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530 Idiopathic Tremor Syndrome

• Some causes of icterus are infectious or SUGGESTED READING AUTHOR: Laura A. Nafe, DVM, MS, DACVIM
even zoonotic; practice biosecurity mea- Bradbury CA: Jaundice. In Ettinger SJ, et al, editors: EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
sures at least until the cause of icterus is
VetBooks.ir determined. Textbook of veterinary internal medicine, ed 8, St.
Louis, 2017, Elsevier.

Idiopathic Tremor Syndrome Client Education
Sheet

BASIC INFORMATION • Similar characteristics to the human disease • Adjunctive diazepam therapy 0.2 mg/kg PO
called stiff man syndrome, which is due to q 8h can be helpful in decreasing tremors.
Definition an autoimmune reaction against glutamic
• A noninfectious meningoencephalitis primar- acid decarboxylase, an enzyme necessary Chronic Treatment
ily involving the cerebellum that manifests for synthesis of GABA (an inhibitory • After clinical signs are in remission, gluco-
with whole-body tremors and is responsive neurotransmitter). corticoid dose can be slowly decreased over
to immunosuppressive glucocorticoids a 1-3 month period. Decreasing the dose
• Tremor refers to an involuntary, rhythmic, DIAGNOSIS by 25% or less at a time is recommended
oscillatory movement of a body part. to avoid potential recrudescence of clinical
Diagnostic Overview signs.
Synonyms Presumptive diagnosis can be based on signal- • Most patients do not require therapy for
Corticosteroid-responsive tremor syndrome ment, history, and clinical signs. Advanced longer than 3 months. However, some
(CRTS), white dog shaker syndrome, shaker neurodiagnostic workup with MRI and patients may require a long-term low dose,
disease, idiopathic cerebellitis, sporadic acquired cerebrospinal fluid (CSF) analysis can help alternate-day glucocorticoid therapy to
tremors of adult dogs, acquired action-related rule out other causes of tremors. control signs.
myoclonus
Differential Diagnosis Behavior/Exercise
Epidemiology Other types of tremors (p. 1288), toxicities, Until clinical signs resolve, patient should avoid
SPECIES, AGE, SEX infectious encephalitis (cerebellitis, particularly stairs, furniture, and other environments where
• Most common in young (<5 years) and Neospora), congenital abnormalities of myelin a fall could result in injury.
small-breed (<15 kg) dogs formation, or metabolic disorders
• Rare in cats Recommended Monitoring
Initial Database Neurologic exam and clinical signs should
GENETICS, BREED PREDISPOSITION CBC, biochemistry profile, and urinalysis: be monitored as the glucocorticoid dose is
Although white dogs (West Highland white normal tapered.
terrier and Maltese) are overrepresented,
about 50% of cases reported are in dogs with Advanced or Confirmatory Testing PROGNOSIS & OUTCOME
nonwhite coats. • CSF analysis (pp. 1080 and 1323) is most
useful diagnostic test; often shows a mild to Excellent
Clinical Presentation moderate small mononuclear (e.g., lympho-
HISTORY, CHIEF COMPLAINT cytic) pleocytosis with an elevated protein. PEARLS & CONSIDERATIONS
• Acute onset of whole-body tremors, worsen- Occasionally, CSF results are normal or show
ing with stress or excitement albuminocytologic dissociation (normal Comments
• Signs can progress over days to weeks and nucleated cell count with elevated protein). The term white shaker dog syndrome is a
then typically remain static if left untreated. • MRI is most often normal. Changes con- misnomer because about one-half of patients
sistent with mild meningoencephalitis may with idiopathic tremor syndrome do not have
PHYSICAL EXAM FINDINGS be seen. a white haircoat.
• Characteristic finding is a high-frequency, • Histopathology can show a mild nonsup-
low-amplitude, generalized tremor. Tremors purative meningoencephalitis with scattered Technician Tips
are most evident in the head and limbs, often lymphoperivascular cuffs within the CNS, • Hand feeding may be required if the tremors
worsen with excitement and movement, and especially the cerebellum. affect an animal’s ability to properly reach
disappear during sleep. the water and food bowls.
• Additional cerebellovestibular neurologic TREATMENT • Provide a well-padded, lower-level cage and
abnormalities can be seen, including head nonslick surface to prevent falling or injury.
tilt, menace response deficits, nystagmus, Treatment Overview • Keep affected patients in environment with
paresis, ataxia, and ocular tremors. Medical management with immunosuppressive reduced stimuli (e.g., low/dark light and
• Seizure activity has been reported in some doses of glucocorticoids is typically effective at decreased noise) to help decrease tremor
affected dogs. decreasing or eliminating the tremor. Diazepam activity.
• Elevated temperature is possible. can be used as adjunctive therapy. Glucocor-
ticoid dose can be tapered after remission of SUGGESTED READING
Etiology and Pathophysiology clinical signs. Lowrie M, et al: Classification of involuntary
• Inflammatory disease of unknown cause, movements in dogs: tremors and twitches. Vet J
but an immune-mediated cause is strongly Acute General Treatment 214:109-116, 2016.
suspected • Immunosuppressive doses of glucocorticoids
• Tremors are most likely due to a neurotrans- (e.g., prednisone 1-2 mg/kg PO q 12h); AUTHOR: Devon Wallis Hague, DVM, DACVIM
EDITOR: Karen R. Muñana, DVM, MS, DACVIM
mitter imbalance. clinical signs often resolve within a few days
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