Canis ISSN: 2398-2942

Hearing tests

Contributor(s): Celia Cox, Luc Poncelet

Introduction

  • Deafness can originate in transmission of sound in the outer and middle ear or from defects in the perception of sounds in the cochlea or nervous system.
  • Perception deafness Deafness: acquired Deafness: hereditary has been recognized in over 60 breeds of dogs and some cats. The Dalmatian Dalmatian , English Setter English Setter , Border Collie Border Collie , Australian Cattle Dog Australian Cattle Dog , Cocker Spaniel English Cocker Spaniel , White Bull Terrier Bull Terrier , and white cats are particularly prone to congenital hearing loss (Strain, 1999).
  • Most perception deafness in animals are of the cochleo-saccular type and are associated with the merle or extreme piebald genes in dogs and dominant white gene in cats. Typically, normal, unilaterally deaf and bilaterally deaf puppies are present in such litters of white or mostly white animals. In this entity, if one ear is affected, it is completely deaf.
  • Some neuron-epithelial types of deafness have also been reported in dogs. Deafness is bilateral and may progress over the first months of life in these entities (Coppens et al, 2001).
  • Some medications and acoustic trauma are other possible causes of acquired deafness.
  • Hearing loss varies from complete to partial and can affect one or both ears. Minor losses are generally undetected, but a major loss in one ear can cause difficulty localizing sound, which can significantly reduce the performance of a working dog.
  • There are two main types of hearing tests in dogs:
    • Behavioral tests (subjective).
    • Brainstem auditory evoked response test (BAER) (objective and superior).
  • Neither test causes any significant discomfort to the patient.

Behavioral test

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The Brainstem Auditory Evoked Response (BAER)

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Test procedure

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Bone conduction BAER test

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Uses of the BAER test

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Bianchi E, Dondi M & Poncelet L (2006) N3 potentials in response to high intensity auditory stimuli in animals with suspected cochleo-saccular deafness. Res Vet Sci 81(2), 265-269 PubMed.
  • Coppens A G et al (2001) An original inner ear neuroepithelial degeneration in a deaf Rottweiler puppy. Hear Res 161(1-2), 65-71 PubMed.
  • Strain G M (1999) Congenital deafness and its recognition. Vet Clin N Am Small Anim Pract 29, 895-907 PubMed.
  • Munro K J & Cox C L (1997) Investigation of hearing impairment in Cavalier King Charles spaniels using auditory brainstem response audiometry. JSAP 38(1), 2-5 PubMed.
  • Shui J N, Munro K J & Cox C L (1997) Normative auditory brainstem response data for hearing threshold and neuro-otological diagnosis in the dog. JSAP 38, 103-107 PubMed.


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