A Novel Spongiform Leukoencephalomyelopathy in Border Terrier Puppies

Dog 1 was a 3-week-old male Border Terrier puppy referred to the Neurology and Neurosurgery Service of the Veterinary Medical Center, The Ohio State University, for ataxia and tremors. The signs were first noticed 5 days before presentation when the puppy first attempted to walk on its own. The owners reported that the tremors affected mainly the hindquarters. No improvement or worsening of the tremors had been noted over this period. An injectable corticosteroid (unknown type and dose) had been administered 4 days before referral, with no changes in the clinical signs. The tremors were reported to disappear when the puppy was sleeping. There were 3 other puppies from the same litter, which were reported to be normal, as were the parents. On presentation, the puppy showed severe generalized coarse body tremors (with low frequency and high amplitude), most severe in the hindquarters, which showed a characteristic swinging side-to-side or “rocking horse” movement (as illustrated in the supplementary Video S1). The tremors also involved the head and thoracic limbs, but to a lesser degree, and disappeared when the dog was asleep or at rest. Cerebellar ataxia was noted when the dog was trying to walk. The neurological examination was difficult because of the severity of the tremors, but it showed an absent menace bilaterally (considered normal for a 3-week-old puppy), delayed proprioceptive positioning, and hopping that was slightly hypermetric on all limbs. The remaining cranial nerves, spinal reflexes, cutaneous trunci reflex, and vertebral column palpation were unremarkable. Physical examination was within normal limits. Because the characteristics of the tremors, which were coarse and affected mainly the hindquarters, a diffuse or multifocal CNS disorder such as a congenital disorder of myelination was considered the main differential diagnosis. A cerebellar lesion (infectious or inflammatory cerebellar disease, cerebellar hypoplasia, neonatal cerebellar ataxia) also was considered possible, although less likely, based on the type of tremors noted. A complete blood count (CBC) and biochemical profile showed changes considered normal for a puppy. The owners, who also were the breeders, chose humane euthanasia. A complete necropsy was performed. A cerebrospinal fluid (CSF) sample was collected from the cerebellomedullary cistern immediately after euthanasia. The fluid was colorless and clear, with a total protein of 55 mg/ dL (reference range