Four Interesting Topics for the
Veterinary Practitioner
Otitis externa, Otitis media, Craniomandibular Osteopathy
and Equine Wobblers Syndrome
By : Anabel Holt, AVC 2011
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Otitis Externa
Acute or chronic inflammation of the external ear canal more commonly seen in dogs than cats
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Common causes include parasites, hypersensitivity reactions, foreign bodies, obstructions, and
autoimmune diseases
Perpetuating factors include, but are not limited to, bacterial overgrowth/ infections, yeast
overgrowth/ infections, canal hypertrophy, cerumen gland hyperplasia and adenitis
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Pre-disposing Factors
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Otitis externa is more commonly seen in humid environments, and in the summer months associated
with atopy.
Idiopathic Glandular Hyperplasia of Cocker Spaniels, Springer Spaniels, excessive hair in the ear
canals (Cocker Spaniels and Poodles), pendulous pinnae , and stenotic ear canals (ex: Shar Peis).
Dogs that swim a lot in the summer months often have a greater risk
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Clinical Signs Associated with
Otitis Externa
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Head shaking, rubbing, scratching, discharge from the external ear canal, aural erythema, alopecia of
the ear pinnae, hyperplasia of the ear canal wall, hearing deficits and possibily generalized skin
disease
Chronic/End Stage Otitis externa: Calcification of auricular cartilage
The Different Types of Aural Discharge and their Causes:
Brown “coffee ground” like discharge: ear mites
Brown or Gay discharge: Malassezia (yeast)
Yellow-white discharge: Ceruminous
Yellow-green discharge: Bacteria
Name this ectoparasite.
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Otodectes cynotis
How do you diagnose Otitis
Externa?
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History, clinical signs, physical exam findings, cytologic examination, +/- bacterial culture and
sensitivity
When should a culture and sensitivity analysis be done on an ear swab?
When ROD shaped bacteria are
present!
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What do you see
radiographically?
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Stenosis with an increase in soft tissue opacity in the external ear canal, and in end stage cases,
mineralization of the canal
The VD view is best
The Atlantic Veterinary College, PEI
Treatment Options
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Topical or Systemic corticosteroids
Antibiotics
- repeat cytology every two weeks to determine if treatment is working and whether changes need to
be made
Antifungal drugs
Ear flushing
Resolution often takes up to 3-4 weeks (for the treatment of mites)
Treatment for chronic otitis externa with end stage obstruction:
Total ear canal ablation
Bullae osteotomy
Otitis Media
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An infection of the middle ear, most commonly as the result of the extension of otitis externa through
a ruptured tympanum
Bacteria (primary agents), yeast, neoplasia and nasopharyngeal polyps are common causes
Other causes may include mites (predispose animal to bacterial infections), trauma, and foreign
bodies
Neoplasia and nasopharyngeal polyps are a common causes of refractory otitis media
What diagnostic procedure should be
done in all chronic/reoccurring otitis
externa cases?
An otoscopic exam!
Clinical Signs
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The patient may have a head tilt towards the affected ear.
The animal may paw at the affected ear.
Often a resting or positional rotary or horizontal nystagmus is present
An ipsilateral ventral strabismus may be seen
Ipsilateral mandibular lymphadenopathy may be present
On otoscopic examination, the tympanic membrane may appear dull, bulging and opaque
Pain may be observed when opening the mouth
Facial nerve damage and Horner’s syndrome may be seen
What does it look like
radiographically?
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The opacity of the tympanic bullae is increased
Thickening of the bullae walls are seen (they should be “egg shell” thin)
Best visualized with obliques or open mouth rostrocaudal views
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Treatment
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2-4 month course of systemic antibiotics to prevent relapse (resolution often takes six or more weeks)
Antifungals
Corticosteroids (anti-inflammatory dosage)
Consider flushing ear (s) under general anesthesia
Recheck in 10-14 days
Vestibular signs (head tilt, nystagmus etc), often improve within 2-6 weeks
Owner should be warned that the head tilt and any facial nerve damage or Horner’s Syndrome may
remain
Surgical treatment (save for unresponsive or relapsing infection)
Bullae osteotomy
- complications may include Horner’s Syndrome, Facial paralysis, Vestibular dysfunction, and
deafness
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Ear ablation through horizontal ear canal
Craniomandibular Osteopathy
(CMO)
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A nonneoplastic, non-inflammatory proliferative disease involving the bones of the head
Usually bilaterally symmetrical
Commonly affected breeds include Scottish Terriers, Cairn Terriers, Boston Terriers and West
Highland Terriers
Commonly affected bones: Mandibular rami, occipital and parietal bones, tympanic bullae,
zygomatic portion of the temporal bone
Affects the musculoskeletal system - particularly the muscles involved with prehension and
mastication
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CMO
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Most likely hereditary basis: autosomal recessive in Westies
Usually affects puppies 4-8 months of age
Mandibular swelling, irregular thickening of mandibular rami/ TMJ region
Temporal and masseter muscle atrophy is common
Difficulty/pain with chewing, self-limiting pyrexia
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What does CMO look like
radiographically?
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Bony proliferation on affected bones (mandibular rami, occipital and parietal bones, tympanic bullae,
zygomatic portion of temporal bone)
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Differential DDX for CMO
• Osteomyelitis
• Traumatic periostitis
• Neoplasia
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Treatment Options
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Primarily palliative
May diminish at skeletal maturity (10-12 months of age)
Often surgical placement of a feeding tube and a high calorie, protein rich gruel diet needed
Do not breed affected animals, or repeat breeding of dam and sire
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Crossing to the Other Side:
Equine Wobblers Syndrome
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Two Main types:
Cervical Vertebral Instability (ages 2 months-2 yrs)
A dynamic stenosis found commonly at C5-C6, C6-C7, that compresses the
spinal cord when the neck is flexed.
Cervical Static Stenosis (5-10 yrs of age)
A narrowing of the vertebral canal , most often at C3-C4, C5-C6, that persists
as the neck is put in different ranges of motion
*Affected horses are often noted as fast growing, and of a large frame
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Clinical Signs
•Slowly progressive ataxia and weakness of the limbs, with the hind limbs more
affected
•Signs may appear acutely or worsen after trauma
•UMN/LMN signs are seen
•Knuckling of the fetlocks, toe dragging, tripod stance, circumduction of hind limbs
when circled tightly, reluctance to back, proprioceptive deficits, weak sway response,
OCD and DJD are often seen in conjunction with these syndromes (vertebrae, articular
facets, multiple joints)
Differential Diagnoses
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Cervical Fractures
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Equine Protozoal Myeloencephalitis
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Equine Degenerative Myeloencephalopathy
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EVH-1
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Intervertebral Disk Protrusion
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Space Occupying Mass
Diagnostics
http://www.equinewobblers.com/Diagnostics/Standing-cervical_radiographs.htm
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Radiographs
Tentative Diagnosis: Narrowing of the cervical canal, DJD of the facet joints,
malalignment of vertebrae (evidence of malalignment include: metaphyseal
and epiphyseal flaring, uneven lengths of the vertebral body and dorsal
lamina, malformation and OCD of the articular facets)
Must be lateral
Can measure stenosis: Measure width of the cranial vertebral orifice and of
the widest portion of the epiphysis of the cranial vertebral body. Divide the
width of the orifice by the width of the body
Normal ratios: C2-C6: greater than 0.56, C7: greater than 0.58
ratios less than this indicate stenosis
Diagnostics continued…
•Myelography- best diagnostic procedure to confirm the diagnosis
•General anesthesia is needed
•Special Skills
•High energy x-ray machine
http://www.equinewobblers.com/Diagnostics/Myelogram.htm
Treatment Options
1. Conservative (stall rest, hand walking, altered diet etc)
2. Surgery: Ventral Cervical Vertebral Stabilization
3. Dorsal decompressive laminectomy (replaced by Ventral
Cervical Vertebral Stabilization).
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Questions?
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References
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Brown, M., Christopher & Joseph J. Bertone (2001). The 5- Minute Veterinary Consult Equine. Lippincott Williams &
Wilkins, PA.
Cote, Etienne (2007). Clinical Veterinary Advisor Dogs and Cats. Mosby Elsevier, Missouri.
Stashak, S. Ted (2002). Adams’ Lameness In Horses (5th ed.). Lippincott Williams & Wilkins, PA.
Tilley P. L. & Francis W.K. Smith Jr. (2007). Blackwell’s Five-Minute Veterinary Consult: Canine & Feline (4th ed).
Blackwell Publishing, Iowa.