Presumed canine trigemino-abducens synkinesis in a dog.

A ten-year-old male neutered Rhodesian ridgeback cross dog was presented for the investigation of abnormal bilateral protrusion of the third eyelid when chewing. Physical, ophthalmological, and neurological examinations were unremarkable. Thoracic radiographs, abdominal ultrasound, and magnetic resonance of the brain and orbits failed to reveal any abnormalities. Cerebrospinal fluid analysis revealed elevated protein, but the nucleated cell count was normal. trigemino-abducens synkinesis was presumptively diagnosed. Aetiopathogenesis of this condition is discussed. To the authors' knowledge, this is the first report of presumed trigemino-abducens synkinesis in a dog.