Canis ISSN: 2398-2942

Motor neuron disease (Brittany Spaniel)

Synonym(s): Spinal muscular atrophy in Brittany Spaniel, Hereditary canine spinal muscular atrophy, HCSMA

Contributor(s): Kyle Braund, Laurent Garosi

Introduction

  • Cause: dominantly inherited lower motor neurone disease.
  • Three clinical pictures, accelerated, intermediate and chronic.
  • Homozygotes show the accelerated disease, heterozygotes the intermediate or chronic phenotypes.
  • Signs: begin before the puppy reaches maturity and progress.
  • Progressive weakness with muscle atrophy.
  • Treatment: none.
  • Prognosis: accelerated and intermediate forms progress until the puppy is unable to walk.

Pathogenesis

Etiology

  • Inherited by an autosomal dominant trait.
  • Dogs that are homozygous for the trait develop clinical signs between 6 and 8 weeks of age and rapidly progress (accelerated disease) with death ensuing by 4 to 5 months of age.
  • Heterozygotes for the trait are divided into intermediate and chronic forms phenotypically.

Pathophysiology

  • Premature degeneration of the cell bodies of motor neurones.
  • Impaired slow-axonal transport of cytoskeletal proteins, neurofilament proteins and tubulin → build up of material in axons → axonal swelling.
  • Altered levels of choline acetyltransferase activity.
  • Possible alteration in spinal cord glutamate activity.
  • Premature degeneration and death of neuronal cell populations in the spinal cord and brain stem → interruption of nerve impulses to skeletal muscle → decreased or absent reflexes, muscle tone, and voluntary movement → progressive muscle atrophy (seen as prominent thinness and loss of bodyweight).
  • Although there are some indicators of oxidative stress (changes in vitamin E and serum copper levels), these are more likely to be an effect of the disease than a cause.

Timecourse

  • Accelerated disease has a course of about 2 months.
  • Intermediate disease has a course of 1-2.5 years.
  • Chronic disease has a protracted course of several years.

Diagnosis

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Treatment

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Prevention

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Outcomes

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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, Bouley D M, Pinter M J et al (2001) Canine motor neuron disease: clinicopahtological features and selected indicators of oxidative stress. J Vet Intern Med 15 (2), 112-119 PubMed.
  • Braund K G (1996) Degenerative causes of neuropathies in dogs and cats. Vet Med 91 (8), 722-739 VetMedResource.
  • Sack G H et al (1996) Canine genetic linkage study using heterologous DNA probes. J Hered 87 (1), 15-20 PubMed.
  • Cork L C et al (1990) Hereditary canine spinal muscle atrophy - canine motor neurone disease. Can J Vet Res 54 (1), 77-82 PubMed.
  • Cork L C et al (1982) Pathology of motor neurons in accelerated hereditary canine spinal muscular atrophy. Lab Invest 46 (1), 89-99 PubMed.
  • Lorenz M D et al (1979) Hereditary spinal muscular atrophy in Brittany Spaniels - clinical manifestations. JAVMA 175 (8), 833-839 PubMed.


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