists are upset all across the country. Joseph Thulin, director of the “biomedical resource center” (no, you’re not so much a living creature, just a biomedical resource) at the Medical College of Wisconsin told NPR that these recommendations have not been fully researched.

“I would not want anyone to think that the research community doesn’t want to implement new guidelines because they don’t care about their animals. That is not the case at all,” says Thulin. He says it’s just that there’s been very little research on rodent housing, and there’s no evidence to support the idea that increasing the cage space in the way that’s been recommended “will have any measurable positive impact on the animals.”

Yes, indeed. Let’s do a five-year study. We can put hundreds of mice in different size plastic boxes and implant wires into their brains to see which size of box makes various regions of their brains light more on a computer screen.

Come to think of it, Drs. Adams and Thulin should be able to get enough funding for this important research to more than cover the $1.50 per animal at each of their facilities. They might even come out ahead.

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The NPR story is here. The government guide is here. And below are charts from that guide showing recommendations for cage sizes for different animals (or, in the case of mice, rats and bird, non-animals):