Vestibular disease

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Characteristic head tilt to affected side in peripheral vestibular disease in an old dog[1]

Vestibular disease is a disease of the vestibular system of older dogs characterized by asymmetric ataxia, head tilt, and pathologic nystagmus.

The vestibular system is the major sensory (special proprioceptive) system that, along with the general proprioceptive and visual systems, maintains balance. Any disease, either peripherally or centrally can cause aberrations in regulation of the vestibular system.

Neuroanatomic localization of observed vestibular signs to either the peripheral or central components of the vestibular system is paramount to the management of the patient with vestibular dysfunction, as the etiology, diagnostic approaches, and prognoses are dependent on the neuroanatomic diagnosis[2].

Causes include:

Otitis externa/interna are the most common cause of vestibular disease, resulting from bacterial infections from inward extension from the auditory canal or via the auditory tube from the pharynx. Less commonly, it may be caused by hematogenous spread of bacteria or foreign bodies such as grass seed migration.

Viruses such as canine herpesvirus appear to play little if any role in the pathogenesis of this condition[12].

This disease is often of acute onset, and dogs may show waxing and waning symptoms prior to disease onset, such as anorexia, vomiting and weight loss. Symptoms are similar regardless of whether the disease primarily involves the peripheral receptors within the semicircular canals (affecting sensory nerves of Cranial Nerve VIII) or centrally within the brainstem (central nuclei, cerebellum or projection pathways).

In clinically affected dogs, the head is usually tilted to the affected side. Concurrent otorrhea, ear pain and pain on opening of the mouth may also be present. Neurological signs such as head tilt, nystagmus, circling and ataxia are characteristic of this disease, and in severe cases, Horner's syndrome and seizures may also be observed.

With lesions of the caudal cerebellar peduncle, the head is tilted contralaterally. An associated ipsilateral hemiparesis may help localize the lesion in these dogs[13]. In dogs with bilateral vestibular disease, nystagmus may be absent.

Otoscopic examination and imaging studies with radiographs, CT and MRI are often normal. CSF analysis may help eliminate central nervous conditions. Surgical biopsy may be required for definitive antemortem diagnosis of structural intracranial diseases.

Specific treatments depend on cause. With peripheral conditions, lateral ear resection or bulla osteotomy may be required to assist drainage when infection is suspected.

With vestibular syndrome (idiopathic), clinical signs usually improve dramatically in 2 - 3 weeks, although the head tilt may persist for longer.

References

  1. Bayfair and Papamoa Vets
  2. Rossmeisl JH (2010) Vestibular disease in dogs and cats. Vet Clin North Am Small Anim Pract 40(1):81-100
  3. Kent M et al (2010) The neurology of balance: function and dysfunction of the vestibular system in dogs and cats. Vet J 185(3):247-258
  4. Gredal H et al (2011) Acute neurological signs as the predominant clinical manifestation in four dogs with Angiostrongylus vasorum infections in Denmark. Acta Vet Scand 53(1):43
  5. Garosi L et al (2010) Necrotizing cerebellitis and cerebellar atrophy caused by Neospora caninum infection: magnetic resonance imaging and clinicopathologic findings in seven dogs. J Vet Intern Med 24(3):571-578
  6. Salvadori C et al (2011) Microcystic meningioma of the fourth ventricle in a dog. J Vet Med Sci 73(3):367-370
  7. Plattner BL et al (2012) Gliomatosis cerebri in two dogs. J Am Anim Hosp Assoc 48(5):359-365
  8. Bentley RT & March PA (2011) Recurrent vestibular paroxysms associated with systemic hypertension in a dog. J Am Vet Med Assoc 239(5):652-655
  9. Gonçalves R et al (2011) Clinical and topographic magnetic resonance imaging characteristics of suspected thalamic infarcts in 16 dogs. Vet J 188(1):39-43
  10. Negrin A et al (2009) Presumptive caudal cerebellar artery infarct in a dog: clinical and MRI findings. J Small Anim Pract 50(11):615-618
  11. Schmidt MJ et al (2012) Porencephaly in dogs and cats: magnetic resonance imaging findings and clinical signs. Vet Radiol Ultrasound 53(2):142-149
  12. Parzefall B et al (2011) Naturally-occurring canine herpesvirus-1 infection of the vestibular labyrinth and ganglion of dogs. Vet J 189(1):100-102
  13. Bagley, RS (2009) vestibular disease of dogs and cats. In:Kirk's current veterinary therapy XIV. Saunders Elsevier, St Louis, MO pp:1097