Brainstem auditory evoked potential wave V latency-intensity function in normal Dalmatian and Beagle puppies

This study investigated whether Dalmatian puppies with normal hearing bilat erally had the same click-evoked brainstem auditory potential characteristi cs as age-matched dogs of another breed. Short-latency brainstem auditory p otentials evoked by condensation and rarefaction clicks were recorded in 23 1.5- to 2-month-old Dalmatian puppies with normal hearing bilaterally by a qualitative brainstem auditory evoked potential test and in 16 Beagle dogs of the same age. For each stimulus intensity, from 90 dB normal hearing le vel down to the wave V threshold, the sum of the potentials evoked by the 2 kinds of stimuli were added, giving an equivalent to the alternate click p olarity stimulation. The slope of the L segment of the wave V latency-inten sity curve was steeper in Dalmatian (-40 +/- 10 mu s/dB) than in Beagles (- 28 -/+ 5 mu s/dB, P <.001) puppies, The hearing threshold was lower in the Beagle puppies (P <.05. These results suggest that interbreed differences m ay exist at the level of cochlear function in this age class. The wave V la tency and wave V-wave I latencies differences at high stimulus intensity we re different between the groups of puppies (4.3 +/- 0.2 and 2.5 +/- 0.2 mil liseconds, respectively, for Beagles; and 4.1 +/- 0.2 and 3.3 +/- 0.2 milli seconds for Dalmatians, P <.05. A different maturation speed of the neural pathways is one possible explanation of this observation.