Incidence of otitis media in CBA/J and CBA/CaJ mice.

The inbred CBA/J mouse has become a standard experimental animal for auditory study because of its lifelong good hearing. In a newly established mouse breeding colony that housed CBA/J and CBA/CaJ mice to reared as auditory subjects, otitis media frequently afflicted CBA/J mice, reaching an incidence of 90% in animals greater than 400 days of age. Otitis media was not found in CBA/CaJ mice. Three attempts to establish a colony that was free of otitis were unsuccessful. Although the primary pathogen was not clearly established, Pasteurella pneumotropica was isolated from infected bullae. Partial control of otitis media followed the introduction of tetracycline prophylaxis. The CBA/CaJ mice may be suitable replacements for CBA/J mice in studies that require inbred mice with good hearing, since their auditory thresholds did not differ significantly from those of otitis-free CBA/J mice.

Response of adult New Zealand white rabbits to enrichment objects and paired housing.

Enhancing the psychological well-being of laboratory animals has received much attention recently. Although many studies have been undertaken to determine the effects of cage enrichment techniques on dogs and nonhuman primates, other than scant empirical observations, little has been done to measure these events objectively in lagomorphs. We studied adult female New Zealand White (NZW) rabbits to learn if, when given the opportunity, individual rabbits would use different enrichment objects placed in their cages, and to determine if rabbits preferred to be in proximity to one another, or apart. Three different objects were evaluated with eight rabbits individually housed in conventional cages. Each object introduced into individual rabbit cages stimulated substantial interaction, especially chewing behavior. Eight other rabbits were pair-housed in a modified caging system with a special access port between two separate cages. When given a choice, rabbits preferred to be in the same cage with other rabbits. In both studies, individual behaviors were monitored, as well as either the type of interaction and percentage of observations spent with each object or, in the housing study, percentage of observations involved with different types of activity, and relative location of the paired rabbits.

Does the intestinal microflora synthesize pyrroloquinoline quinone?

Pyrroloquinoline quinone (PQQ) functions as a cofactor for prokaryotic oxidoreductases, such as methanol dehydrogenase and glucose dehydrogenase. When chemically-defined diets without PQQ are fed to animals, lathyritic changes are observed. In previous studies, it was assumed that PQQ was produced by the intestinal microflora; consequently, antibiotics were routinely added to diets. In the present study this assumption is tested further in mice by: (i) examining the effects of dietary antibiotics on fecal PQQ excretion, (ii) isolating the intestinal flora to identify bacteria known to synthesize PQQ and (iii) determining in vitro if the intestinal microflora synthesizes PQQ from radio-chemically labeled precursors. The results of these experiments indicate that little if any PQQ is synthesized by the intestinal microflora. Rather, when PQQ is present in the intestine, the diet is a more obvious source.

Effect of shipping stress on clincopathologic indicators in F344/N rats.

A variety of hematologic, serum chemistry, and cytochrome P450 variables from 20 F344/N rats were measured and analyzed statistically to determine the effects of shipping stress on clinicopathologic indicators. Additionally, whole body, liver, and total kidney weights were recorded and compared. Ten rats were assayed upon receipt (stressed group), and 10 additional rats were held on a wire substrate for 12 days (poststress group) and assayed. Significant differences were detected between the 2 groups in ratio of total kidney weight to body weight, segmented neutrophil count, monocyte count, eosinophil count, and serum cholesterol, serum potassium, serum aspartate transaminase, and serum lactate dehydrogenase values.

Evaluation of the control of Myobia musculi infestations on laboratory mice with permethrin.

The efficacy of permethrin against Myobia musculi (Schrank) (Acari:Myobiidae) infestations on mice was evaluated using four different dose delivery methods. In all methods, an attempt was made to deliver 0.5 mg of active permethrin weekly to each mouse. Successful control was achieved with topical or environmental treatment with 0.25% permethrin dust and by dipping the mice into a 0.6 g/l permethrin emulsion. The use of an emulsion applied to the bedding produced the least satisfactory control. Untreated mice had an average infestation rate of 57.3% throughout the study. No significant differences were seen between treated and untreated groups in either body weight or histopathology of the liver, lung, or kidney.