Progressive abnormal gait in an adult Jack Russell Terrier with a homozygous frameshift variant in <i>SETX</i> (senataxin)

Here we describe an 8-year-old intact male Jack Russell Terrier with a 9-month history of slowly progressive gait disturbances that advanced over 2 years to generalized stiffness without ataxia and severe bilateral hyperflexion of all limbs. Gait evaluation showed high lifting of both pelvic limbs resulting in a hopping movement in the rear end; the right pelvic limb was kept lifted, making the dog trot on the 3 other limbs. Both thoracic limbs were lifted higher than normal. Complete blood count and serum biochemistry analysis including creatine kinase activity were normal. Electrophysiological examination showed no abnormalities. Muscle biopsy samples collected at a later stage of the disease showed no abnormalities. A homozygous frameshift variant in SETX (senataxin) was identified and is predicted to truncate about 85% of the protein. The SETX variant adds a new gene variant to the list affecting Jack Russell Terriers with gait abnormalities.