Shedding Ultraviolet Light On Welfare In Laboratory Rodents: Suggestions For Further Research And Refinement
Campaigning to end the use of animals in laboratories is made more difficult by the fact that most of the animals used in labs – namely rodents, such as rats and mice – are not afforded any legal protection or even counted in animal testing statistics. This study demonstrates the kind of improved minimal welfare measures that have been suggested in the European Union. In an effort to give laboratory rodents a better life, researchers suggest adding UV lights to rat and mouse enclosures, as rats use their UV vision to interact with their environment and other animals.
Rats and mice have complex biologies and interact with the world in a way that differs greatly from humans. In a laboratory setting, many of these natural biological behaviors, such as using their sensitivity to UV light, cannot be expressed. This study looked at potential ways that rats and mice can have their lives improved by the addition of UV light to their enclosures. These animals use their UV vision to see urine markings, which influences everything from their territory, communication, aggression and more. In some rats, it has been shown that their UV vision helps in pattern recognition. According to the authors of this study, “the fact that mice and rats have a different range of visual perception to humans has been ignored” by science as an important aspect of rodent life.
In labs, animals are generally housed “in artificial light (such as standard tube lights and standard lightbulbs) which contain very little UV light. Moreover, the animals are most likely deprived of natural light.” For rats and mice, who have a broader range of vision than humans, this negatively affects their welfare. Even though “some may argue that being able to use the full range of the visual spectrum is not important for mice and rats, since it has been demonstrated repeatedly that olfaction and scent marking is necessary for communication in mice and capable of guiding behaviour and modulating social tolerance,” the authors of this study explain that all of the previous research was “carried out under artificial light conditions and no studies have […] assessed differences in social behaviour in artificial versus natural light settings.” Previous findings have been based on studies where UV light was not a variable.
This paper is aimed at providing rats with improved living conditions when they are used in laboratories so that they produce “better” data for researchers; it wasn’t carried out for rodents to improve their lives generally. “We need to consider whether denying laboratory rodents the ability to use their UV vision may influence their behaviour (both in the home cages and in behavioural tests in, eg neuroscience) and the welfare,” they say, before adding that “being unable to utilise visual cues from urine markings may affect the social behaviour and competences of group-housed animals.” As a “best solution,” the authors suggest providing artificial light with a more natural composition, which may improve rats ability to see and interact with their surroundings, but unfortunately it doesn’t change their fate in the lab.
The welfare of laboratory rats and mice is sought to be optimised through adjustment of a variety of environmental factors, including light intensity and photoperiodicity. However, the fact that rodents are able to perceive ultraviolet (UV) light tends to be ignored. The importance of being able — as a rodent — to utilise this part of the visual spectrum has not been studied in great detail, but suggestions, based on the evolutionary success of this trait, indicate that the deprivation of ultraviolet light in mice and rats could perhaps impact negatively on the welfare of these animals. Further research into the importance of having a UV light source available to rats and mice should be encouraged.