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Animals

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Test animals are treated as humanely as possible.....

One of the hallmarks of the scientific method is that experiments must be standardized and repeatable. But what if, in the push to "standardize" and remove all other potentially compounding factors, we've created conditions so unnatural that our experiments themselves become invalid?

It's a question that's long overdue. After all, it was once thought that we could study an animal like a chimpanzee in a zoo or cage to learn all about it. But when Jane Goodall studied them in the wild, she found they were very different. Now researchers at the 35th Congress of the International Society for Applied Ethology (the study of animal behavior) are questioning the validity of "controlled conditions."

Scientists routinely use laboratory animals, particularly mice, to test new medicines, medical procedures, drugs, foods, and more. To reduce the number of variables between animals and — it is hoped — to obtain more accurate study results, the animals are genetically homogenous and raised in standard, clinical cages, with little stimuli other than the experiment itself. This clean, sterile environment is considered healthy and normal.

But in 1996, a Swiss animal behaviorist noticed that mice and rats reared this way might actually be decidedly abnormal. Using infrared cameras to spy on the nocturnal lab mice in the dark, researchers found that most of them behaved very strangely after their handlers had gone home for the day. The mice continuously repeated seemingly meaningless behaviors, such as cage biting and cage scratching. Such repetitive actions by animals are called stereotypies, and they are often considered signs of boredom or stress. Still, the mice were thought to be basically "normal" and their actions attributed to mere habit.

In humans, however, the presence of stereotypies is thought to indicate damage to part of the brain called the basal ganglia, which is believed to regulate how we initiate movement. Now new evidence suggests that stereotypies may actually indicate permanent brain damage in other animals as well. Last month the journal Nature reported a University of California study that examined parrot behaviour using a procedure that is normally used to test for damage to human brains — particularly to the basal ganglia. Parrots that exhibited stereotypies failed the test, indicating potential damage to this region.

The researchers are now testing rodents, and it is likely that the results will be similar. Rodents spend a great deal of their lives searching for food and building nests. Denied an outlet for such basic instincts, the animals suffer stress and possibly impaired brain function. Indeed, studies have found that rodents kept in enriched environments perform better in memory tests.

If test subjects are already impaired, scientists may be inadvertently invalidating studies by relying on data from brain-damaged animals. As behavioral scientist Joseph Garner points out, "If the abnormal behaviors that are so common in captive animals are indicative of abnormal brain function, then these animals can hardly be considered to be good models of normal animal or human functioning."

This also raises questions about the validity of studying the behavior of large mammals such as killer whales in captivity, where they are confined to small pools and receive little natural stimuli. In the wild, killer whales can travel great distances every day, moving and hunting in family groups. It should be obvious that the behavior of such animals in captivity will not reflect anything like the true behavior of their wild counterparts.

Clearly this issue needs to be examined further. Ethically, we must ensure that test animals are treated as humanely as possible. Practically, if the animals that we use for experiments are already impaired, then are the conclusions we draw valid?

"There may be simple ways to solve the problem. A recent study done at Utrecht University in the Netherlands examined ways to create a more natural environment for test rodents, such as adding nesting material and scattering feed so rodents can "forage." It found that such steps can be taken without jeopardizing experiments and concluded, "Thus, there seems to be no good reason to deprive laboratory mice of this form of enrichment."