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Could measuring ultrasonic vocalisations help refine rat welfare?

Rat by two bowls filled with plastic pieces

Press release issued: 19 September 2023

Listening to rats' ultrasonic vocalisations could help provide a method to measure the impact of potential refinements on rat welfare without needing to remove the animals from their home cage.

The study, led by Emma Robinson, Professor of Psychopharmacology at the University of Bristol, has been awarded funding of over £500,000 by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) for the new research.

Studies suggest that adult rats make ultrasonic vocalisations at different frequencies when they experience positive or negative events. It has not previously been possible to confirm this, but a novel method developed by the Robinson group provides an objective way to now achieve this.

In the funded research, the group will find out whether two refinement approaches lead to more positive welfare and whether this is reflected in the animal’s vocalisations. This will provide proof-of-concept and whether this approach can be used to understand rat welfare.   

Animal research requires that studies consider the 3Rs (Reduce, Refine and Replace).  Refinement involves using methods which cause the least suffering to the animal, and this can be more challenging to assess objectively.  To achieve refinement requires the ability to quantify the animals affective or 'emotional' experience.

Professor Robinson said: "We hope our study will show that by measuring rats' ultrasonic vocalisations it will provide a simple and easy to use method to evaluate refinements.  Our approach will not require costly equipment or specialist expertise meaning it could be readily set-up and utilised within any animal research facility."

It can be challenging to objectively measure whether changes to housing and husbandry positively impact animal welfare, particularly when the refinements are intended to improve the animal’s emotional state. Investigating emotional state typically requires animals to be removed from their home cage to undergo complex behavioural procedures. 

This study aims to establish whether vocalisations are a way of understanding a rat's emotions.  These validation studies will show whether recording animals calls can provide information about their emotional state both during acute experiences and in relation to core affect or 'mood'.  

Habituation to human handling and a novel caging system designed to increase space and social interactions whilst also being practical for handling are the two refinement methods the research will study.  It is hoped outcomes from the research will be methods to enable many more researchers to study refinement and allow institutions to monitor the emotional state of their animals using a simple, non-invasive and non-specialist method.

Research carried out at Bristol has already pioneered the development of objective methods to measure animals' affective state.  By translating behavioural methods from human psychology, new procedures have been developed and validated that accurately measure animals positive or negative emotional experience of different interventions.  One of these procedures, the affective bias test, has been used to show that high frequency calls emitted by rats provide a graded measure of their individual emotional experience.

Research study 'Could ultrasonic vocalisations provide the elusive, graded measure of affective state needed to inform refinements For The Laboratory Rat?' has been awarded funding of £565,942by NC3Rs.  The three-year project will begin in December 2023.

Further information

Paper that led to the NC3Rs grant: 'Rat 50kHz calls reflect graded affective responses' by Justyna Hinchcliffe et al. in Current Biology

Find out more about research involving animals at:

About National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs)
The NC3Rs is a UK-based scientific organisation that works nationally and internationally with the research community to replace, refine and reduce the use of animals in research and testing.



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