A hypomyelinating leukodystrophy in German Shepherd dogs

Background Shaking puppy syndrome is commonly attributed to abnormal myelination of the central nervous system. Hypothesis/Objectives To report the long‐term clinical course and the imaging characteristics of hypomyelinating leukodystrophy in German Shepherd dogs. Animals and Methods Three related litters with 11 affected dogs. Results The 11 affected dogs experienced coarse, side‐to‐side tremors of the head and trunk, which interfered with normal goal‐oriented movements and disappeared at rest. Signs were noticed shortly after birth. Nine dogs were euthanized, 3 dogs underwent pathological examination, and 2 littermates were raised by their breeder. Tremors improved gradually until 6 to 7 months of age. Adult dogs walked with severe residual pelvic limb ataxia. One dog developed epilepsy with tonic‐clonic seizures at 15 months of age. Conventional magnetic resonance imaging (MRI) disclosed homogenous hyperintense signal of the entire subcortical white matter in 3 affected 7‐week‐old dogs and a hypointense signal in a presumably unaffected littermate. Subcortical white matter appeared isointense to gray matter at 15 and 27 weeks of age on repeated MRI. Abnormal white matter signal with failure to display normal gray‐white matter contrast persisted into adulthood. Cerebellar arbor vitae was not visible at any time point. Clinical signs, MRI findings, and pathological examinations were indicative of a hypomyelinating leukodystrophy. All parents of the affected litters shared a common ancestor and relatedness of the puppies suggested an autosomal recessive mode of inheritance. Conclusion We describe a novel hypomyelinating leukodystrophy in German Shepherd dogs with a suspected inherited origin.