Canis ISSN: 2398-2942

Motor neuropathy

Synonym(s): Central neuropathy, Spinal muscular atrophy

Contributor(s): Kyle Braund, Laurent Garosi

Introduction

  • Affects motor neurones with their cell bodies in the spinal cord and/or motor nucleus of cranial nerves in the brain-stem.
  • Cause: inherited condition in the Brittany Peripheral neuropathies and the Swedish Lapland dog.
  • Also occurs in the Pointer, the Cairn Terrier, the Rottweiler, the German Shepherd dog, the Griffon Briquet Vendeen dog and giant-breed crosses.
  • Several isolated reports of motor neuron disease in puppies of several other breeds, which are believed to be inherited.
  • Signs: progressive neuropathy in pelvic and thoracic limbs.
  • Diagnosis: signs, EMG and nerve conduction studies, nerve and muscle biopsy. Definitive diagnosis is made postmortem.
  • Treatment: none.
  • Prognosis: guarded or poor.

Pathogenesis

Etiology

  • Inherited by an autosomal dominant trait in Brittany spaniels.
  • Inherited by an autosomal recessive trait in Swedish Lapland dogs and English Pointers.

Pathophysiology

  • Hereditary.
  • Theories on the pathogenesis of motor neuron disease include oxidative damage, excitotoxicity, inflammation, autoimmune diseases, and neurofilament disorder.
  • Known genetic causes include mutations in the genes for the SOD-1 (superoxide dismutase) enzyme, in a protein called SMN protein, and in the androgen receptor.
  • SOD-1 catalyzes the conversion of oxygen-free radicals to hydrogen peroxide and oxygen; as such, it is a protective mechanism against free radical-induced damage.
  • Premature degeneration and death of neuronal cell populations in the spinal cord and/or brain stem → interruption of nerve impulses to the skeletal muscles → decreased or absent skeletal muscle function → weakness or paralysis → progressive muscle atrophy.

Timecourse

  • Depends on entity, but usually between a few weeks and 2-6 months. The 'intermediate' and 'chronic' disease in Brittany spaniels may vary from 2-7 years.

Diagnosis

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Prevention

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Olby N (2004) Motor neuron disease: inherited and acquired. Vet Clin Small Anim 34 (6), 1403-1418 PubMed.
  • Green S L et al (2001) Canine motor neuron disease: clinicopathologic features and selected indicators of oxidative stress. JVIM 15 (2), 112-119 PubMed.
  • Mandara M T, Di Meo A (1998) Lower motor neuron disease in the Griffon Briquet Vendeen dog. Vet Pathol 35 (5), 412-414 PubMed.
  • Zaal M D et al (1997) Progressive neuropathy in two Cairn terrier litter mates. Vet Q 19 (1), 34-36 PubMed.
  • Braund K G (1996) Degenerative causes of neuropathies in dogs and cats. Vet Med 91 (8), 722-739 VetMedResource.
  • Cork L C et al (1990) Hereditary canine spinal muscular atrophy - canine motor neurone disease. Can J Vet Res 54 (1), 77-82 PubMed.
  • Cummings J F et al (1989) Focal spinal muscular atrophy in two german shepherd pups. Acta Neuropathol (Berl) 79 (1), 113-116 PubMed.
  • Shell L G et al (1987) Spinal muscular atrophy in two Rottweiler littermates. JAVMA 190 (7), 878-880 PubMed.


ADDED