Animal Research in Numbers 2020

In 2020, 68,398 animals were used in total at the University of Zurich, 66,573 for research and 1,825 for education purposes. This represents a decrease of 3.6% compared to the previous year. The most commonly used animals were mice (79%), amphibians (9.8%) and rats (2.6%).

Nearly eight out of 10 of the animals used in 2020 at UZH were mice – around 54,043 in total. The second most commonly used animals, but much fewer, were 6,722 amphibians (mainly larvae), 1,810 rats, 1,549 snow voles, 1,350 fish and 760 pigs. All other animal species or groups counted together made up 3.2% of the animals used. Less than 1% of the total animals used were animals commonly kept as pets (dogs and cats), and 2.6% were farm animals (pigs, cows, horses, chickens, sheep and alpacas).

Research involving animals in Switzerland is divided into four degrees of severity (DS) that measure distress or constraint, from 0 to 4 (DS 0, DS 1, DS 2 and DS 3). 29.6% of the animals used at UZH in 2020 were used in experiments that caused little distress, and 36.4% in experiments that involved no distress. 29.9% of animals were used in experiments causing moderate distress, and 4.2% in experiments causing severe distress.

Degree of severity 0 (DS 0): No constraint

If an animal experiences no pain, suffering, injury or fear during an experiment, the degree of severity is classed as 0.
These kinds of experiment might involve, for example, observing behavior to research social and cognitive abilities of squirrel monkeys and common marmosets. For larger animals, such as dogs and cows, taking blood samples is included in this category. At UZH, 29.6% of the animals used in 2020 fell into this category.

Degree of severity 1 (DS 1): Slight constraint

Degree of severity 1 includes research projects in which the animals experience brief slight pain or injury or slight impairment of their general state of health. If laboratory animals are anesthetized and killed in order to remove tissues or organs from them – e.g. to obtain a cell culture – the degree of severity is also classed as 1.
For example, if an animal is fitted with a permanent catheter in an outer blood vessel or a skin tissue sample is taken, the degree of severity is classed as 1. In 2020, 36.4% of the animals used in UZH research projects were in this category.

Degree of severity 2 (DS 2): Moderate constraint

If the constraints in an experiment are moderate but brief, or if they are slight but last longer, the degree of severity is classed as 2. Such experiments include repeatedly taking blood samples under short-duration anesthetic or surgical interventions under anesthetic which, despite pain treatment after the operation, cause pain, suffering or impairment of the animal’s general state of health.
At UZH, for example, sheep are sometimes used in studies with degree of severity 2 to research ways to improve healing of tendons, cartilage and bones. Other research, for example, is concerned with developing vaccines against toxoplasmosis – an infectious disease which frequently occurs in cats. In 2020, a total of 29.9% of animals used in experiments at UZH were in this category.

Degree of severity 3 (DS 3): Severe constraint

If the experiments cause the animals severe pain, ongoing suffering, severe fear or severe impairment of their general state of health, or if the constraints are moderate and medium-term or long-term, they are classed as degree of severity 3.
Experiments with the highest degree of severity usually involve mice or rats. They are used to research severe, complex diseases such as cancer, epilepsy, Alzheimer’s, multiple sclerosis and other auto-immune diseases, or organ transplants and infectious diseases. In 2020, 4.2% of the animals used at UZH were involved in studies that fell into this category.