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Housing conditions for laboratory animals can affect animal well-being and experimental results. There are guidelines for laboratory animal husbandry but these are insufficiently based on objective research and thus may not reflect the actual needs of the animals. In order to evaluate housing conditions for laboratory mice, we developed a non-invasive preference test system. The possible application of the multiple-choice housing system is as follows. Individual mice can be offered different housing conditions in different test cages. During the test period the movements of the mice between the test cages can be detected automatically. Simultaneously, behaviour of the animals can be recorded with a mouse-directed video system. When interpreted with caution, combined analyses of relative dwelling times and animal behaviour can give information on the preference of mice for the housing conditions under study. The results can advance the selection of proper housing conditions for laboratory animals. In this paper, a detailed description of our preference test system is given and its validity discussed.

The type of bedding material has been reported to affect the environment in both the animal cage and animal room. It has an impact on the health and well-being of the animals and may cause biased experimental results. Requirements for bedding materials, particularly those regarding animal comfort are poorly supported by experimental data. In this study, various types of bedding material were evaluated using preference tests with mice and rats. It was found that beddings consisting of relatively small particles (-1.2 × 1.6 mm2) were generally avoided, whereas beddings consisting of large fibrous particles were preferred. The characteristics of the bedding materials were further investigated by scanning the size and shape of the particles, and by the assessment of ultrasound produced by the moving of the beddings. The results seem to indicate that size and manipulability are among the main determinants of the appreciation of bedding particles by laboratory mice and rats, and larger particles are preferred.

The enigmatic veil associated with the cattle parasite Haematoxenus veliferus has been shown to be crystallike in ultrastructure and to stain with benzidine like haemoglobin. The ultrastructure of the organism is similar to that of other theilerial parasites. As less distinct veil-like structures are known to occur with some other Theileria species, and, in one case, have also been shown to be crystalline in structure, it is proposed to sink the genus Haematoxenus as a synonym of Theileria.

Longitudinal structures in red cells in Giemsa-stained blood smears of goats in the Netherlands were indistinguishable from what has been described as Mukherjeella caprae Bandaranayake and Neitz, 1961 (Rickettsiales). Electron microscopic studies and animal experiments showed, however, that these structures are not parasitic in nature, but are fibres consisting of bundles of microfilaments embedded in the erythrocytic cytoplasm, apparently identical with the longitudinal fibres in goat erythrocytes which are considered to be a haemoglobin abnormality. The condition appears to be genetic. M caprae should be considered as a nomen dubium.