Grant: Discovery Grants Program - Individual

Environmental factors play a crucial role in the welfare of animals. We have previously demonstrated that different housing scenarios, rearing environments and handling protocols influence the behavior and physiology of rats; however, there are additional environmental factors influencing animal welfare that are not apparent. Sensory capacities, including hearing, vary across species, dictating a unique experience. In some animals, hearing as well as communication extend well beyond the capacity of humans. Through our analysis of ultrasonic vocalizations (sounds used by rats to communicate that are of a frequency too high for human perception), we have discovered that the laboratory space is polluted with aberrant environmental ultrasound that is of high amplitude and variable frequency. Our preliminary analysis indicates that other animal occupied spaces including houses and farms also have a high volume of ultrasounds audible to the occupants. Critically, these ultrasounds do not appear to be innocuous. Our preliminary results have found that exposing adult rats to an identified laboratory ultrasound over a moderate period of time influenced affective behavior and related physiology. The results of this work are concerning, pointing not only to a potential welfare concern but also representing a major contributor to the scientific replicability crisis; however, the impact of ultrasound remains largely unknown and must be better characterized. As a means of further understanding the impact of ultrasound, we propose to further study the effects of various ultrasounds on adult rats. Ultrasounds of different frequencies likely have varying effects on rats given their use in communication. Additionally, the effect of ultrasound exposure over various durations may have diverse outcomes, for example, continuous ultrasound exposure versus short, intermittent exposure. It is further possible that developmental exposure to ultrasound could result in persistent behavioral and physiological changes as seen with other developmental perturbations. In these circumstances, ultrasound could alter the results of an experimental intervention; these potential scenarios will also be explored within this proposal. Lastly, as a means of better understanding the pervasiveness of ultrasounds within the environment, various animal occupied spaces will be surveyed and assessed for the presence of ultrasound leading to potential mitigation strategies. This research program will provide a comprehensive understanding of the prevalence and impact of environmental ultrasounds setting the stage for this novel area of study and informing scientists and the public alike of potential risks and developing mitigation strategies.