Jones, T., Robinson, M., Leach, M. et al. 2017. Ultrasonic vocalisation as a measure of positive welfare in rats. Animal Technology and Welfare 16(2), 127-129.

Studies of animal welfare in laboratory animals have historically relied on the measurement of negative indicators rather than the assessment of positive indicators of welfare. Practical methods of welfare assessment are required to allow refinement of housing and experimental protocols. Ultrasonic vocalisation (USV) can be used as a measure of positive and negative emotional state. This poster compares the production of USV in the frequency range associated with positive emotional state in rats (50 kHz) within 2 different cage types and considers the utility of USV recording as a welfare indicator, assessing both its practicality and effectiveness. Increased amounts of positive ultrasound vocalisations (50 kHz) were recorded in the rats housed within the Enriched Cage. Analysis of USV Total Count (AM and PM together) showed a significant increase in USV with time in the Enriched Cage (p<0.01) but not the Standard Cage. These data support our original hypothesis that offering rats the Enriched Cage would have a positive effect on their wellbeing and result in increased USV at the 50 kHz frequency. Compared to the Standard Cage, the human observer can see that the Enriched cage is subjectively “better”. Similarly these data provide objective evidence that the increased space and enrichment provide something meaningful to the rats. USV data can potentially be used to determine emotional state of rats in use on other regulated procedures, for example to objectively measure the effect of refinements to procedures and/or inform decisions on husbandry, care and housing.