Breed distribution of SOD1 alleles previously associated with canine degenerative myelopathy

J Vet Intern Med. Mar-Apr 2014;28(2):515-21. doi: 10.1111/jvim.12317. Epub 2014 Feb 13.


Background: Previous reports associated 2 mutant SOD1 alleles (SOD1:c.118A and SOD1:c.52T) with degenerative myelopathy in 6 canine breeds. The distribution of these alleles in other breeds has not been reported.

Objective: To describe the distribution of SOD1:c.118A and SOD1:c.52T in 222 breeds.

Animals: DNA from 33,747 dogs was genotyped at SOD1:c.118, SOD1:c.52, or both. Spinal cord sections from 249 of these dogs were examined.

Methods: Retrospective analysis of 35,359 previously determined genotypes at SOD1:c.118G>A or SOD1:c.52A>T and prospective survey to update the clinical status of a subset of dogs from which samples were obtained with a relatively low ascertainment bias.

Results: The SOD1:c.118A allele was found in cross-bred dogs and in 124 different canine breeds whereas the SOD1:c.52T allele was only found in Bernese Mountain Dogs. Most of the dogs with histopathologically confirmed degenerative myelopathy were SOD1:c.118A homozygotes, but 8 dogs with histopathologically confirmed degenerative myelopathy were SOD1:c.118A/G heterozygotes and had no other sequence variants in their SOD1 amino acid coding regions. The updated clinical conditions of dogs from which samples were obtained with a relatively low ascertainment bias suggest that SOD1:c.118A homozygotes are at a much higher risk of developing degenerative myelopathy than are SOD1:c.118A/G heterozygotes.

Conclusions and clinical importance: We conclude that the SOD1:c.118A allele is widespread and common among privately owned dogs whereas the SOD1:c.52T allele is rare and appears to be limited to Bernese Mountain Dogs. We also conclude that breeding to avoid the production of SOD1:c.118A homozygotes is a rational strategy.

Keywords: Amyotrophic lateral sclerosis; Cytoplasmic aggregates; DNA test; Spinal cord.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Dog Diseases / genetics*
  • Dogs / genetics
  • Gene Frequency
  • Genetic Predisposition to Disease / genetics
  • Genotype
  • Homozygote
  • Muscular Atrophy, Spinal / genetics
  • Muscular Atrophy, Spinal / veterinary*
  • Mutation, Missense
  • Species Specificity
  • Superoxide Dismutase / genetics*


  • Superoxide Dismutase