Contributors: Agnes Delauche, Rosanna Marsella, Harry Scott

 Species: Feline   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading

Introduction

  • Inflammation of the middle ear.
  • Cause: sequel to otitis externa, following iatrogenic damage to tympanum, or in association with neoplasia or inflammatory polyps.
  • Signs: aural pain, otorrhea, head shaking, Horner's syndrome, concurrent labyrinthitis, facial nerve involvement.
  • Diagnosis: history, clinical signs, otoscopy, radiography.
  • Treatment: systemic antibiosis, bulla osteotomy if indicated.
  • Prognosis: good if uncomplicated bacterial infection responsive to antibiosis, guarded if vestibular signs or neoplasia.
    Print off the owner factsheet on Chronic otitis Chronic otitis to give to your client.Follow the diagnostic tree for Evaluating and Managing Otitis Externa/Media Evaluating and Managing Otitis Externa/Media.

Presenting Signs

  • Head shaking.
  • Head tilt (ipsilateral).
  • Otorrhea.
  • Horner's syndrome Horner's syndrome (ipsilateral).

Co-existing otitis interna

  • Ataxia.
  • Circling (towards the affected side).
  • Loss of balance.
  • Nystagmus (fast phase towards the unaffected side).
  • Deafness Deafness: acquired.
  • Facial nerve paralysis Facial nerve neuropathy (the most common cause of facial paralysis is otitis media/interna).

Age Predisposition

Pathogenesis

Pathophysiology

  • Neoplasia of the external ear or para-aural abscess may lead to secondary otitis media.
  • Occasional sequel to otitis externa Otitis externa, or iatrogenic damage to tympanum during irrigation.
  • Inflammatory polyps Nasopharyngeal polyp commonly cause chronic otitis in the cat but are thought to result from previous episodes of otitis media. Most polyps appear to arise from the auditory tube (Eustachian tube).
  • Otitis media secondary to otitis externa is most likely to occur as a result of neoplasia of the external ear canal and/or para-aural abscessation.
  • The most common cause of chronic otorrhea in the cat is the extension of inflammatory polyps from the middle ear cavity through the tympanum into the horizontal canal.
  • Otitis externa   →   debris accumulation in contact with eardrum   →   eardrum weakened by infection and ruptures   →   medial extension of inflammatory process   →   hyperemia and thickening of mucoperiosteal lining   →   accumulation of exudate in tympanic bulla   →   thickening/sclerosis of bulla   →   medial spread to cause otitis interna or, rarely, bulla osteomyelitis.
  • Iatrogenic damage to tympanum   →   access to middle ear of pathogens   →   inflammatory response   →   otitis interna.

Diagnosis

Presenting Problems

  • Head shaking.
  • Aural pain.
  • Head tilt.
  • Horner's syndrome.
  • Facial paralysis.

Client History

  • Head shaking.
  • Recent upper respiratory tract infection.
  • Aural discharge.
  • Ataxia.
  • Loss of balance.
  • Deafness.
  • Recent irrigation of external ear canal.

Clinical Signs

  • Intermittent head shaking.
  • Affected ear tilted downwards Otitis media: tilted head .
  • Aural discharge.
  • Facial paralysis .
  • Horner's syndrome  Eye: Horners syndrome 01 - affected right eye  Eye: Horners syndrome 01 - normal left eye  Eye: Horners syndrome 02  Eye: Horners syndrome 03  Eye: Horners syndrome 05 - with left facial nerve paralysis .

Diagnostic Investigation

Radiography

Open mouth, dorsoventral  Ear: otitis media and polyp - radiograph DV and oblique  Ear: otitis media and polyp - radiograph VD 10 degree views of whole skull.

  • Diffuse thickening/sclerosis  Ear: otitis media and polyp - radiograph lateral oblique of tympanic bulla wall.
  • Loss of normal air shadow in tympanic bulla  Ear: otitis media (right side) - radiograph VD , due to empyema or soft tissue proliferation  Skull: nasopharyngeal polyp - radiograph lateral pharynx .
  • Bony destruction and proliferative changes  Ear: otitis media and polyp - radiograph VD of bulla wall  Skull: middle ear disease - radiograph DV .
  • Loss of normal air column in external ear due to filling defect.

Other

  • Otoscopy:
    • Tympanic membrane obscured by thin purulent exudate when ruptured.
    • Pars tensa becomes red in color in cases of otitis media.
    • Iatrogenic rupture produces blood in ear canal; perforation can be seen with a surrounding red zone.
    • Inflammatory polyps may be present in external ear or nasopharynx.
  • Computed tomography:
    • Presence of soft tissue/bony changes within bulla  Ear: otitis media (right side) - CT scan .
  • Exploratory surgery and histopathology:
    • Necessary in non-responsive case or neoplasia.

Microbiology

  • Culture and sensitivity may help if discharge present from middle ear.

Differential Diagnosis

Causes of head shaking, irritation, painful external ear canal

Vestibular syndrome

Treatment

Initial Symptomatic Treatment

Standard Treatment

  • Systemic broad-spectrum antibiosis Therapeutics: antimicrobial drug, for at least 3 weeks, based on culture and sensitivity if discharge via ruptured tympanum.
  • See also ear therapeutics Therapeutics: ear.
    Topical treatment, myringotomy and irrigation are not recommended because of sensitivity to ototoxic effects of some disinfectants and antibacterials.
  • Systemic broad-spectrum antibiosis.
  • See also ear therapeutics Therapeutics: ear.
  • Ventral bulla osteotomy (or combined total ear canal ablation Ear: total ear canal ablation and lateral bulla osteotomy if combined otitis media and otitis interna) and irrigation may be necessary if indicated by radiography or medical treatment fails to resolve problem.
    Risk of iatrogenic Horner's syndrome, vestibular disease and facial nerve paralysis, although usually temporary. Care should be taken to avoid damage to round window and the facial nerve.

Monitoring

  • Improvements in clinical signs.
  • Otoscopy: to check external ear and tympanum.
  • Follow up radiography.

Subsequent Management

Treatment

  • Culture and sensitivity if initial antibiotic choice is not effective   →   change according to sensitivity results.

Monitoring

  • Radiography: follow up film if clinical improvement needs confirming.

Outcomes

Prognosis

  • Good if infection or initiating cause can be eliminated. 30% of polyps recur after removal by traction.

Expected Response to Treatment

  • Improvement in demeanor over 24-48 hours.
  • Resolution of head shaking and head tilt.
  • Gradual resolution of any Horner's syndrome.

Reasons for Treatment Failure

  • Neoplasia.
  • Iatrogenic nerve damage due to incompetent surgery.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Allgoewer I, Lucas S & Schmitz S A (2000) Magnetic resonance imaging of the normal and diseased feline middle ear. Vet Rad Ultra 41 (5), 413-418 PubMed.
  • Bruyette D S & Lorenz M D (1993) Otitis externa and otitis media: diagnostic and medical aspects. Semin Vet Med Surg (Small Anim) (1), 3-9 PubMed.
  • Trevor P B & Martin R A (1993) Tympanic bulla osteotomy for treatment of middle-ear disease in cats: 19 cases (1984-1991). JAVMA 202 (1), 123-128 PubMed.
  • Boothe H W (1991) Surgery of the tympanic bulla (otitis media and nasopharyngeal polyps). Probl Vet Med (2), 254-269 PubMed.

Other Sources of Information