Establishment of an objective endpoint in mice model for caseous lymphadenitis vaccine trials

For a long time, the scientific community has described the need for a continued update in practices that ensure the welfare of animals undergoing experimentation. In addition to approaches on principles of care and use of animals, there is a more current emerging concern: defining an appropriate end point in experiments that use animals for research, teaching and testing. The term "endpoint" is defined as the point at which an experimental animal's pain and/or distress is terminated, minimized, or reduced humanely. In the present study, we established an endpoint in Balb/C mice for caseous lymphadenitis vaccine trials, which can be considered as a highly important parameter since several studies are being developed to control the disease efficiently. Mice were monitored daily until the 30th day after infection with pathogenic strain of C. pseudotuberculosis MIC-6 using the most relevant parameters for the appearance of clinical signs of caseous lymphadenitis (CLA), such as abscesses, lethargy, and loss of weight and hair. The endpoint was found to be a weight loss of 0.2167 g after five days or 10% weight loss in less than five days. In conclusion, the findings reported here will help improve animal's well-being during vaccine trials for CLA and consequently represent significant contribution to animal's welfare.