Auditory brainstem responses in the normal beagle |
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| Authors: | A J Venker‐van Haagen R J G Siemelink G F Smoorenburg |
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| Institution: | 1. Department of Companion Animal Medicine and Surgery , State University of Utrecht , Yalelaan 8, Utrecht, 3584 CM, The Netherlands;2. Laboratory of Experimental Audiology, Department of Otorhinolaryngology , University Hospital , Catharijnesingel 101, Utrecht, 3511 GV, The Netherlands |
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| Abstract: | Summary The latencies of the peaks in brainstem responses and the threshold response were determined in 18 healthy beagles. In the first series of measurements the dogs were sedated and the stimulus was delivered via an in‐the‐ear transducer. The latencies, the threshold levels, and the influence of the stimulus repetition rate on the latencies were measured. Using a miniature electret microphone in the outer ear canal near the tympanic membrane, it was found that at a level setting corresponding to 0 dB human level (HL) the major peak in damped oscillation during condensation reached a sound pressure level (SPL) of about 27 dB and the secondary rarefaction peak reached 24 dB SPL. In the second series of measurements the dogs were not sedated and the stimulus was delivered via a headphone. The wave forms, the mean latencies for peaks I to V as a function of the stimulus level, and the threshold of each wave are presented from both series. In the first series the latency values at 80 dB HL (107 dB SPL) were 1.21, 1.97, 2.67, 3.12 and 3.61 ms for peaks I, II, III, IV and V, respectively. The thresholds for peaks I to V were 47.5 ± 9.5, 47.5 ± 11.5, 41.3 ± 13.0, 63.3 ± 17.4 and 28.0 ± 9.7 dB HL, respectively. The difference in peak latency between the first and the second series was 0.065 ms. This difference corresponded to the difference in length of the acoustic pathways. Analysis of variance was used to determine whether the successive peaks in the response followed at a constant time interval, i.e., whether a shift in the first peak with a change in the stimulus level was followed by the same shift in subsequent peaks. The analysis showed a significant (P < 0.001) interaction between the inter‐peak latency differences and the effect of stimulus level. This inter‐peak latency depended on stimulus level, although the effect was small. The use of the in‐the‐ear transducer and sedation resulted in a far more efficient procedure than the use of the headphone without sedation. |
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| Keywords: | dog canine anaemia haemolysis idiopathic immune-mediated |
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