Washington

Changes to animal welfare rules proposed by the US Department of Agriculture (USDA) have been met with concern from a group of US researchers. The scientists last week urged the agency to replace its current working definition of distress in laboratory animals, which they describe as “subjective” and “unenforceable”.

The researchers had taken part in a workshop held by the Federation of American Societies for Experimental Biology (FASEB) to set a policy agenda on animal welfare. The meeting followed a call from USDA in July for comments on proposed rules for classifying animal pain and distress in the laboratory.

Painful question: what is distress for a lab mouse? Credit: P. GONTIER/EURELIOS/SPL

USDA is seeking suggestions for an official definition of ‘distress’. It has also outlined alternative ways to measure pain and distress in animals. One idea is a three-tier classification of procedures — none/mild, moderate, severe — based on the level of pain experienced by the animal over the whole trial.

This categorization is similar to systems used in countries such as Canada and Switzerland. But many researchers would prefer a method, based on the current rules, that focuses on whether or not analgesic or anaesthetic drugs are used to alleviate pain during a particular period of the trial.

Controversy over pain has been smouldering for years, says Ron DeHaven, deputy administrator for animal care with USDA's Animal and Plant Health Inspection Service.

Both researchers and animal rights advocates point to areas of confusion or ambiguity in the present rules, stemming from a failure to define terms or clarify the categories to be reported. The word ‘distress’ appears as often as ‘pain’ in the Animal Welfare Act of 1966, but its exact meaning is never specified.

DeHaven says that this was more by oversight than intent. Unofficially, the department defines distress as “a state in which an animal cannot escape from or adapt to the internal or external stressors or conditions it experiences, resulting in negative effects on its well-being”.

Many participants in the FASEB workshop prefer another definition already adopted by the Institute for Laboratory Animal Research in Washington DC. This describes distress as “an aversive state in which the animal is unable to adapt completely to stressors and the resulting stress and shows maladaptive behaviour”. Maladaptive behaviour usually means self-mutilation, such as an animal chewing off the tip of its tail.

Animal advocate organizations say the definition is too conservative. “By the time an animal starts to exhibit maladaptive behaviours, it may have been under stress for some time,” says Rick Bogle of In Defense of Animals.

But Kathryn Bayne, associate director of the Association for the Assessment and Accreditation of Laboratory Animal Care, says that the phrase “negative effects on its well-being” is too general to be enforceable.

http://www.aphis.usda.gov/ppd