Auditory brainstem response in pigs: normative data and insights from TPC2 knockout models

Pigs are increasingly used as translational models for auditory research due to anatomical and physiological similarities with humans. However, normative auditory brainstem response (ABR) parameters in commercial pig breeds remain poorly characterized, limiting their use in hearing research and genetic models.

To establish reference ABR values across stimulus intensities in pigs and assess the influence of genotype, age, and sex, including the evaluation of TPC2 knockout (KO) animals.

ABR recordings were obtained from 42 pigs (wild-type, heterozygous, and TPC2KO) under under controlled anesthetic conditions. Click stimuli (90-10 dB nHL) were presented via insert earphones. Latencies and amplitudes of waves I-VI, interpeak intervals, and detection thresholds were analyzed using repeated-measures ANOVA and linear mixed-effects models. Machine learning approaches were used exploratorily to assess potential non-linear relationships among variables.

Peak detection and amplitude decreased with lower intensities (P < 0.001), while latencies increased. Wave V remained detectable at all intensities, with a mean threshold of 33.6 ± 2.7 dB nHL. No significant differences were observed between ears or across genotypes and sex. Age influenced the I-III interpeak interval (P < 0.05) but not individual wave latencies or amplitudes. Machine learning analyses identified age as the most relevant contributor to ABR variability among tested factors.

This study provides normative ABR reference values for pigs, defining normative values across intensities and demonstrates the absence of detectable click-evoked ABR alterations in TPC2KO animals under the present conditions. These findings support the use of pigs as robust models for auditory research and genetic studies of hearing loss.