Objective measurements of welfare in rats

Sofie Kromann, Tenure track Assistant Professor, DVM, PhD, ECVP resident

Rats are widely used as animal models in drug development and toxicology, and according to the legislation, animal welfare should be given the highest priority. To ensure good animal welfare, a given species' natural needs and preferences must be considered. Thus, rats should be socially housed and have sufficient and complex space that offers the possibility to actively perform a wide range of species-specific behaviours such as climbing, jumping, playing, huddling, hoarding and exploring. Moreover, rats should live in larger groups and be allowed to segregate areas for sleeping from lavatory areas.

Traditional standard cages only fulfil these criteria to a very limited extent. Better options have become available, allowing the animals to express a wider range of species-specific behaviours. Hence, these alternative cage systems must be expected to markedly improve animal welfare – but how do we measure and quantify this improvement and, thereby, pave the way for a broader implementation of housing systems that facilitate the expression of species-specific behaviours?

In a recent study, housing in an enriched environment – allowing the expression of a wide behavioural repertoire – was compared to standard housing with a focus on performance in

behavioural tests. During the study, great care was taken to ensure a maximised output through extensive collection of additional materials.

With support from the Danish 3R-center, we wish to use materials (tissue and blood samples) from this already-conducted study to identify parameters (e.g., hormones and signalling molecules like monoamines, brain-derived neurotrophic factor (BDNF) and oxytocin) suitable for objectively evaluating and quantifying welfare in rats. Utilising material from this study reduces the number of animals required to generate valuable data and can, concurrently, provide data that encourages a future with a greater focus on providing research animals with the opportunity to perform species-specific behaviours.

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