Neonatal Cerebellar Ataxia in Coton de Tulear Dogs

Abstract

A neonatal ataxia syndrome was observed in Coton de Tulear dogs. Seven affected pups (32%; 7/22) of both genders came from 5 different litters with phenotypically normal parents. Neurologic examination revealed normal mental status, head titubation, intention tremors, and severe gait, stance, and ocular ataxia beginning at 2 weeks of age. One of the pups was able to walk with assistance, but most of the affected pups were unable to stand and used propulsive movements (“swimming”) for goal‐oriented activities. They frequently would fall to lateral recumbency with subsequent decerebellate posturing and paddling. Ocular motor abnormalities included fine vertical tremors at rest and saccadic dysmetria. The condition was nonprogressive at least until 4 months of age. No specific abnormalities were identified in routine laboratory screening of blood and urine. Cerebrospinal fluid (CSF) analysis was normal in 1 dog, and a mild increase in protein concentration was observed in a second dog. CSF organic and amino acid concentrations were within normal limits. Magnetic resonance imaging and computed tomography of the brain, electromy‐ography, motor nerve conduction studies, and brain stem auditory‐evoked potentials were within normal limits. Postmortem examinations were performed on 5 affected dogs between 2 and 4 months of age. Routine light microscopic and immunocytochemical examination of brain, spinal cord, peripheral nerve, and muscle did not disclose any gross or histologic lesions. Compared with the cerebellum from an age‐matched normal dog, the cerebellum from an affected dog showed synaptic abnormalities, including loss of presynaptic terminals and organelles associated with parallel fiber varicosities within the molecular layer and increased numbers of lamellar bodies in Purkinje cells. An autosomal recessive trait affecting development of the cerebellum is suspected.