Daily Archives: April 25, 2017

How animal enclosures are designed to meet the needs of laboratory animals

Having worked in animal research for over 14 years now I have not only gained a comprehensive knowledge of the requirements for animals used in research but have also seen significant improvements in this field. Currently, I work at as a Site Manager where I oversee three animal units.

The role of an animal technologist varies dependent on experience but all are there to provide the best possible life to animals in research. Trainee animal technologists will often perform general husbandry duties such as cleaning cages, feeding, and watering, whereas senior technologists may be involved in colony management, scientific procedures etc.

During my career, and the many tours of research labs I’ve given, one of the common discussion is the type of cages used and how they vary so much between species.

are stipulated by Home Office and as well as any additional institutional requirements beyond this law. Providing the correct type of environment is essential for species to exhibit their natural behaviour.

Example of UK minimum cage sizing for M. mulatta

Housing requirements vary between species but here are some examples of why cages are designed in such a way:

Primates-free fake id

Primate caging is typically tall as this enables the animals to feel more secure, as in the wild they would use the trees to climb high and get away from prey. Providing higher cages also allows for a more complex environment. Bars are often horizontal to allow the animal to climb the cage and maximise this as much as possible. Cages are normally made out of steel to ensure the animals are safely contained and also withstand potential damage in what are often a strong and intelligent species.

Cages are often multi-tiered to allow primates better utilisation of cage height and enable primates to get away from each other when necessary.  Environmental enrichment such as mirrors and perches provide further security to primates.

Primates are socially housed in multi-tier caging. The perches allow the primates to watch what is going on around the room.

Rodents

Rodents have much smaller cages which are normally made up of a plastic, such as polysulfone. These plastics can withstand high temperatures during cleaning and have been shown to last a long time. Traditionally, animals were kept in open top caging but in recent years there has been a movement towards individually ventilated cages (IVCs). IVCs provide a more stable environment by having sealed caging and using air handling units for filtration; this has, in turn, provided a better environment for animal welfare and research. Controlling for the environment can both help control experimental variables, and prevent risks to animal health from external pathogens.

While the caging appears to be relatively small for rodents it is designed around the need of the animals. Rodents are often social species and in some cases larger spaces can cause anxiety due predator/prey relationships.

Environmental enrichment is used to encourage natural nesting behaviours which can be seen in the wild. In recent years red boxes have been implemented in some cages, humans can see through these but animals don’t see through this colour in the same way, therefore this allows better monitoring while making animals feel safe and secure.

Individually Ventilated Cages

Rabbits

Rabbits are often housed in floor pens as this provides space to exercise and express their social behaviour. Rabbits which are kept grouped housed tend to show less stereotypic behaviour and greater activity. Previously, rabbits were predominantly housed in single cages which caused more stress to the animals.  Enclosures are normally made up of wood frame with metal bars or completely metal frame with very small holes to prevent animals escaping.

Environmental enrichment such as cardboard boxes, hay/straw and raised areas can also provide more security and natural behaviours therefore reducing any abnormal behaviour which may be seen otherwise.  As albino rabbits are often used in research, boxes also provide a darker place to prevent damage to the retina of the eye.

Final thoughts

As humans we often believe that larger housing is better, just look at people who often want a huge home, but this doesn’t mean that an animal will be comfortable with this. The key is to tailor this to each species/individual’s needs for the highest welfare standards. Animals which naturally live in holes, or nests, often feel comfortable with less space compared with other animals. Other additions to accommodation such as environmental enrichment can enable expression of natural behaviour further and have significantly increased in recent years, no more barren cages!

In my 14+ years working with research animals, I have seen a huge amount of change. Improvements in caging and enrichment benefit not only the animals, but the pursuit of good science as well, and we should welcome it. I am also a strong believer that this has also improved the morale of staff, after all we all want the best for animal welfare which in turn will lead to good science.

Stephen Woodley