Breegi, S. 2011. Evaluation of nesting materials for use in nude mouse colonies. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 782 (Abstract #P171).

Nesting material has been reported to be beneficial to mice by providing environmental enrichment as well as a means of thermoregulation. Cotton nesting material has been reported to cause conjunctivitis in athymic nude mice. We evaluated 3 different paper-based nesting materials to determine the optimal nesting material for our nude mice housed in individually ventilated cages with wood chip bedding. Tissue paper nesting sheets, twisted white paper bedding, and shredded brown paper were evaluated. Cages were provided with either 4 nesting sheets, 8 g of twisted white paper bedding, or 8 g of shredded brown paper. One hundred and twenty-five CD1 Nu/ Nu mice (housed 5 per cage) were housed with each product for 2 wk, using a crossover study design. Ammonia levels were monitored in all cages on days 0, 7, and 14 of the cage change cycle. Nesting material was evaluated daily for usage and any nests built were scored using a 5-point naturalistic scoring scheme. The mice were examined daily for the development of any clinical health complications including conjunctivitis and fight wounds. Each product was also pre-evaluated for low dust production and compatibility with our vacuum bedding disposal system. Nests made with shredded brown paper scored highest (average nesting score: 2.8 ± 0.37), followed by the tissue paper nesting sheets (2.3 ± 0.41) and the twisted white paper bedding (2.0 ± 0.08). All animals interacted with each of the nesting materials to some extent. No nesting material produced a measurable amount of ammonia. No adverse health effects were noted during the study. A few other criteria for our final selection were realized during the study. The tissue paper nesting sheets, for a large scale operation, would be the easiest to sterilize and dispense, in comparison to the other nesting materials. The smaller space required to store the tissue paper nesting sheets would be beneficial in our animal facility. The nests created with shredded brown paper had high, thick walls making cage-side health observations by the veterinary staff difficult to conduct. Taking all factors into consideration, the tissue paper nesting sheets are the most suitable nesting material for use with nude mice in our animal facility. Tissue paper nesting sheets appear to strike the best balance between animal use, ease of visual observations, and ease of storing and husbandry duties.