Degenerative Myelopathy (Common Variant)

Other Names: Canine degenerative myelopathy, DM
Affected Genes: SOD1
Inheritance: Autosomal Recessive With Incomplete Penetrance
Mutation: chr31:26540342 (canFam3): G>A
Breed(s): Airedale Terrier, Alaskan Malamute, American Bulldog, American Bully, American English Coonhound, American Eskimo Dog, American Foxhound, American Hairless Terrier, American Pit Bull Terrier, American Staffordshire Terrier, American Water Spaniel, Anatolian Shepherd Dog, Aussiedoodle, Australian Cattle Dog, Australian Cobberdog, Australian Kelpie, Australian Koolie, Australian Labradoodle, Australian Shepherd, Australian Stumpy Tail Cattle Dog, Australian Terrier, Australian Working Kelpie, Beagle, Belgian Malinois, Belgian Sheepdog, Belgian Shepherd, Belgian Tervuren, Bernedoodle*, Bernese Mountain Dog, Bichon Frise, Biewer, Black and Tan Coonhound, Bloodhound, Bluetick Coonhound, Bohemian Wirehaired Pointing Griffon, Border Collie, Border Terrier, Bordoodle, Borzoi, Boston Terrier, Boxer, Boykin Spaniel, Bulldog, Bullmastiff, Canaan Dog, Cardigan Welsh Corgi, Carlin Pinscher, Carolina Dog, Catahoula Leopard Dog, Cavalier King Charles Spaniel, Cavapoo, Cavapoochon, Cesky Fousek, Chesapeake Bay Retriever, Chihuahua, Chinese Crested, Chow Chow, Clumber Spaniel, Cockapoo, Cocker Spaniel, Collie, Coton de Tulear, Czechoslovakian Wolfdog, Dalmatian, Danoodle, Decker Terrier, Deutsch Kurzhaar, Deutsch-Drahthaar, Doberman Pinscher, Dogo Argentino, Dutch Shepherd, English Cocker Spaniel, English Coonhound, English Shepherd, English Springer Spaniel, English Toy Spaniel, Finnish Lapphund, Finnish Spitz, Flat Coated Retriever, Fox Terrier, French Bulldog, German Pinscher, German Shepherd Dog, German Shorthaired Pointer, German Wirehaired Pointer, Giant Schnauzer, Golden Retriever, Goldendoodle, Gordon Setter, Great Pyrenees, Greyhound, Groenendael, Harrier, Hovawart, Irish Red and White Setter, Irish Setter, Irish Terrier, Irish Wolfhound, Irishdoodle, Jack Russell Terrier, Keeshond, Kerry Blue Terrier, King Shepherd, Komondor, Koolie, Kuvasz, Lab/Golden Cross, Labradoodle, Labrador Retriever, Laekenois, Lancashire Heeler, Landseer Newfoundland, Lapponian Herder, Lucas Terrier, Maltipoo, Maremma Sheepdog, Mastiff, Miniature American Shepherd, Miniature Australian Cattle Dog, Miniature Australian Shepherd, Miniature Fox Terrier, Miniature Poodle, Miniature Schnauzer, Mountain Cur, Newfoundland, Newfypoo*, Norfolk Terrier, Norwich Terrier, Nova Scotia Duck Tolling Retriever, Old English Sheepdog, Old-Time Scotch Collie, Olde English Bulldogge, Parson Russell Terrier, Patterdale Terrier, Pembroke Welsh Corgi, Peruvian Inca Orchid, Pharaoh Hound, Plott, Pointer, Pomeranian, Pomsky, Poodle, Portuguese Podengo, Portuguese Podengo Pequeno, Pug, Puli, Pumi, Rat Terrier, Redbone Coonhound, Redtick Coonhound, Rhodesian Ridgeback, Rottweiler, Rough Collie, Russell Terrier, Russian Wolfhound, Saarloos Wolfdog, Saint Bernard, Saluki, Samoyed, Schnoodle, Scottish Collie, Sealyham Terrier, Service/Assistance Golden Retriever, Service/Assistance Lab/Golden Retriever cross, Service/Assistance Labrador Retriever, Sheepadoodle, Shetland Sheepdog, Shih Tzu, Shiloh Shepherd, Shorty Bull*, Siberian Husky, Siberian Laika, Silken Windhound, Silky Terrier, Smooth Collie, Smooth Fox Terrier, Soft Coated Wheaten Terrier, St. Bernard, Stabyhoun, Staffordshire Bull Terrier, Standard Poodle, Standard Schnauzer, Swedish Lapphund, Tamaskan, Teddy Roosevelt Terrier, Tenterfield Terrier, Tibetan Terrier, Toy Australian Shepherd, Toy Fox Terrier, Toy Poodle, Treeing Walker Coonhound, UK Breed Council Labrador Retriever, Wachtelhund, Welsh Terrier, Whippet, White Shepherd Dog, Wire Fox Terrier, Wirehaired Pointing Griffon, Yorkiepoo, Yorkshire Terrier
*Disease found in parent breed(s)

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Common Symptoms

Degenerative myelopathy caused by Mutation of the SOD1 gene is an inherited neurologic disorder of dogs. This mutation is found in many breeds of dog, though it is not clear whether all dogs carrying two copies of the mutation will develop the disease. The variable presentation between breeds suggests that there are environmental or other genetic factors responsible for modifying disease expression. The average age of onset for dogs with degenerative myelopathy is approximately nine years of age. The disease affects the White Matter tissue of the spinal cord and is considered the canine equivalent to amyotrophic lateral sclerosis (Lou Gehrig’s disease) found in humans. Affected dogs usually present in adulthood with gradual muscle Atrophy and loss of coordination typically beginning in the hind limbs due to degeneration of the nerves. The condition is not typically painful for the dog, but will progress until the dog is no longer able to walk. The gait of dogs affected with degenerative myelopathy can be difficult to distinguish from the gait of dogs with hip dysplasia, arthritis of other joints of the hind limbs, or intervertebral disc disease. Late in the progression of disease, dogs may lose fecal and urinary continence and the forelimbs may be affected. Affected dogs may fully lose the ability to walk 6 months to 2 years after the onset of symptoms. Affected medium to large breed dogs can be difficult to manage and owners often elect euthanasia when their dog can no longer support weight in the hind limbs. Affected small breed dogs often progress more slowly than affected large breed dogs and owners may postpone euthanasia until the dog is paraplegic.

Testing Tips

Genetic testing of the SOD1 gene will reliably determine whether a dog is a genetic Carrier of degenerative myelopathy. Degenerative myelopathy is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the SOD1 gene mutation. Reliable genetic testing is important for determining breeding practices. Because symptoms may not appear until adulthood and some at-risk/affected dogs do not develop the disease, genetic testing should be performed before breeding. Until the exact modifying environmental or genetic factor is determined, genetic testing remains the only reliable way to detect neurological disease associated with this mutation prior to death. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Dogs that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.

References

  • Awano T, Johnson GS, Wade CM, Katz ML, Johnson GC, Taylor JF, Perloski M, Biagi T, Baranowska I, Long S, March PA, Olby NJ, Shelton GD, Khan S, O'Brien DP, Lindblad-Toh K, Coates JR. Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy that resembles amyotrophic lateral sclerosis. Proc Natl Acad Sci U S A. 2009 Feb 24; 106(8):2794-9. [PubMed: 19188595]
  • Coates JR, March PA, Oglesbee M, Ruaux CG, Olby NJ, Berghaus RD, O'Brien DP, Keating JH, Johnson GS, Williams DA. Clinical characterization of a familial degenerative myelopathy in Pembroke Welsh Corgi dogs. J Vet Intern Med. 2007 Nov-Dec; 21(6):1323-31. [PubMed: 18196743]
  • Coates JR, Wininger FA. Canine degenerative myelopathy. Vet Clin North Am Small Anim Pract. 2010 Sep; 40(5):929-50. [PubMed: 20732599]
  • Miller AD, Barber R, Porter BF, Peters RM, Kent M, Platt SR, Schatzberg SJ. Degenerative myelopathy in two Boxer dogs. Vet Pathol. 2009 Jul; 46(4):684-7. [PubMed: 19276068]
  • Shaffer LG, Ramirez CJ, Sundin K, Carl C, Ballif BC (2015) Genetic screening and mutation identification in a rare canine breed, the Drentsche patrijshond. Vet Rec Case Rep. 3:e000185.
  • Shaffer LG, Ramirez CJ, Sundin K, Connell LB, Ballif BC (2016) Genetic screening and mutation identification in a rare canine breed, the Cesky fousek. Vet Rec Case Rep. 4:e000346.
  • Shelton GD, Johnson GC, O’Brien DP, Katz ML, Pesayco JP, Chang BJ, Mizisin AP, Coates JR. Degenerative myelopathy associated with a missense mutation in the superoxide dismutase 1 (SOD1) gene progresses to peripheral neuropathy in Pembroke Welsh Corgis and Boxers. J Neurol Sci. 2012 Jul 15;318(1-2):55-64. [PubMed: 22542607]
  • Zeng R, Coates JR, Johnson GC, Hansen L, Awano T, Kolicheski A, Ivansson E, Perloski M, Lindblad-Toh K, O'Brien DP, Guo J, Katz ML, Johnson GS. Breed Distribution of SOD1 Alleles Previously Associated with Canine Degenerative Myelopathy. J Vet Intern Med. 2014 Feb 13. doi: 10.1111/jvim.12317. [PubMed: 24524809]