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Diseases of the Canine External Ear

The external ear is typically the domain of the Dermatopathologist as it is composed of skin or modified skin. There is considerable overlap between diseases of the external ear and skin. This section will examine those diseases that are unique to the ear of the dog.

Anatomy and Histology

Official terminology of the ear is recorded in Nomina Anatomica Veterinaria and Nomina Anatomica Histologica. The official names are

Auricle for the pinna, and External Acoustic Meatus for the ear canal.

Masses of the Canine External Ear

Epithelial

Ceruminous cysts

Ceruminous adenoma

Ceruminous carcinoma

Lesions without a mass effect

Inflammation

Otitis externa

  1. Predisposing factors
    1. increased moisture
    2. Swimming
    3. reduced ventilation
    4. Excessive hair, conformation
  2. Primary factors
    1. Atopy
    2. Adverse food reactions
    3. Disorders of Keratinisation
    4. Neoplasia
  3. Perpetuating factors
    1. Rupture of tympanic membrane
    2. Otitis media
    3. Acquisition of secondary infections
    4. Progressive proliferative change
      1. Ceruminous gland hyperplasia and ectasia
      2. Stenosis of canal lumen
      3. Alteration to cerumin content.

 

Non-inflammatory lesions

Polypoid hyperplasia