BAER hearing test: Principles of operation and interpretation for dogs and cats

The nervous system of animals is a focus of interest of multiple research centres. The evolution of medical engineering, the development of new research techniques and the improvement of existing ones increase our understanding of the nervous system. One of the diagnostic methods which can be used to help detect hearing disorders of varying severity in animals and humans is the study of brainstem evoked potentials known as BAER (brainstem auditory evoked response), BAEP (brainstem auditory evoked potentials) or ABR (auditory brainstem response). Although this method has existed for decades and is used in many countries around the world, the knowledge gathered by doctors over the years lacks proper systematization, and neither standard parameters nor a coherent implementation strategy have yet been established. Various modifications of this method are also available, which suggests directions for further research and facilitates an increase in the pool of knowledge concerning the physiology of hearing. Unfortunately, the lack of established recommendations for the practical implementation of hearing tests using the BAER method makes it difficult to compare test results and to broaden the scope of application of this method in dogs and cats. For the most part, this problem results from a random selection of test parameters by researchers who do not have sufficient knowledge about the physics of hearing. This work aims to summarize the results obtained in this field by various authors around the world and to determine the best-performing variants of the BAER method. The optimization and systematization of the parameters not only increases the reproducibility of the results and makes them more transparent and uniform for both doctors and animal keepers, but also renders them more reliable. This could aid in the creation of a worldwide database resulting in beneficial outcomes over time and may also allow veterinarians to determine the most effective approach for conducting a study depending on many variables that need to be taken into account.