Smarter monitoring, fewer animals

The Joint Animal Laboratory (GDL) of Utrecht University and UMC Utrecht has switched to a new screening method for monitoring the health of mice and rats in the laboratory. This innovative approach makes it possible to accurately monitor the animals’ health without the need for live animals.

The Joint Animal Laboratory (GDL) of Utrecht University and UMC Utrecht has switched to a new screening method for monitoring the health of mice and rats in the laboratory. This innovative approach makes it possible to accurately monitor the animals’ health without the need for live animals.

With the new screening method, pathogens (disease-causing agents such as bacteria, viruses, or fungi) are efficiently detected via filters that come into contact with the bedding material. As a result, the use of so-called sentinel animals (animals deliberately used to check for the presence of pathogens) is no longer necessary. By repeatedly exposing the filters to the soil material over a three-month period, a complete picture emerges of both the current and past presence of these pathogens.

Decline to zero

The impact of this change is clearly visible in the figures. Whereas in 2016, 287 mice and 61 rats were still used for health monitoring, this number has dropped to zero since March 2026. “By working smarter and more innovatively, we can improve the care of laboratory animals while simultaneously reducing the number of animals required to zero”, says Marian Verhage, manager of the GDL.

“The GDL is continuously working to foster a strong Culture of Care,” adds Pascalle van Loo, head of the Animal Welfare Body Utrecht. “Animal welfare and the 3Rs are central to all aspects of our operations, and innovation is paramount in this regard. This makes the GDL an example for other animal facilities.”

About the GDL

Research and education involving laboratory animals take place at the GDL. In addition to housing and caring for the animals, expert biotechnical support is provided, and staff members are engaged daily in the (cognitive) training of the animals. Last February, several of them even won the Culture of Care Award for this.

World Day for Laboratory Animals

On World Day for Laboratory Animals, we reflect on the use of laboratory animals in research and education, as well as on the ongoing efforts to reduce, refine, and, where possible, replace this use. And that every step toward reducing and improving the use of laboratory animals counts. The transition to this new screening method is a fine example of that.