Between 3Rs: Refining the Housing Experience for Lab Mice
Research Models
Elizabeth Doughman

Between 3Rs: Refining the Housing Experience for Lab Mice

How can you encourage male mice to play nice in the sandbox? Try the Mouse Cubby, an innovation in refinement to current environmental enrichment devices.

Social housing is an easy way to improve laboratory animal welfare. Unfortunately, male mice can be quite aggressive, making it difficult to house multiple rodents in the same cage.

The Mouse Cubby, developed by Bret Tallent at University of Arizona  and winner of the 2017 TurnKey Innovation in the 3Rs Award, allows multiple male mice to be housed together without fuss.

What is the Mouse Cubby?

BT: The Mouse Cubby is a disposable cage insert that effectively divides half the cage into thirds, producing three burrow-like compartments and a “great” room that all animals have access to. It is made from food grade corrugated cardboard and comes irradiated, or can be steam autoclaved.

The Mouse Cubby has been shown to reduce aggression in group housed male mice by 50 to 90 percent. It reduces fighting, satisfies gnawing behavior, and provides an unobstructed view of the animals in the cage. Further research has shown that the Mouse Cubby does not alter cognitive testing responses to standard neurological behavior tasks, although it has shown statistically significant improved outcomes to anxiety-like behavior in the elevated plus task.

How is the Mouse Cubby a 3Rs innovation?

The Mouse Cubby creates multiple divisions within the cage that can be accessed at any time by any animal in the cage, and allows for proper social cues for subordinates such as removing themselves from line of sight, or escape. This de-escalates social encounters that would otherwise result in increased aggressive behavior of the dominant animal(s).

The Mouse Cubby also divides the cage from floor to ceiling, appealing to the thigmotactic nature of mice and provides them the opportunity to manipulate their environment by gnawing holes through the walls. As there are three “burrows” and a large shared space, there is no need for fighting over a limited resource or territory. Because the Mouse Cubby is so effective at reducing aggression, it also reduces the need to separate, or even euthanize animals.

A further innovation of the Mouse Cubby is that it allows complete viewing of the animals by animal care personnel from the front to the rear of the cage. There is no need to pull the cage out of the rack or open it up to check on the animals inside. It is for these reasons that the Mouse Cubby is an innovation in refinement to current environmental enrichment devices and animal welfare programs.

What sort of 3R innovations do you hope to see in the next 50 years?

I would love to see advancements in artificial intelligence. Current computer models or in-vitro testing can only do so much. The living system is so complex that interactions between different systems is impossible to measure given current technology. Advanced, intelligent computer models that can mimic a living system is the only true way to reduce, or even replace animals in research.

How do you think the 3Rs has changed animal research in the last 50 years?

The impetus of 3Rs thinking has produced great strides in animal welfare and scientific rigor. Housing and husbandry have improved, as has veterinary care. Refinements in care and experimental procedures have developed standards that have led to scientifically reproducible data and in turn, reductions in animal use.

Concern over environmental enrichment and natural behavior producing a reliably healthy, well-adjusted animal have become common place. No longer is the animal just a “living test tube.” It is viewed as a valuable member of the research team; whose use many investigators see as a privilege. So perhaps the biggest change in animal research is the mindset of researchers and technicians regarding the value of the animals they have been using.

Are the 3Rs still an important guideline for animal research today? Why?

Yes, without a doubt. It is far easier to revert to “well, this is how we’ve always done it and it works fine,” than continue evolving our approaches to animal research to minimize the impact on animals. Every stride we make produces better quality research, better quality animals, improved scientific rigor, and reproducible results.

All great strides require vigilance, and progress is never made by reverting to the past. The 3Rs will never be fully implemented until we can perform full living system research without the living system of the animal.

Between 3Rs is a Q&A series created by the Charles River Laboratories’ Eureka blog and ALN Magazine to highlight the importance of the 3Rs—replacement, reduction, and refinement—as guidelines for ethical animal use in biomedical research. If you are interested in being a part of the series, contact [email protected] or [email protected].