Animals, Stock Density, and Bedding

Mature male animals have been shown to generate higher concentrations of allergen in urine40,44 and in animal rooms.66 A recent study suggests that working with male animals may increase the risk for LAA.22 If it is feasible, considering the scientific question at hand, substitution with younger or female animals is likely to reduce aeroallergen levels and possibly LAA.

Several studies have shown an association between stock density and allergen levels (see Figure 7.4).17,57,60,63 The usefulness of this information is slight, as density is much more likely to be dictated by business factors. The advent of individually ventilated cage systems now means it is feasible to increase stock density while maintaining control of ambient levels of aeroallergen.69 However, the allergen and potentially pathogen-releasing cage-changing task still requires practical solutions to minimize contamination.

Bedding has an influence on allergen concentrations, although other factors, such as toxicological implications for the animals, will also influence the choice. Absorbent pads are associated with lower allergen levels than wood chips or sawdust (see Figure 7.5).17 Wood chips give lower aeroallergen concentrations than sawdust.71 Crushed corncob was found to give lower levels than wood shavings.66 The impact of animal cage enhancements on allergen exposure has not been reported, however, preliminary findings suggest that enrichment measures may increase allergen levels during cage changing.72


Animal facilities should be designed so that they can be effectively and safely cleaned. Examples of this are the use of closed vacuum cleaners that deliver dust into a closed-pipe conveyor with deposition into a sealed container, the use of moist mopping, or damp sweeping. Dry-cleaning procedures, such as c

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