A litter of five 14-week-old papillon puppies was referred for investigation of pelvic limb ataxia. Clinical examination revealed signs of ataxia, hypermetria and depressed postural reflexes affecting all four limbs. The severity of these signs varied between members of the litter. The condition became progressively worse and by 19 weeks of age all but the least severely affected pup (the single male of the litter) had deteriorated to the point that euthanasia was indicated on humane grounds. Pathological examination revealed widespread changes in both white and grey matter of the neuraxis caudal to the forebrain, particularly involving the dorsolateral white matter of the spinal cord, which were characterised by axonal swellings typical of neuroaxonal dystrophy.