Severity Assessment from the Animal’s Point of View

In Germany, researchers conducting animal experiments are required to assess the burden that animals may experience in relation to the experimental procedures. An essential part of the approval procedure by the authorities is to examine the researcher's assessment of the severity of the experiment.

In fact, the severity assessment in animal experiments is a complex ethical and biomedical challenge, and the demands on laboratory animal science regarding severity assessment are steadily increasing. Interpretation of behavioral data and physiological parameters related to animal welfare is sometimes insufficient for a valid severity assessment. Of particular importance are scientifically verifiable methods in order to be able to assess the burden from the animals' point of view.

Development of preference tests

The Bf3R is working on the development of preference tests using the choices of the animals themselves to assess burden. Furthermore, researchers at the Bf3R examine if animal experiments measurably affect the emotional state of laboratory animals. Emotional states in laboratory animals can be tested by using the cognitive bias test. The methods proposed here aim to assess burden from the animals' perspective by including their preference and their cognitive bias. 

Humans as well as animals make a large number of decisions throughout their lives. Even though many of these decisions are made unconsciously, they are closely linked to moods and emotions. A positive mood leads to an optimistic expectation of future events and thus to different decisions than a pessimistic mood. In this context, the concept of cognitive bias describes how decisions depend on the expectation of future events. A few years ago, experimental procedures were first presented on how to study "cognitive bias" in animals. The basic principle is to train the animals to expect a reward for a given stimulus (Figure 1) and to expect a punishment for another stimulus (Figure 2). For the training, scalable stimuli (e.g., sounds, grayscales, odors) are used represented by colored boxes in the figure, with the reward conditioned at one end of the scale and the punishment conditioned at the other end of the scale. After successful conditioning, animals are presented with ambiguous stimuli that are calibrated between the positive and negative conditioned stimuli (Figure 3). By observing whether the animals rather expect a reward or a punishment in this situation, the cognitive bias can be systematically investigated. In this way - anthropomorphically formulated - pessimistic and optimistic animals can be distinguished.

Further reading:

Habedank, A.; Kahnau, P.; Diederich, K.; Lewejohann, L. Severity assessment from an animal’s point of view. BMTW 2018
https://doi.org/10.2376/0005-9366-18007

Kahnau, P.; Habedank, A.; Diederich, K.; Lewejohann, L. Behavioral Methods for Severity Assessment. Animals 2020, 10, 1136.
https://doi.org/10.3390/ani10071136