A 4-year-old 6.2-kg (13.6-lb) castrated male terrier-Poodle mixed-breed dog was evaluated because of a 6-month history of bruxism (initially occurring only during stressful events, but progressively worsening), falling, stumbling, bumping into walls and objects, head tremors, pecking motions, behavior changes, urinating and defecating in the house, and not sleeping at night (restlessness and barking). Prior to the referral evaluation, a CBC and serum biochemical profile revealed no abnormalities; an oral cavity examination performed when the dog was sedated did not identify the cause of the bruxism. The dog had been treated with gabapentin (8 mg/kg [3.6 mg/lb], PO, 2 hours before a stressful event), which caused lethargy. Gabapentin administration was discontinued 14 days prior to the referral evaluation. Neurologic examination revealed bright mentation with hyperreactivity to stimuli around the face, absent menace response in the right eye (intermittently absent in the left eye), normal to minimal pupillary light reflexes bilaterally, intermittent right or left head tilt, intention tremors, vestibular and cerebellar ataxia, delayed postural reactions in all 4 limbs, and normal withdrawal reflexes in all 4 limbs.
What is the problem? Where is the lesion? What are the most probable causes of this problem? What is your plan to establish a diagnosis? Please turn the page.
GE LX 1.5-T MR scanner, GE Healthcare, Milwaukee, Wis.
Magnevist (gadopentetate dimeglumine), Bayer HealthCare Pharmaceuticals, Wayne, NJ.
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