Bedding For Laboratory Animals

Andrew Aston

The type of bedding used in a facility can greatly influence the results of experimental procedures.
Bedding is one of the most important items within the microenvironment of laboratory animals. It provides warmth, maintains the environment of the cage, and adds to the overall welfare of the animals in care. It is an essential item for all animals in captivity.
Two things to think about when considering bedding choices are the needs and requirements of the animals to be housed and what experimental procedures will be performed. There are many different types of bedding available on the market and it can be a bewildering experience to choose the best type that meets all of the requirements.
It’s not only small animals that require bedding as a cage substrate—larger species should be provided with suitable pen/enclosure bedding to prevent pressure sores when resting and also to give warmth and comfort. Hay and straw are commonly used for large species, and clean woodchip is good bedding for pigs, sheep, and goats.
Poor choice of bedding can result in welfare problems for the animals, especially sick or injured animals. Care needs to be exercised to ensure that the bedding provides a source of warmth and insulation, and enables the animal to keep dry within the caged environment. These are essential qualities expected of any bedding material.
TYPES OF BEDDING
Corn cob is manufactured using processed corn cobs, a natural ingredient with no additives that is environmentally friendly and completely biodegradable. They provide animals with a dry surface and most are produced in modern plants under strict clean conditions. They are available in different cob sizes depending on individual requirements.
Paper bedding is usually provided to sick or recovering animals and is supplied as cage liners. It is available in several colours, but the most common colour used is white which assists in observing the animals in the cage microenvironment. Alpha cellulose is a paper-based bedding material with high absorbency and consistent structure, and can be autoclaved. Cotton fibers can be added to paper bedding products to increase their strength and to provide greater absorbency qualities. Some specific paper bedding has been demonstrated to increase activity in laboratory rodents, promoting an enriched environment within the cage.
Wood-derived bedding materials are heat-treated during manufacture to reduce any contaminants and to enhance absorbency. Both corn cob and wood-derived bedding are normally aspirated to reduce the dust load, and microbiological analysis normally accompanies shipments to the facility. It’s important to note that pine products are known to induce liver drug-metabolising enzymes, which can be a major variable in any experimental analysis. Some wood-derived bedding materials can alter endocytosis, a process whereby a substance gains entry into a cell without passing through the cell membrane. Cedar-derived wood bedding materials have also shown to have a dramatic effect on liver enzymes in some laboratory species.
ALLERGENS
Choice of bedding is important as some types of bedding materials can act as dust contaminants and are predisposed to the spread of organisms within and throughout a facility. Simple microbiological analysis that detects the number of colony forming units (cfu) within a sample will ultimately assist in bedding choice. This is also important for the safety of personnel caring for the animals in terms of occupational exposure limits to bedding (dust) materials and the implication of these materials in contributing to laboratory animal allergy (LAA).
CAGE CHANGES
The number of cage changes required depends on the bedding choice that is made. With some bedding substrates, there is a very short time period before animal cages need to be changed, and with others a significantly longer time period—up to 14 days in some instances. However, close observation needs to be maintained to check that increased ammonia levels are not apparent which may affect the cage occupants.
STORAGE
The receipt and storage of bedding materials into the animal facility is of paramount importance to ensure no contamination. Shavings, corn cob, and other similar bulk products should be securely wrapped/bagged and must be received clean. These are normally held within a peripheral location before being introduced into the facility via an autoclave, and distributed to work areas for use.
CONCLUSION
Bedding for laboratory animals may appear a mundane and unimportant issue for some people, but it is very important and is perhaps the single major factor which contributes to the overall welfare and wellbeing of the animals in your care.
Good choice of bedding for your research animals requires careful consideration. The success of your choices will undoubtedly contribute and translate in a positive manner to your research.