English summary

This is the English summary of the 2023 Annual Report on Animal Experiments by Utrecht University and the University Medical Center Utrecht (UMC Utrecht). It provides information about the use of laboratory animals by the two institutions.

This publication was prompted in part by the Dutch Code for Transparency in Animal Testing. It is one of the many tools we use for being transparent about experiments on animals. For example, there are the very informative websites of the Animal Welfare Body Utrecht, the Animal Ethics Committee Utrecht and the 3Rs Centre Utrecht.

Accountability

At Utrecht University and UMC Utrecht, research in the life sciences (both veterinary and medical-biological) is carried out. Animal experiments are conducted in addition to experiments based on, for example, cell and tissue culture techniques, computer simulations and experiments on human volunteers. Laboratory animals are also used for education and training. All animal use is performed with great care, under supervision of the Animal Welfare Body Utrecht.

Not, unless...

The Dutch Experiments on Animals Act (2014) stipulates that animal experiments may only be carried out if there is really no other option ("not, unless..."). That is, only if there is no animal-free way to achieve the same goal (Replacement). The point of departure is that animals can experience positive and negative emotions and have an intrinsic value. If animal use is inevitable, it is mandatory to see whether that animal experiment can be improved with respect to Reduction of the number of animals and Refinement by, for example, improvement of housing, supervision and procedures. This rule has been elaborated into a set of requirements and steps to take.

From idea to animal experiment

Figures

The number of laboratory animals does not equal the number of animal experiments, since on the one hand animals have been re-used in other experiments, and on the other hand animals were bred as laboratory animals without being used in experiments. Both numbers are kept as low as possible.

i i i

Number of animal experiments

Purpose

59% of the animal experiments were conducted for fundamental research: research into processes, such as research into the functioning of organs. In fundamental research, the way research outcomes will be applied is not yet clear. 25% was conducted for applied research and translational research. Applied research is research that is directly aimed at an application, for example a specific medical therapy. Translational research connects fundamental and applied research, and often includes translation from results of animal research to clinical application for humans. Finally, laboratory animals are used in education and training, for example in veterinary and laboratory animal science courses (14%). About 2% related to breeding of animals with a harmful phenotype.

Animal species

For each research project, the most suitable animal species is used. Around two-thirds of the experiments are conducted with mice. In addition to mice, rats were also used frequently. Other animals used in experiments and education are chickens, pigs, cattle, horses, zebrafish, pigeons, dogs, cats, sheep, rabbits, goats and ferrets.

Bred but not used

Utrecht University and UMC Utrecht are doing their utmost to minimize the number of animals killed without being used for research or education. In 2023, 10,487 animals were killed without being used. 6,327 of these have been used for breeding purposes. The other 4,160 involved animals not suitable for experimental purposes because of gender, age, genetic profile or health problems.

Discomfort

Discomfort is the legal term for all negative experiences that laboratory animals experience through animal experiments. It is mandatory to classify discomfort into the categories of mild, moderate and severe discomfort, or non-recovery (the animal dies during anesthesia having had no previous discomfort). A permanent effort is being made to keep discomfort levels as low as possible.

Mild: 51%
Moderate: 41%
Severe: 5%
Non-recovery: 3%

Rehoming

In mid-2019, a pilot was started in collaboration with animal welfare organizations to explore the options of rehoming rodents in a responsible manner, taking into account the safety, welfare and health of humans and animals. This is now standing policy. Many of the redundant rodents are bred as laboratory animals, but have not actually been used for animal testing. Genetically modified animals are excluded on grounds of legislation. In 2023, 189 rats and twelve animals from other species found a new home.

Trend in the number of animal experiments

Over the period 2001-2023, the number of animal tests performed by Utrecht University and UMC Utrecht decreased from 51,900 to 14.192. Especially in the period 2010-2014, there was a substantial decrease in the number of animal experiments. After several years of stagnation, another sharp decline is now visible. The number of mice and rats shows a steady decreasing trend from 15,595 to 12,108 in the period 2015 - 2023 (the period in which the amended Animal Experiments Act is in force). Because the number of animal experiments is relatively low, fluctuations in experiments in which large numbers of animals are used may have a greater effect on the total. For example, in 2020 and 2021, the number of animal experiments involving zebrafish increased, and in 2022, the number of chicken experiments was relatively high due to an experiment involving broilers. No such large-scale experiments were conducted in 2023, so the overall decreasing trend is now clearly visible.

Trend animals used in education

Since 2015, the number of animal experiments for education has decreased by 68% from 6,230 to 1,984. This is a result of an active policy to reduce animal testing for education wherever possible.