VSPN AOW : Difficulty walking and tr... |
Difficulty walking and trembling in a 10-year-old female Akita Inu.J Am Vet Med Assoc. June 2023;261(6):926 - 928.
Companion NotesCase report of orthostatic tremors in a dog
Introduction on primary orthostatic tremors (OTs) - benign involuntary movement disorder - usually reported in young giant- or large-breed dogs - between 9 months and 2 years of age - but in retrievers it seems to appear later in life - involves progressive involuntary, high-frequency tremor in hindlimbs - primarily affecting them during the standing position - can progress to most often involve the forelimbs - but also the trunk and head - affected dogs appear reluctant to lie down - they can have difficulty in sitting and standing - tremors can be confused with weakness or exercise intolerance - typically tremors disappear when affected legs are raised from the ground - or during walking, sitting, or lying down - OTs can be divided into primary OT (considered idiopathic) and OT-plus - OT-plus involves OT in dogs with other concomitant neurological disease - diagnosis of primary OTs is based on the following: - typical clinical presentation - positive weight-bearing lifting test - conscious EMG in weight-bearing posture showing high-frequency tremors - “helicopter sign” - sound resembling a distant helicopter during auscultation with stethoscope (over limb with tremors) - in human medicine - regardless of medication, response is often scarce and minimal - clonazepam is the 1st choice - second-line options include the following: - gabapentin - primidone - sodium valproate - carbamazepine - phenobarbital - deep brain stimulation used successfully - in canine medicine - medication options appear to give a higher rate of improvement than humans - gabapentin and phenobarbital used in most recently published reports - improvement is usually partial
Case report of 10-year-old 29.3 kg [64.6 lb] neutered sex:F dog - history of a commercial diet and regular vaccination - at referral for difficulty in walking and trembling in hindlimbs of 6 years' duration - tremors progressed in last 4 months, mildly involving the forelimbs - physical examination: unremarkable - neurological examination - limb tremors, while standing - mostly hindlimbs and very mild in forelimbs - disappeared in lie-down position - difficulty in sitting - positive weight-bearing lifting test - tremors discontinued after lifting and keeping hindlimbs air-floating - neurolocalization - tremors predominantly in limbs - triggered by standing and discontinuing after keeping hindlimbs air-floating - and during lie-down position - suggestive of orthostatic tremors - lesion involving 1 or more of the following suspected: (considering recent literature) - suspect spinal cord lesion involving 1 or more of the following: - ventral gray column - α-motor neurons - spinal cord gray matter interneurons - intracranial structures (brainstem and cerebellum) - likely location of lesion using human medicine concerning orthostatic tremors - central generator, called the “central oscillator,” demonstrated - located predominantly in cerebellum and brainstem - but other areas seem to be involved in this circuit - creating a ponto-cerebello-thalamo-motor cortical activation - differential diagnoses for a 10-year-old dog with chronic standing tremors (and difficulty lying down) - OTs - benign idiopathic rapid postural tremors - these appear in older dogs - not associated with any type of difficulty in lying down - usually do not disappear with a weight-bearing lifting test - tremors due to paresis as a consequence of a neuromuscular disease - causing exercise intolerance and weakness - neuromuscular disease unlikely - since evaluation of spinal reflexes was unremarkable - degenerative lumbosacral stenosis causing cauda equina compression - degenerative lumbosacral stenosis ruled out due to the following: - unremarkable lumbosacral area palpation - unremarkable perineal reflex - unremarkable extension of the lumbosacral joint (also called “lordosis test”) - sciatic nerve malfunction - chronic orthopedic problems such as hip dysplasia - CBC and serum biochemistry results considered not clinically relevant - leukopenia, slight at 4.39 thousands/μL with reference at 5.49-8.23 - high ferritin, mild at 302 ng/mL with reference at 84-247 - hypercholesterolemia at 339 mg/dL with reference at 151-249 - orthopedic examination: unremarkable - conscious surface electromyography (EMG) of affected limb muscles - OTs are characterized by pathognomonic high-frequency tremors - during a standing position - high-frequency rhythmic spontaneous discharges of 20 Hz recorded - in all tested limbs - definitive diagnosis: primary OTs - treatment - trial with gabapentin, 3 mg/kg PO bid started - slowly increased to 5 mg/kg bid - owner reported no improvement after 3 months of therapy - dog started showing drowsiness - owner declined other medical options and gabapentin was stopped - outcome after 1 year followup, clinical signs unchanged
“The overall prognosis in dogs with OTs is considered to be good, as the disease is benign and slowly progressive.”
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VSPN AOW : Difficulty walking and tr... |
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