The Effects of Water Volume and Bacterial Concentration on the Water Filtration Assay Used in Zebrafish Health Surveillance.

The number of zebrafish in biomedical research has increased exponentially over the past decades, leading to pressure on the laboratory animal community to develop and refine techniques to monitor zebrafish health so that suitable stocks can be maintained for research. The water filtration assay is a promising technique in which water from a zebrafish system is filtered, and the filter analyzed by PCR. In the present report, we studied how the volume of water tested and the concentration of bacterial pathogens affected test results. To do so, we used stock solutions of 3 zebrafish pathogens: Edwardsiella ictaluri, Aeromonas hydrophila, and Mycobacterium marinum. We used these stocks to create solutions with known concentrations of each pathogen, ranging between 10² and 107 Colony Forming Units (CFU) per ml. One, 2, and 3 L of each solution was filtered using positive pressure, and the filters were submitted to a commercial lab for PCR testing. Results were fit with a logistic regression model, and the probability of obtaining a positive result were calculated. Test sensitivity varied by organism, but in general, test results were positively correlated with the volume of the water filtered and with the concentration of bacteria in solution. We conclude that a positive result can be expected for E. ictaluri at 105 CFU per mL, A. hydrophila at 106 CFU per ml, and M. marinum at 106 CFU per mL, when 3 L of solution are filtered.

Hemochromatosis in Two Female Olive Baboons (Papio anubis).

This report describes hemochromatosis associated with chronic parenteral iron dextran administration in 2 female olive baboons (Papio anubis). These baboons were enrolled on an experimental protocol that induced and maintained anemia by periodic phlebotomy for use in studying potential treatments for sickle cell anemia. The 2 baboons both presented with clinical signs consistent with iron overload, including decreased appetite, weight loss, elevated liver enzymes, and hepatosplenomegaly. Histopathologic findings supported a morphologic diagnosis of systemic hemosiderosis, as evidenced by the overwhelming presence of iron in the reticuloendothelial system and liver after the application of Prussian blue stain. This finding, combined with the clinical presentation, lead to a final diagnosis of hemochromatosis. This case report suggests that providing anemic patients with chronic parenteral iron supplementation in the absence of iron deficiency can result in iatrogenic iron overload and subsequent systemic toxicity. Furthermore, these subjects may present with hemochromatosis and its associated clinical signs many years after cessation of iron supplementation.

Behavioral Effects of Cage Size and Environmental Enrichment in New Zealand White Rabbits.

One of the goals of environmental enrichment is to encourage species-typical behaviors, while discouraging abnormal behaviors or stereotypies. Assessing the effectiveness of various enrichment modalities can be challenging, particularly for prey species such as rabbits that exhibit freezing responses in the presence of people. In this study, we housed rabbits in 3 different sized cages and observed their behaviors. The 3 cage sizes were our standard rabbit housing cage, a medium sized cage, and a large run. Based on analysis of the recordings, ethograms were constructed and behaviors were quantified. The rabbits in large runs spent more time performing active, exploratory behaviors (431 ± 74 s) than rabbits in the standard cages(184 ± 55 s). However, space constraints inside research facilities often make it impractical to house rabbits in large runs.Therefore, we decided to explore if enrichment devices could promote the expression of active behaviors, similar to those displayed by rabbits housed in the large runs. We selected 3 devices: a hanging toy, a destructible device, and a dig bin. All 3 enrichment devices promoted more time spent performing active, exploratory behaviors (389 ± 48, 463 ± 50, and 420 ± 44 s,respectively), compared with control rabbits housed without an enrichment device (226 ± 53 s). We also analyzed the fecal glucocorticoids of rabbits after shipping or surgery to determine if enrichment devices could mitigate the physiologic impact of these stressors. We found no significant differences in fecal glucocorticoid levels between rabbits that experienced the stressor and rabbits that did not, or between rabbits with or without enrichment devices. Overall, the provision of largercaging and/or addition of enrichment devices encouraged a broad spectrum of active, species-typical rabbit behaviors, suggestiveof improved animal welfare.