Labs Size Up New Guidelines For Rodent Cages Mice and rats are the most common lab animals. That's why some influential new guidelines on how to house mother rodents and their babies have created an uproar. Some experts at research centers say there's no evidence that making costly changes will really benefit the animals.

Labs Size Up New Guidelines For Rodent Cages

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This next report brings to mind the old book, "Mrs. Frisby and the Rats of NIMH," bunch of lab rats featured prominently in a classic children's story. It turns out they're pretty smart, civilized. In real life, of course, scientists use millions of rats and mice each year as they seek to understand and treat everything from cancer to diabetes, and the government has rules to care for them.


To get government funding for their work, researchers have to follow animal welfare guidelines. Those guidelines have just been updated for the first time in 15 years, and new recommendations for female rodents and their babies have caused an uproar. Here's NPR's Nell Greenfieldboyce.

NELL GREENFIELDBOYCE, BYLINE: Mice and rats are the most common lab animals. They can be genetically altered, they reproduce quickly, they're ideal. But managing all these rodents is no small matter. I recently visited the biggest recipient of research funds from the National Institutes of Health. That's Johns Hopkins University in Baltimore. Its main facility for housing rodents is nearly the size of a football field.

BOB ADAMS: This is a fairly typical animal room in this facility. It holds between 900 and 1,000 cages.

GREENFIELDBOYCE: Bob Adams is the veterinarian in charge here. His staff looks after some 40 rooms just like this, full of cages the size of shoeboxes.

ADAMS: With, say, anywhere from one to five mice per cage, so close to 200 and some-odd thousand mice.

GREENFIELDBOYCE: The cages are made of clear plastic. They sit into tall racks that line the walls. Each cage has its own ventilation and water supply. All of this has been set up to meet recommendations laid out in something called The Guide for the Care and Use of Laboratory Animals. Everyone funded by the National Institutes of Health must comply.

Recently, the guide was revised for the first time since 1996, and the research world is now in a tizzy over page 57. It lays out new recommendations for the minimum number of square inches that should be used to house a female mouse or rat and her babies. To explain his concerns, Adams pulls out a cage.

ADAMS: So here's a litter. Well, there's multiple females in here.

GREENFIELDBOYCE: Hairless pink babies squirm in one corner. There's a tangle of adults with dark fur over by the water valve. Adams says there's probably a male in here with a harem. One male plus two or more females can produce lots of mice quickly.

But as Adams interprets the new guidelines, this would no longer be possible in this shoe box-sized cage. The guide seems to say it's only big enough for one mother and her babies, plus one other adult.

Adams is worried that Johns Hopkins may have to make major changes to keep its government funding.

ADAMS: The effect would be, we would have to buy more of this caging, and our estimate was somewhere around $300,000 worth of caging, at least, and then find a place to put it.

GREENFIELDBOYCE: Then he'd have to hire more staff to manage those cages and wash them.

ADAMS: Bottom line is there's more work, there's more cost for everybody, for our whole operation.

GREENFIELDBOYCE: Across the country, other research institutions looked at the new guide and came to the same conclusion. The National Association for Biomedical Research estimated that nationwide, implementing the new space guidelines for breeding rodents would likely cost hundreds of millions of dollars - money that then couldn't be used on research. Government regulators have been deluged with letters of protest.

One of them came from the Medical College of Wisconsin, which has one of the largest colonies of academic research rats in the world. Joseph Thulin directs the college's animal resource center. He says animal welfare is important.

JOSEPH THULIN: 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.

GREENFIELDBOYCE: But there's been very little research on rodent housing. Thulin says it's just not clear that the new guidelines will result in any benefits.

THULIN: There is no evidence to support that increasing the amount of cage space by the amount that's recommended now, that that would have any measurable positive impact on the animals.

GREENFIELDBOYCE: Meanwhile, the people who actually wrote the new recommendations say all this concern is the result of a big misunderstanding.

JANET GARBER: Certainly I personally was very surprised at the reaction or at the way some people were interpreting what was written.

GREENFIELDBOYCE: Janet Garber chaired the committee of independent experts convened by the National Research Council to revise the animal care guidebook. The old version had no specific guidance on how to prevent overcrowding when breeding rodents. The panel simply thought it would be helpful to set some benchmarks.

GARBER: There are very, very few requirements in the guide. There are very few musts in the guide. And certainly, within the context of these housing recommendations, they are in fact recommendations. Yes, they're minimum recommendations, but they're a starting point.

GREENFIELDBOYCE: That's the position taken by the National Institutes of Health. The director of its lab animal welfare office told me in an email that she also was surprised by the controversy. She said the experience of her office was that labs currently house their rodents appropriately.

A statement on the agency's website indicates it still will be possible to put more breeding rodents in a cage than the guide recommends, and researchers say, that is somewhat reassuring.

But it won't be business as usual. Because the government's statement goes on to say that if scientists want to do that, they'll have to justify it, and show that things like the animals' health or behavior won't suffer.

Plus, the government warns that, quote, "blanket, program-wide departures from the Guide for reasons of convenience, cost, or other non-animal welfare considerations are not acceptable." It's left Bob Adams at Johns Hopkins scratching his head.

ADAMS: I guess the importance of what we're talking about is the uncertainty of what this is going to do to us.

GREENFIELDBOYCE: He says all this is not trivial. Researchers have to meet the government's standards to safeguard their funding. So, how to move forward, shell out the money for more cages when science budgets are already tight, or try justifying their current practices to see if they're accepted?

ADAMS: We're going to have to thrash this out and see - how do we interpret this now?

GREENFIELDBOYCE: All of this ambiguity has also displeased some animal welfare activists - for a different reason. They feel that researchers shouldn't have been given an out. Kathleen Conlee is with the Humane Society of the United States. She says overcrowding can be a real problem, and that officials should carefully scrutinize any efforts to breed rodents in less space.

KATHELEEN CONLEE: If we are going to be using millions, or tens of millions of rodents in this country, we do have an obligation to the welfare of these animals and hope that the National Institutes of Health will strictly enforce their recommendations in the guide.

GREENFIELDBOYCE: The National Institutes of Health is taking comments on the rodent housing issue until the end of the month. And research institutions have about a year to evaluate their programs and decide whether they need to make changes to comply with the new guide.

Nell Greenfieldboyce, NPR News.


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