Felis ISSN 2398-2950

Deafness: congenital (hereditary)

Contributor(s): Agnes Delauche, Rosanna Marsella

Introduction

  • Hereditary deafness.
  • Rare. Estimated as 1% of white cats affected.
  • Cause: autosomal dominant gene.
  • Associated with coat color (white) and blue irises.
  • Signs: bi- or unilateral deafness.
  • Diagnosis: signs, Brain stem auditory evoked response (BAER).
  • Treatment: none.
  • Prognosis: guarded, although unilaterally deaf animals may appear normal.
    Print off the owner factsheet Living with a deaf cat  Living with a deaf cat to give to your client.

Pathogenesis

Predisposing factors

General

  • Genotype of parents.
  • Genotype of offspring.
  • Breed.

Pathophysiology

  • One gene for color is linked to deafness in cats.
  • Autosomal dominant gene for coat color W (white).
    Note: not the same as albino.
  • Homozygous offspring are white and may have blue eyes and deafness.
  • Are not blind/sterile as in dogs.
  • More cats with two blue eyes are deaf than with one blue eye.
  • The genes for blue eyes and deafness have incomplete dominance.
  • Affects longhair cats more severely.
  • A second gene is for coat color piebald (S). Unlike dogs this does not appear to be connected to deafness.
  • Some white cats have a gene for Siamese dilution pigment. These are blue-eyed but not deaf (may explain why fewer purebred cats are deaf than crossbred).
  • Neonatal kittens   →   absence of melanocytes (function unknown) in stria vascularis of cochlea   →   degeneration of stria vascularis   →   degeneration of hair cells of cochlear ducts   →   sensorineural deafness.

Timecourse

  • Degeneration of inner ear structures completed by 3-4 weeks old.

Diagnosis

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Strain G M (1999) Congenital deafness and its recognition. Vet Clin North Am Small Anim Pract 29 (4), 895-907 PubMed.
  • Strain G M (1996) Aetiology, prevalence and diagnosis of deafness in dogs and cats. Br Vet J 152 (1), 17-36 PubMed.
  • Strain G M (1991) Congenital deafness in dogs and cats. Compend Contin Educ 13 (2), 245-50 VetMedResource.


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