Hemilingual tetany ("hemilingual spasm") in a dog

Hemilingual atrophy, often secondary to lesions (e.g. neoplasia) affecting the hypoglossal nerve ipsilaterally, is the only unilateral tongue muscle-related neurological disorder reported in dogs. Hemilingual spasm is a descriptive term used in the human medical literature that refers to a disorder of involuntary, unilateral contractions in tongue musculature. We report a 5-year-old Border collie with hemilingual tetany ("hemilingual spasm"). Clinical examination revealed a resting unilateral contraction of the tongue on the right side with a resultant curvature of the tongue of variable degree with some intermittent incomplete relaxation. These signs disappeared during premedication and induction phases of anaesthesia (dexmedetomidine, butorphanol and propofol). Electromyography of the tongue muscles revealed fasciculation potentials on the right side of the tongue in association with the depth of sedation. CT and two MRI studies did not reveal abnormalities of the tongue musculature, brain or hypoglossal nerves. Hemilingual tetany was diagnosed. No treatment was initiated.