Degenerative Encephalopathy in Nova Scotia Duck Tolling Retrievers Presenting with a Rapid Eye Movement Sleep Behavior Disorder

Background:Neurodegenerative diseases are a heterogeneous group of disorders characterized by loss of neurons and arecommonly associated with a genetic mutation.Hypothesis/Objectives:To characterize the clinical and histopathological features of a novel degenerative neurological dis-ease affecting the brain of young adult Nova Scotia Duck Tolling Retrievers (NSDTRs).Animals:Nine, young adult, related NSDTRs were evaluated for neurological dysfunction and rapid eye movement sleepbehavior disorder.Methods:Case series review.Results:Clinical signs of neurological dysfunction began between 2 months and 5 years of age and were progressive in nat-ure. They were characterized by episodes of marked movements during sleep, increased anxiety, noise phobia, and gait abnor-malities. Magnetic resonance imaging documented symmetrical, progressively increasing, T2-weighted image intensity,predominantly within the caudate nuclei, consistent with necrosis secondary to gray matter degeneration. Abnormalities werenot detected on clinicopathological analysis of blood and cerebrospinal fluid, infectious disease screening or urine metabolitescreening in most cases. Postmortem examination of brain tissue identified symmetrical malacia of the caudate nuclei and axonaldystrophy within the brainstem and spinal cord. Genealogical analysis supports an autosomal recessive mode of inheritance.Conclusions and Clinical Importance:A degenerative encephalopathy was identified in young adult NSDTRs consistentwith a hereditary disease. The prognosis is guarded due to the progressive nature of the disease, which is minimally respon-sive to empirical treatment