The mouse passport
The mouse is the most widely applied experimental animal both in Denmark and globally. In diabetes research, which is one of the largest research areas in Denmark, mice are raised with a high fat diet that causes them to develop obesity and a type-2-diabetes-like condition.
How many animals to be used in each experiment are determined by how differently the mice reacts, and how fat or diabetic they become. Recent research has shown that this variation is largely controlled by the gut bacteria of the animals, which today, in contrast to previously, can be relatively easily characterized by a molecular examination of a fecal sample. Another influencing factor may be the animals' DNA.
Although very uniform inbred mice are used, newer methods have shown that the mice in their genetic material outside the actual genes mutate at high frequencies, and that these mutations control the variation of different expressions in the mouse. In this project, each mouse is characterized by their gut microbiota and their genetic material, after which an obesity test is performed with a well-known treatment.
It is determined how much of the variation in the results that can be described using these characteristics, and it is calculated how many animals to use, if such characteristics are available compared to the amount of animals to be used the way experiments are carried out today. In the long run, giving each mouse an individual characterization, a 'passport', will enable such studies with fewer mice, because it may be known which ones are the most or least susceptible to obesity and treatment, and if so it can be taken into account in the data evaluation, and eventually also be possible to select the most suitable mice for the study.