Introduction

• Cause: infection via middle ear or through hematogenous spread.
• Signs: head tilt, circling and nystagmus (vestibular syndrome).
• Deafness and disturbances of balance occur together.
• Facial nerve and sympathetic trunk can be involved in middle ear. Virtually always unilateral.
• Important to differentiate this disorder from central vestibular disturbances.
  Print off the owner factsheet on Chronic otitis to give to your client.

Pathogenesis

Etiology

• Extension of opportunistic infection by Staphylococcusspp Staphylococcus spp ,Streptococcusspp Streptococcus spp, Malassezia,Clostridium welchii and (especially) Pseudomonas aeruginosa Pseudomonas aeruginosa.
• Iatrogenic: trauma due to excessive pressure from overzealous irrigation or use of ototoxic compounds in irrigating middle ear.
• Idiopathic form: hematogenous spread of infectious agent, possibly viral.
• Trauma to head (rare).

Predisposing factors

• Dogs prone to otitis externa, eg German Shepherd Dog German Shepherd Dog , Spaniels English Springer Spaniel , dogs with pendulous or hairy ears, dogs with generalized skin conditions.

Specific

• Otitis media Otitis media.
• Bulla irrigation or bulla osteotomy Bulla osteotomy.

Pathophysiology

• Trigger factor usually unilateral spread of otitis media through round cochlear window to inner ear → in process facial nerve and sympathetic trunk to eye may be damaged → facial paralysis and partial or complete Horner's syndrome on affected side → loss of function of cochlea and semicircular canals → unilateral deafness and disturbance of balance.

• Direct hematogenous infection of inner ear.
• Iatrogenic damage during treatment of otitis media, through overzealous irrigation or use of ototoxic compounds for irrigation.
• Head trauma → damage to round cochlear window → leakage of perilymph from semicircular canals.

Diagnosis

Treatment

Prevention

Outcomes