Contributors: Kyle Braund
Species: Canine | Classification: Diseases
Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading
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.
Presenting Signs
- Vestibular syndrome.
- Sudden onset.
- Vomiting
- Concurrent otitis externa Skin: otitis externa +/- otitis media Otitis media.
- General dullness and inappetence.
- Unilateral facial paralysis.
- Rolling and falling towards affected side.
- Hemifacial spasm on affected side.
Breed Predisposition
- Breeds prone to otitis externa, eg Spaniels.
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
General
- 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
Presenting Problems
- Vestibular syndrome.
Client History
- Concurrent long-term otitis externa Skin: otitis externa.
- Concurrent otitis media Otitis media.
- Recent treatment of otitis by instilling potentially ototoxic agents into ear.
- Recent bulla irrigation or bulla osteotomy Bulla osteotomy.
- Head tilt.
- Vomiting.
- Circling.
- Head trauma.
- Seizures.
Clinical Signs
- Head tilt, affected side down.
- Circling towards affected side.
- Nystagmus, fast component away from affected side.
- Stagger towards affected side.
- Unilateral deafness present, but only detectable with sophisticated audiological tests.
- Sudden onset.
- When held up vertically, body hangs straight down.
- Concurrent otitis externa Skin: otitis externa +/- otitis media Otitis media.
- General dullness and inappetence
- Unilateral facial paralysis, involving upper and lower face.
- Rolling and falling in direction of lesion.
- Partial or complete Horner's syndrome: miosis (small pupil), slight ptosis (drooping upper eyelid), enopthalmos (sunken eye), protrusion of third eyelid, conjunctival flare.
- Bilateral otitis interna.
- Hemifacial spasm on affected side.
- Otitis externa Skin: otitis externa.
- Ruptured eardrum.
- Purulent aural discharge.
- Findings if central vestibular involvement:
- Abnormal function of cranial nerve V (trigeminal) - sensory to face; cranial nerve VI (abducens) - eye position → downward strabismus (squint); cranial nerve IX (glossopharyngeal) - gag response; cranial nerve X (vagus) - vocal capacity; cranial nerve XII (hypoglossal) - lingual function.
- Deficits in hopping and placing responses.
- When held up, dog's body turned towards side of lesion.
- Unilateral hypermetria.
- History of recent onset of seizures.
Diagnostic Investigation
Radiography
- To diagnose chronic otitis media Otitis media.
- Absence of normal air shadow in tympanic bulla.
- Diffuse thickening of bulla wall.
- Bony destruction and gross bony proliferative changes in the bulla.
- Gross bony proliferative changes with involvement of the temporomandibular joint.
- Examination under anaesthesia:
- Eardrum rupture identified by palpation with blunt needle or probe Otitis media.
- Eustachian tube not patent Otitis media.
Only test for Eustachian tube patency when a cuffed endotrachial tube is in place.
- Caloric stimulation:
- When otitis interna present, no nystagmus initiated by irrigating external ear canal with warm or cold water.
- Microbiology:
- Bacteriology and sensitivity of aural discharge: mixed infection, including yeasts, susceptible to broad-spectrum antibiotics or polypharmaceutical preparations.
Differential Diagnosis
Peripheral vestibular syndrome
- Canine geriatric vestibular disease Old dog encephalitis.
- Congenital vestibular disease Vestibulocochlear neuritides Patella: medial luxation Patella: lateral luxation.
- Ototoxicity.
- Neoplasia.
- Tumors of cerebello-pontine angle Brain: neoplasia
- Brain stem encephalitis Encephalitis
Treatment
Standard Treatment
- All of: Broad-spectrum, bacteriocidal antibiosis.
- and: Oral corticosteroids.
- and: Bulla osteotomy with bulla irrigation if evidence of otitis media Otitis media.
Monitoring
- Gradual resolution of neurological deficits (balance, circling, nystagmus).
- Resolution of signs of otitis externa Skin: otitis externa /media Otitis media.
Subsequent Management
Monitoring
- Neurological re-examination.
Outcomes
Prognosis
- Reasonable.
Expected Response to Treatment
- Neurological signs resolve over a long time period (months) if effective treatment given.
- Head tilt may be permanent.
Reasons for Treatment Failure
- Caused by neoplasms.
- Standard reasons Standard reasons for failure in a treatment
- Client unable to pay for surgery.
Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Garosi L S et al (2001) Results of magnetic resonance imaging in dogs with vestibular disorders - 85 cases (1996-1999). JAVMA 218 (3), 385-391 PubMed.
- Dvir E et al (2000) Magnetic resonance imaging of otitis media in a dog. Vet Radiol 41 (1), 46-49 PubMed.
Other sources of information
- Rosychuk R A Wet al(2000)diseases of the ear.In:Textbook of Veterinary Internal Medicine.5th edn. Eds: S J Ettinger & E C Feldman. Philadelphia: W B Saunders. pp 986-1002.