Each year, over 120 million laboratory rats and mice are used. Many are used to studying distressing conditions like cancer, arthritis and chronic pain, and almost all spend their lives in small, empty box-like cages.
Rats and mice are chronically stressed because of the restrictive housing, changing their biology. Concerns about their welfare and how well they represent typical human patients are raised by this.
The impact of housing on health outcomes was identified by taking data from over 200 studies that investigated the effects of cage design on health outcomes.
The small, barren cages typical of labs were compared with better-resourced housing.
The animals in conventional cages became sicker than those in better-resourced housing. They developed larger tumors if they were given cancer.
Conventionally housed animals had an average lifespan reduced by 9 percent. Scientists have known for decades that rats and mice want more comfort, exercise and stimulation than is normally provided, and that conventional cages induce abnormal behavior and anxiety.
This is the first evidence that they cause chronic distress severe enough to compromise the health of animals.
Mouse are healthier when they are contained in stimulating environments. Aileen MacLellan wrote the book.
Evidence of methodological problems and poor reporting of experimental details were found in our study. The rodents used were male-biased, with few studies using female animals.
Two-thirds of the studies did not fully describe the living conditions of animals. Many previous suggestions that rats and mice living in barren cages that lack stimulation may not be suitable models are supported by our findings. Male research animals are often overweight and chronically cold.
We think that the reliance on &CRAMPED& animals could help explain the current. There are already examples of research studies generating different conclusions depending on how their animals are held, and we want to assess the extent to which this occurs.
At least 50 percent of research results can't be replicated when other scientists re-run a study, and that housing is critical for rodent biology, yet often poorly described in papers.
The well-being of laboratory mice is dependent on housing. Understanding animal research is available in the Wikimedia Commons.
Only a small percentage of the world's research animals live in Canada. 1.5 million to two million animals are being unintentionally stressed, something that anyone who cares about animals will find concerning.
If animal housing changes research conclusions, that has financial implications as well. Canada spends billions of dollars on health research.
If half of that is animal-based, of which only 50 percent is reproducible, then Canada may be spending around CA $1 billion a year on non-replicable animal studies.
Under 5 percent of studies yield usable medical benefits for humans. The Canadian public expects 60 percent of animal work to lead to new human drugs.
Canadian standards require that mice be provided with materials that will keep them warm, but is it time to improve them further?
The shoeboxes that rats and mice currently live in should stop being ignored as if a neutral backdrop, and instead be seen as a determinant of health, one we can modify, improve and study. It would allow us to better model the diverse social determinants of human health and improve animal well-being at the same time.
Georgia Mason is a professor at the University of Guelph and Jessica Cait is a student.
This article is free to use under a Creative Commons license. The original article is worth a read.
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