Page 2073 - Cote clinical veterinary advisor dogs and cats 4th

Vestibular Disease 1037

• If CHF present, use angiotensin-converting PROGNOSIS & OUTCOME Murmurs due to SAS may radiate promi-
enzyme (ACE) inhibitors, furosemide, • Excellent prognosis for small, isolated VSD nently to the right side in some cases; HCM
VetBooks.ir R→L VSD: • Guarded prognosis for large VSD; risk of • Most VSDs are relatively small, with a loud Diseases and Disorders
± pimobendan (p. 408)
is another common differential in cats.
• Surgical repair contraindicated
CHF and/or PH
murmur (grade IV/VI murmur or greater),
• Phlebotomy is used to palliate signs and
maintain packed cell volume (PCV) of • Concurrent substantial AI carries guarded well tolerated, and do not require therapy.
prognosis
55%-65%. Hydroxyurea may be added if • Guarded to poor prognosis for R→L shunts; Prevention
phlebotomy alone is insufficient. severe exercise limitations Genetic basis is possible but unproven in
• Sildenafil 1-2 mg/kg PO q 8-12h indicated most breeds. Consider discouraging breeding
if PH present PEARLS & CONSIDERATIONS of affected animals.
Possible Complications Comments Technician Tips
• Left-sided CHF • In L→R VSD, the RV and pulmonary arte- With isolated L→R VSD, the intensity of
• PH rial circulation act as conduits for VSD flow. the murmur varies inversely with the size
• Shunt reversal (R→L) over time (Eisen- The LA and LV, however, receive increased of the defect (the smaller the defect, the
menger’s physiology); rare venous return, resulting in increased diastolic louder the murmur).
• Mural or valvular endocarditis: rare pressures. Effective forward flow into the
systemic circulation is reduced as a result of SUGGESTED READING
Recommended Monitoring shunt flow. The latter two points account for Beijerink BA, et al: Congenital heart disease. In
• After diagnosis in puppies/kittens with no the increased LV workload and predominant Ettinger SJ, et al, editors: Textbook of veterinary
clinical signs, exam at 6 months, 1 year, and occurrence of left heart failure, not right internal medicine, ed 8, St. Louis, 2017, Elsevier,
then yearly thereafter heart failure, in L→R VSD. pp 1207-1248.
• Frequent monitoring for animals with clinical • VSD and TVD are the two main differential AUTHOR: M. Lynne O’Sullivan, DVM, DVSc, DACVIM
signs and requiring treatment diagnoses for a systolic murmur heard best EDITOR: Meg M. Sleeper, VMD, DACVIM
on the right hemithorax in dogs or cats.

Vestibular Disease Client Education
Sheet

BASIC INFORMATION • Acute-onset vestibular disorders can produce or CVD. The fast phase of the nystagmus
such profound disequilibrium and ataxia that is usually away from the side of the lesion.
Definition some owners believe their animal “had a Change in direction of the fast phase with
Category of disorders that affects the central or stroke.” altered head positions suggests CVD.
peripheral vestibular system of dogs and cats. • Cranial nerve deficits: cranial nerve VII (facial
They usually cause clinical signs of head tilt, PHYSICAL EXAM FINDINGS nerve) paresis is sometimes seen in animals
nystagmus, and/or loss of balance. • Head tilt, nystagmus, and vestibular ataxia with PVD due to its proximity to peripheral
(can cause recumbency and whole-body vestibular structures. Cranial nerves V, VI,
Epidemiology rolling) are hallmarks of PVD and CVD. IX, and XII ipsilateral to lesion may be
SPECIES, AGE, SEX • The most important aspect in localization affected in animals with CVD but not PVD.
• Occurs in dogs and cats of a lesion to the central vestibular system is • Horner’s syndrome: possible with PVD but
• Idiopathic peripheral vestibular disease occurs identification of neurologic signs that cannot rare with CVD; ipsilateral to lesion
in older dogs (usually > 8 years old) but in be attributed to PVD. • Postural reaction deficits are commonly seen
cats of any age. • Mental status with CVD, but should not be observed with
○ Central: often altered (depression, stupor, PVD.
ASSOCIATED DISORDERS or coma) • Paradoxical CVD: lesion location as suggested
Nausea, vomiting ○ Peripheral: animal should be alert by clinical signs related to the head (e.g., head
and responsive but can often appear tilt, nystagmus) does not match the lesion
Clinical Presentation disoriented. location suggested by the postural reaction
DISEASE FORMS/SUBTYPES • Gait: vestibular ataxia (falling, veering, deficits; the latter indicate the true side of the
• Peripheral vestibular disease (PVD): vestibu- leaning, rolling, circling), usually toward the lesion (same side as hopping/proprioceptive
locochlear nerve lesion or inner ear disease side of the lesion; seen with CVD and PVD. deficit).
• Central vestibular disease (CVD): brainstem Hypermetria, intention tremors, and truncal • Bilateral PVD: head tilt and nystagmus
lesion (medulla oblongata) sway can be observed if the cerebellum is may not be present; animals can have wide
affected (CVD). side-to-side head excursions and walk with
HISTORY, CHIEF COMPLAINT • Head tilt: usually toward the side of the a crouched gait.
• Regardless of the underlying cause, most lesion; seen with CVD and PVD • Clinical signs related to disease in other
animals present with a peracute to subacute • Spontaneous nystagmus: occurs with CVD central nervous system (CNS) locations, such
onset of clinical signs. and PVD. Vertical nystagmus occurs only as seizures, behavioral changes, or intention
• The most common chief complaints are head in animals with CVD, and horizontal or tremors, suggest multifocal central neurologic
tilt, nystagmus, and vestibular ataxia. rotary nystagmus can be seen with PVD disease.

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