Humane Endpoints in Swiss Webster Mice Infected with Toxoplasma gondii RH Strain.

The highly virulent Toxoplasma gondii RH strain is maintained through successive passages in mice, but there is still a lack of studies that refine these procedures from a 3Rs perspective, where humanitarian ideals aim to minimize the stress, pain, or suffering of the animals used in the research without the loss of results. The aim of this study was to establish humane endpoints in Swiss Webster mice inoculated with the T. gondii RH strain. A total of 52 mice were infected with 5 × 106 tachyzoites/mL and monitored for periods of up to 5 days. The parameters body weight; hair condition; higher than normal body temperature; hypothermia; respiratory function; pain; soft stools or diarrhea; bloody diarrhea; tense, nervous, or in distress during handling; and ascites were recorded daily in score tables. The results showed that prominent piloerection, respiratory function, pain parameters, and ascites are important clinical signs to be used as a cut-off point for implementing euthanasia. The application of this refinement method helped to avoid animal suffering and pain without compromising the number of parasites recovered. We therefore suggest adopting these parameters in research protocols that require the maintenance of the T. gondii RH strain in murine models to avoid and reduce animal suffering.

Housing Density and Aggression in Syrian Hamsters.

The Syrian hamster (Mesocricetus auratus) is a solitary and naturally territorial animal, with female hamsters being more aggressive than males. This behavior makes handling difficult because they are usually housed in groups, which can lead to aggressive behavior. The objective of this study was to refine the management of Syrian hamsters in order to minimize aggressiveness, reduce the animal injuries, and lessen the risk of accidents among laboratory animal technicians due to the hamster aggression during handling. The experiment was conducted at the Center for Animals Experimentation, Oswaldo Cruz Institute. Four groups of hamsters were observed by video recording: group 1 (group-housed males, 6 to 8 wk of age), group 2 (group-housed females 6 to 8 wk of age), group 3 (group-housed female, 3 to 4 wk of age), and group 4 (individually housed females, 6 to 8 wk of age). Group 1 animals were less aggressive and agitated both during housing and during handling by the animal technician as compared with groups 2 and 3. Groups 2 and 3 showed greater agitation and aggression. Marked reduction in the level of aggressiveness and agitation was observed in group 4 as compared with all other groups evaluated during handling by the animal technician. Male hamsters housed in groups of 4 and females housed individually have reduced risks of accident during handling, thereby averting distress and consequent physiologic alterations. Avoiding these risks is essential to obtaining reliable experimental results.