Hearing and Cochlear structures in a Swine Model

ObjectiveTo study the audition and inner ear structure in a normal swine model.MethodsAuditory brainstem responses (ABRs) were determined in swine at 1 day and 1 month after birth. The form of the cochlea and hair cells were examined under a scanning electron microscope and on cochlear slices.ResultsABR thresholds at 1 day and 1 month post–birth were between 40 and 50 dB SPL. The latencies of waves I, III and V in 1 day old swine were 1.97 ± 0.13, 3.01 ± 0.16 and 4.26 ± 0.20 ms, respectively. At 1 month, the lantancies of waves I, III and V were 2.01 ± 0.05, 3.11 ± 0.08 and 4.65 ± 0.14 ms, respectively, slightly longer than those at 1 day, although not statistically significant (p>0.05). The swine cochlea was constituted of 3 and a half turns and the cochlear hair cells lined up in four rows. Hair cell cilia in the apical turn were longer than those in other turns.ConclusionsThe swine cochlea is mature at the time of birth. Swine ABR thresholds are slightly higher than humans and rats. Swine appears to be a precocial animal species.