Issues

Vestibular Disease, Geriatric—Dogs

 

Vestibular Disease, Geriatric—Dogs is an acute onset non-progressive disturbance of the peripheral vestibular system in older dogs.

 

PATHOPHYSIOLOGY

• Unknown.
• Suspected abnormal flow of the endolymphatic fluid in the semicircular canals of the inner ear secondary to disturbance in production, circulation, or absorption of the fluid.
• Possible intoxication of the vestibular receptors or inflammation of the vestibular portion of the vestibulocochlear nerve (cranial nerve VIII).
• Often incorrectly referred to as a stroke, geriatric vestibular disease is neither central in location nor suspected to be vascular or ischemic in origin.

 

SYSTEMS AFFECTED

Nervous—peripheral vestibular system

 

INCIDENCE/PREVALENCE

Common, sporadic, acquired disease of older dogs

 

SIGNALMENT

Species – Dog

 

Breed Predilections

• None reported
• Seems to occur more frequently in medium to large breeds

 

Mean Age and Range

Geriatric; patients usually > 8 years old

 

SIGNS

General Comments

• Signs of acute onset peripheral vestibular dysfunction usually unilateral but occasionally bilateral.
• If vestibular signs are severe, do not incorrectly attribute the signs (especially the gait) to a central (i.e., CNS) location.

 

Historical Findings

• Sudden onset of imbalance, disorientation, reluctance to stand, and (usually) head tilt and irregular eye movements.
• May be preceded or accompanied by nausea and vomiting.

 

Physical Examination Findings

• Head tilt—mild to marked; directed toward the side of the lesion; occasionally disease is bilateral with erratic side-to-side head movements either without a head tilt or with a mild tilt in direction of the more severely affected side.
• Abnormal (resting) nystagmus common in early stages; either horizontal or rotatory with the fast phase always in the direction opposite to the head tilt; with bilateral disease, abnormal nystagmus usually mild or not present and physiologic nystagmus or conjugate eye movements diminished to absent.
• Mild to marked disorientation and vestibular ataxia with tendency to lean or fall in the direction of the head tilt.
• Strength and proprioception normal; with severe disease, patient may be reluctant to stand and may have other issues (e.g. hip dysplasia), making assessment of gait difficult; with bilateral disease, may have base-wide stance.

 

CAUSES

Unknown

 

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

• Primarily distinguished from other causes of vestibular deficits by the acute onset and usually rapid improvement without specific treatment.
• Otitis media and interna—may have concurrent ipsilateral facial nerve (cranial nerve VII) paresis or paralysis, deafness, and/or Horner’s syndrome; otitis externa with ruptured tympanic membrane may be present with otitis media and interna.
• Ototoxic drugs—eliminated by history.
• Trauma—may cause similar acute changes; differentiated by history, results of physical examination.
• Hypothyroid neuropathy—usually not as acute in onset or as severe; may be associated with clinical signs of hypothyroidism and possible cranial nerve VII deficit.

 

CBC/BIOCHEMISTRY/URINALYSIS

• Generally normal.
• Hemoconcentration secondary to dehydration may be present.
• Unrelated concurrent disorders (e.g., renal and hepatic disease) associated with geriatric state may cause laboratory abnormalities.

IMAGING

• Usually none required.
• Radiographs of tympanic bullae: normal radiographs do not rule out bulla disease.
• CT or MRI (preferred over radiographs)—may be required to rule out other causes such as otitis media and interna.

 

DIAGNOSTIC PROCEDURES

• Brainstem auditory evoked response—to assess cochlear portion of cranial nerve VIII; may help to evaluate for otitis media and interna since only the vestibular portion of cranial nerve VIII is affected with geriatric vestibular disease.
• Deafness may, however, be present as an unrelated aging change.

 

PATHOLOGIC FINDINGS

None reported

 

TREATMENT

APPROPRIATE HEALTH CARE

Mild disease—usually can manage as outpatient.

Severe disease—patients that cannot ambulate or require intravenous fluid support should be hospitalized during the initial stages.

 

NURSING CARE

Treatment supportive, including rehydration by intravenous fluids if required.

Keep recumbent patients warm and dry using soft, absorbent bedding and, if required, urinary catheter.

Severe disease—physical therapy, including passive manipulation of limbs and moving body to alternate sides, may be required initially.

 

ACTIVITY

Restrict activity as required by the degree of disorientation and vestibular ataxia.

 

DIET

No modification usually required.

Nausea, vomiting, and severe disorientation—initially withhold oral intake then supervised feeding.

 

CLIENT EDUCATION

Reassure client that although the initial signs can be alarming and incapacitating, the prognosis for rapid improvement and recovery is excellent.

 

POSSIBLE COMPLICATIONS

Fluid and electrolyte imbalances and decompensation of renal insufficiency (if exists) may follow vomiting and/or insufficient fluid and food intake.

Pressure sores/abrasions.

 

EXPECTED COURSE AND PROGNOSIS

Improvement of clinical signs usually starts within 72 hours with resolution of vomiting and improvement of nystagmus and vestibular ataxia.

Head tilt and ataxia—significant improvement usually occurs over 7–10 days; if no improvement other causes of peripheral vestibular disease should be pursued; mild head tilt may persist.

Most patients return to normal within 2–3 weeks.

Recurrence—repeat episodes of geriatric vestibular disease can occur on the same or opposite side but are uncommon; brief return of signs may occur with stress (e.g., anesthesia).

 

MISCELLANEOUS

AGE-RELATED FACTORS

Geriatric dogs affected (mean age suggested 12.5 years)

 

SYNONYMS

Benign idiopathic canine peripheral vestibular disease

Canine idiopathic vestibular disease/syndrome

Idiopathic canine peripheral vestibular disease

Old dog vestibular syndrome