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Deafness testing in dogs: optimisation of the brainstem auditory evoked response (BAER) protocol and investigation of otoacoustic emissions as an alternative technique

Goncalves, Rita (2012) Deafness testing in dogs: optimisation of the brainstem auditory evoked response (BAER) protocol and investigation of otoacoustic emissions as an alternative technique. MVM(R) thesis, University of Glasgow.

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Abstract

The first formal descriptions of deafness in the dog were already made over 100 years ago, and in the intervening period our understanding of canine deafness has improved dramatically. The most common type of deafness encountered in the domestic dog is congenital sensorineural deafness, which has now been reported in over 80 canine breeds and is usually associated with white pigmentation and blue eye colour. The correct identification of congenital sensorineural deafness is important as it allows the selection of breeding animals to reduce transmission of this trait to future generations. In other forms of hearing loss, deafness testing may help to inform the severity and often the underlying cause of the hearing impairment. The brainstem auditory-evoked response (BAER) is the most commonly used test for assessing auditory function in dogs. Despite its widespread use, variables have been shown to affect the BAER in human patients which may result in reduced test reliability, and which have not been fully investigated in dogs. One such variable that may complicate test interpretation is the crossover effect. In Chapter 3, I demonstrate that the crossover effect occurs during canine BAER testing, but that use of white masking noise in the non-test ear of 20 decibels below click stimulus intensity is sufficient to abolish this effect. In particular, I demonstrate the importance of the crossover effect in asymmetrical hearing loss, where it may cause false positive results if white noise masking in the non-test ear is not used. However, while optimisation of the BAER is important, the availability of congenital sensorineural deafness screening in dogs is still limited by the cost and complexity of the BAER equipment. Otoacoustic emission (OAE) testing has largely replaced BAER testing in human neonatal audiological screening and only neonates failing OAE testing are usually referred for BAER testing. OAE testing is considered quicker and less invasive and can easily be automated, so it has potential as a first-pass screening modality in veterinary practices but has never been assessed in the clinical veterinary setting. In Chapter 4, I show that valid TEOAE and DPOAE responses can successfully be recorded in dogs within the clinical veterinary setting and OAE testing correctly identifies deaf and hearing ears, as determined by BAER.

Item Type: Thesis (MVM(R))
Qualification Level: Masters
Additional Information: Due to copyright restrictions the full text of this thesis cannot be made available online. Access to the printed version is available.
Keywords: BAER, DPOAE, TEOAE, dog, hearing
Subjects: S Agriculture > SF Animal culture > SF600 Veterinary Medicine
Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Supervisor's Name: Penderis, Dr. Jacques and Anderson, Dr. T.J.
Date of Award: 2012
Depositing User: Mrs Ana Rita G P Goncalves
Unique ID: glathesis:2012-3679
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Oct 2012
Last Modified: 10 Dec 2012 14:09
URI: http://theses.gla.ac.uk/id/eprint/3679

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