Otitis media

• Inflammation of the middle ear.
• Cause: sequel to otitis externa, following iatrogenic damage to tympanum, or in association with neoplasia or inflammatory polyps. Hematogenous spread of infection is a rare cause. Otitis media with effusion in cats associated with auditory tube dysfunction secondary to nasal or respiratory disease
• Signs: aural pain, otorrhea, head shaking, Horner's syndrome, concurrent otitis internal, facial nerve involvement.
• Diagnosis: history, clinical signs, otoscopy, radiography, video-otoscopy, advanced diagnostic imaging (CT)
• Treatment: medical if irreversible change not present, topical flushes and antibiotics, ventral bulla osteotomy if chronic irreversible change.
• Prognosis: often poorly responsive to medical therapy as middle ear divided into large ventral and smaller rostrolateral cavity by a bony septum which can trap infection. Guarded if vestibular signs or neoplasia.
  Print off the owner factsheet on Chronic otitis to give to your client.

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

Co-existing otitis interna

• Ataxia 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).

• Inflammatory polyps Nasopharyngeal polyp more common in younger cats (usually <2 years old).

• 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, often seen in cats with a prevoius history of viral respiratory disease. Most polyps appear to arise from the auditory tube (Eustachian tube).
• Otitis media secondary to otitis externa Otitis externa can occur as a result of neoplasia of the external ear canal and/or para-aural abscessation. Infection triggered by allergic otitis externa can lead to descending bacterial infection.
• 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.

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

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

• Intermittent head shaking.
• Affected ear tilted downwards .
• Aural discharge.
• Facial paralysis Facial nerve neuropathy.
• Horner's syndrome Horner's syndrome .

Radiography

Open mouth, dorsoventral and oblique views of whole skull. Useful when chronic change is present and for nasopharyngeal polyps.

• Diffuse thickening/sclerosis of tympanic bulla wall.
• Loss of normal air shadow in tympanic bulla , due to empyema or soft tissue proliferation .
• Bony destruction and proliferative changes of bulla wall .
• Loss of normal air column in external ear due to filling defect.

Other

• Video-otoscopy:
  • Tympanic membrane may be ruptured.
  • Pars tensa loses normal opaque appearance and becomes reddened.
  • 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. Head of polyp can be seen extending into horizontal canal.

• Computed tomography Computed tomography: head:
  • Presence of soft tissue/bony changes within bulla .
• Exploratory surgery and histopathology:
  • Necessary in non-responsive case or neoplasia.

Microbiology

• Cytology and culture and sensitivity may help if discharge present from middle ear. This can be collected through a ruptured tympanic membrane or by myringotomy Myringotomy.

Causes of head shaking, irritation, painful external ear canal

• Otitis externa Otitis externa.
• Aural hematoma Ear: hematoma drainage.
• Aural foreign body.
• Aural neoplasia.

Vestibular syndrome

• Otitis interna Otitis interna.
• Idiopathic feline vestibular syndrome Vestibular disease.
• Congenital vestibular disease Vestibular disease.
• Ototoxicity.
• Neoplasia involving petrous temporal bone or vestibular nerve.
• Nasopharyngeal polyps Nasopharyngeal polyp.
• Trauma Head: trauma.

• Topical antiseptic flush (EDTA tris) and topical antibiotics and glucocorticoids Therapeutics: glucocorticoids.

• Topical antibiotics 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 should be used with care as cats are sensitive to many topical cleaners including chlorhexidine Chlorhexidine in the middle ear. Topical EDTA tris, aqueous enrofloxacin Enrofloxacin and dexamethasone Dexamethasone may be used off license.

• Systemic broad-spectrum antibiotics can be used but should where possible be based on cytology and culture and sensitivity of otic discharge.
• See also ear therapeutics Therapeutics: ear.
• Ventral bulla osteotomy 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.

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

Treatment

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

Monitoring

• Radiography or CT follow up images if clinical improvement needs confirming.

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

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

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

Refereed papers

• Recent references from PubMed and VetMedResource.
• Deleporte S &  Prelaud P  (2021) Single myringotomy for the treatment of otitis media in cats: a retrospective study.  Vet Dermatol 32,  419- 433.
• Swales N,  Foster A &  Barnard N  (2018) Retrospective study of the presentation, diagnosis and management of 16 cats with otitis media not due to nasopharyngeal polyp.  J Feline Med Surg 20 (12), 1082-1086 PubMed. 
• Detweiler D A,  Johnson L R,  Kass P H &  Wisner E R  (2006)  Computed tomographic evidence of bulla effusion in cats with sinonasal disease: 2001-2004.  J Vet Int Med  20 (5),  1080-1084 PubMed.
• 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) 8 (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 3 (2), 254-269 PubMed.