MRI of the inner ear and vestibular system in dogs

Why the neurological exam is not the last word

The first question in a vestibular dog is whether the lesion is peripheral (inner ear or vestibulocochlear nerve) or central (brainstem or cerebellum). How well the neurological examination predicts the MRI result differs between studies, and in both studies below it sometimes mislocalised the lesion.

• In 93 dogs at two German referral clinics (Bongartz et al., Journal of Small Animal Practice), 61 of 62 dogs localised as central by examination had a central lesion on MRI (98.4%). Of 31 localised as peripheral, only 24 (77.4%) had a consistent lesion. The authors recommend imaging dogs with peripheral signs that do not respond rapidly to treatment.
• In 496 dogs that had head MRI (Boudreau et al., Journal of the American Veterinary Medical Association, 2018), 185 had vestibular signs and 151 of these had MRI abnormalities: central in 110 and peripheral in 29. Of 160 dogs classified as central by examination, 98 (61%) had a central lesion on MRI. Interobserver agreement on the examination was good, yet only 7 of 24 dogs with a consensus clinical call of peripheral disease had a peripheral lesion on MRI.

Causes of peripheral vestibular disease

In 188 dogs with peripheral vestibular disease that all had brain MRI (Orlandi et al., BMC Veterinary Research, 2020):

Diagnosis	Dogs
Idiopathic vestibular disease	128
Otitis media and/or interna	49
Hypothyroidism	7
Suspected congenital vestibular disease	2
Neoplasia	1
Cholesteatoma	1

Increasing age was mildly associated with an idiopathic diagnosis rather than otitis. MRI was normal in 85 dogs (45.2%). The commonest abnormality was contrast enhancement of the facial and/or vestibulocochlear nerve (76 dogs, 40.4%).

Look for intracranial spread

In 30 dogs with meningitis or meningoencephalitis spreading from otitis media-interna (Moral et al., Veterinary Sciences, 2025):

• 96% were brachycephalic
• the neurological examination localised the lesion to the central nervous system in only 33%
• MRI did not show intracranial extension in 20% of dogs despite inflammatory CSF

The authors recommend MRI and CSF analysis when otitis media-interna is diagnosed, especially in chronic or recurrent cases and in brachycephalic breeds.

Otitis on MRI is often incidental

In 380 dogs that had head MRI for any neurological sign (Durr et al., Journal of Veterinary Internal Medicine, 2026), 15.7% had otitis of some kind. Otitis was judged the cause of the signs in only 15 dogs (3.9%), all with otitis media and all but one with otitis interna. It was incidental in 45 (11.8%). Of 32 French Bulldogs, 18 (56%) had otitis: 5 causative and 13 incidental.

Inner ear MRI protocol at a glance

Vestibular dogs are imaged with brain MRI, because central lesions and intracranial spread of otitis are part of the question. FLAIR images matter, because a normal inner ear should suppress on FLAIR (Castillo et al., Veterinary Radiology & Ultrasound, 2020), and post-contrast images show cranial nerve enhancement. MRI may not be sensitive for some inner ear structures, and the 188-dog series notes that CT may have helped in some cases.

What the radiologist looks at

• Central or peripheral. Where the lesion is, whatever the examination suggested.
• FLAIR signal in the inner ear. Perilymph is continuous with cerebrospinal fluid (CSF), so a normal inner ear suppresses on fluid-attenuated inversion recovery (FLAIR) images. In 101 dogs with vestibular signs, affected inner ears in dogs with otitis media/interna showed less FLAIR suppression than the unaffected side and than the other groups.
• Idiopathic cases are not always normal. In 80 dogs diagnosed with idiopathic vestibular syndrome (Foth et al., The Veterinary Journal, 2021), inner ear FLAIR signal differed significantly between the affected and unaffected sides, and the side of the change agreed with the direction of the clinical signs in 92.5%. The authors call this preliminary evidence.
• Cranial nerves VII and VIII. Enhancement was common and carried a less favourable outcome.
• The bulla. In the same series, 18 dogs were suspected to have primary secretory otitis media, with T2-hyperintense material in the bulla and no contrast enhancement.
• Cause or bystander. Otitis media alone should not cause vestibular signs, so the reader states whether the inner ear, the nerves and the adjacent brain are involved.

What your report will include

Every Veheri case is read by a radiologist or neurologist, and when you order you can choose Diplomate-only reporting or the full specialist panel. Neurology reporting covers CT and MRI. You can chat directly with the specialist assigned to your case, and a simplified pet owner report helps you explain the findings to the owner.

When you take the report forward:

• Otitis media-interna on MRI: the authors of the 30-dog study recommend MRI and CSF analysis together, because MRI did not show intracranial extension in 20% of dogs despite inflammatory CSF.
• CSF on its own is not enough. In 102 dogs with vestibular disease (Danciu et al., Veterinary Record, 2021), increased CSF cell count had a sensitivity of 49% and specificity of 90% for separating central from peripheral disease, and increased protein 58% and 39%. The authors conclude that CSF analysis is not reliable as the sole diagnostic test.
• Talking to the owner: facial or vestibulocochlear nerve enhancement was associated with a lower chance of resolution, and a history of previous vestibular episodes with a higher chance. Dogs with parenchymal or meningeal involvement from otitis were more likely to keep neurological deficits.

What to include when you request an MRI report

• signalment: age, breed and sex
• onset, duration and progression of signs, and any previous vestibular episodes
• direction of head tilt and nystagmus, mentation, postural reactions and other cranial nerve deficits
• facial paralysis or Horner syndrome
• otoscopic findings and any history of otitis externa
• whether the dog is a brachycephalic breed
• thyroid results and CSF results if available

How Veheri can help

Veheri works with veterinary radiologists and neurologists and reports brain MRI studies remotely for clinics. For the bony middle ear, see CT of the canine middle ear, and for cats, MRI of the feline inner ear.