When selecting animal models for conducting scientific research, welfare should be the main priority. This article considers the effects of different housing strategies for mice and how PhenoTyper offers researchers insight into animal well-being.

There is clearly a considerable ethical argument for optimizing the well-being of animals used in research. William Russel and Rex Burch infamously made this case in their 1952 paper The Principles of Humane Experimental Technique, in which they offered a blueprint for the considerations of animal welfare in science.1

The value of eliminating any unnecessary suffering and distress in animals should be readily apparent to most. But the argument for animal welfare extends much further than this.

A significant volume of research demonstrates that animals whose well-being is endangered are more likely to present physiological and behavioral abnormalities.2,3 Therefore, carefully controlling all factors that contribute to an animals well-being insofar as those that can be evaluated should be the guiding principle to guarantee experimental validity.

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Since the most frequently used animal models are mice in biomedical research, maximizing their well-being is crucial. The housing that mice are kept in plays a key role in this.

Naturally, mice are animals, so it is generally advised that when possible (and partible) they should be housed in groups.4

However, inter-male aggression is a major welfare concern for mice housed in captivity when it is not possible for them to escape each other as male mice do not naturally share territories.5 This means that paired housing or single housing is often a more feasible choice.

Other contributing factors experimental design and disease control in particular also make single housing a preferred choice in many cases. There are those that advocate for the use of cage dividers that allow sensory but not physical contact between neighboring mice to enable some level of social interaction.6

The immediate effects of housing on mices well-being, behavior and physiology are still up for debate. However, research shows that the single housing of mice is associated with various physiological ailments.

These include a reduction in growth rates and reduced lean body mass during growth, increased predisposition to obesity in adulthood and raised levels of visceral adipose tissue mass.7,8

Behavior can be influenced by housing too. Single-housed mice are known to exhibit anxiety- and depressive-like behaviors as well as broken cognitive function when compared to pair- or group-housed mice although these effects are also dependent on a range of other environmental and physiological factors.911

Separated pair housing using cage dividers seems to have some contrast in behavioral and locomotor performance when compared to single housing although it is not completely clear whether this corresponds with a difference in well-being.

Ideally, all of these changes should be considered in the research goals of experimenters using mice models.

In the long term, housing conditions tend to be at the mercy of experimental parameters. For instance, to prevent mice from damaging each others cannulas, single housing is mandatory for studies involving the cannulation of mice.12

Studies of energy balance regulation also tend to drift towards single housing so that the food intake and thermal profiles of each mouse can be carefully monitored. Single housing in individually vented cage (IVC) systems can also help prevent disease transmission between the mice.

Still, considering whether experimental parameters could permit paired (or separated pair) housing is useful if wanting to reduce stress, accomplish longer testing periods, and enhance experimental validity.

A number of experiments involve testing mice in a special environment away from their housing however, testing them in their home environment offers another chance to reduce stress levels and eradicate the confounding effects of a change in environment.13

Housing can have significant behavioral and physiological effects on mice: phenotypically, socially housed mice are not the same animal as mice that have been individually housed.

Observing animals in their home cage and comparing their behavior throughout the experiments is vital to understanding the effects of various housing paradigms.

So, whether opting for social or separate housing, it is essential to make sure everything is carefully considered and that a scoring system is in place.

PhenoTyper is a fully integrated and automated cage monitoring system. By facilitating simple monitoring of individual animals in their home cage, PhenoTyper offers researchers access to increased resolution when assessing animal model behavior within a particular housing paradigm.

Image Credit: Noldus

PhenoTyper can be customized to suit individual research needs. Each configuration is comprised of a bottom plate, four interchangeable walls, and a PhenoTyper top unit. A variety of walls are available to accommodate any configuration, with attachments for accessories such as feeding stations, drinking bottles and shelters.

The PhenoTyper top unit houses LEDs and a camera for automated tracking, with other sensor and stimuli options available. These can also be used to transmit feedback on animal behavior to EthoVision XT.

Automated tracking using EthoVision XT can provide full data integration and allow automation of experiments. EthoVision XT also offers precision tracking and good calculation of an extensive range of physiological and behavioral parameters while offering researchers access to unrivaled versatility in data processing and visualization.

As a result, EthoVision XT is considered to be the most cited video tracking system in the world.14

Image Credit: Noldus

To discover how PhenoTyper can offer deeper insight and faster results, contact Noldus today.

Noldus Information Technology was established in 1989 by Lucas Noldus, founder and CEO of the company. With a Ph.D. in animal behavior from Wageningen University, he developed the companys first software tool during his research in entomology. Noldus has strived to advance behavioral research ever since, evolving into a company that provides integrated systems including software, hardware, and services.

We now offer a wide range of solutions for research in animal and human domains, including biology, psychology, marketing, human factors, and healthcare. We work with leading suppliers and develop innovative, state-of-the art products. We also offer excellent technical support and customer care. As a result, our systems have found their way into more than 10,200 universities, research institutes, and companies in almost 100 countries.

The success of our company is determined to a large extent by the enthusiasm and creativity of our employees. We encourage each other to think outside the box, which leads to unique products and services for our customers. And we are always on the lookout for new talent!

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The Effects of Different Housing Strategies for Mice and Insights Into Animal Well-Being via PhenoTyper - News-Medical.Net