Pseudo-orthostatic tremor in a cat.

An 11-month-old male castrated shorthaired cat was presented with a tremor in both pelvic limbs, which only occurred when standing (ie, countering gravity) or during active extension of the stifle. General clinical and neurological examinations were normal aside from the tremor of the pelvic limbs, which disappeared on performing a weight-bearing lifting test. Needle electromyography of both pelvic limbs in the conscious state confirmed a low-frequency (6 Hz) tremor. The cat was diagnosed with pseudo-orthostatic tremor. The tremor amplitude waxed and waned over time. The cat remained ambulatory and playful, but often assumed lateral recumbency and seemed to have difficulty jumping. Treatment with gabapentin (10-20 mg/kg PO q8h) for 3 weeks followed by clonazepam (0.1 mg/kg PO q12h) for 1 day (with unacceptable adverse effects) did not result in improvement.