A breed-related neurodegenerative disease presenting as a sensory ataxic neuropathy has been recognized in a number of related golden retrievers in Sweden. Abnormal movements, especially in the pelvic limbs, were noted in affected animals between 2 and 8 months of age. Common signs were ‘‘bunny hopping'' at high-speed ambulation, unsteadiness, ataxia, avoiding or easily slipping on smooth surfaces and stairs, wearing down pelvic limb claws, male dogs urinating while standing on both pelvic limbs, and carpal hyperextension. No other abnormalities were identified. Movements varied intermittently between hypermetria and hypometria in individual limbs. Proprioceptive placing reactions were abnormal, and spinal reflexes generally were depressed. Patellar reflexes were absent or severely decreased. Overall, pelvic limbs were more severely affected than thoracic limbs. When compared with a group of control dogs, significant differences were found for the ulnar and peroneal nerves. Differences in velocity (but not in amplitude) were compatible with neuropathic disease involving the peripheral portion of the sensory nerves. Histopathologically, the disease is characterized as a subtle degenerative disorder of sensory and motor axons of both the peripheral and central nervous systems (CNS), predominating in CNS sensory afferents. Analyses indicated the disease had a hereditary background. Neither an autosomal recessive inheritance with 1 gene involved nor a polygenic inheritance and environmental factors could be excluded. Ongoing studies may provide information about the clinical nature and the molecular basis of this disease.
COMMENTARY: Pointers, English springer spaniels, long-haired dachshunds, border collies, Jack Russell terriers, and Ibizan hounds are all breeds that have been described as having a form of a sensory neuropathy. Some of these have clinical signs of self-mutilation secondary to involvement of the sensory component of the nervous system. What is interesting is that patients in this study presented with all the clinical signs of degenerative myelopathy (DM); however, their juvenile age earmarks an anomalous disease entity. Golden retrievers are a large breed with a slowly progressive loss of postural response function that affects the hindlimbs more severely than the forelimbs. The dogs in this study had a loss of the patellar reflex, which also occurs in up to 15% of patients with DM. The neuropathy in this study is very difficult to diagnose because even after a sensory nerve conduction velocity study-which is not commonly done even in the university setting-these patients fell in the published normal range until they were compared with age-matched controls of the same breed.
A neurologic syndrome in golden retrievers presenting as a sensory ataxic neuropathy. Jaderlund KH, Orvind E, Johnsson E, et al. J VET INTERN MED 21:1307-1315, 2007.