Degenerative Myelopathy (DM)

last updated draft 2/2/25

Canine degenerative myelopathy (also known as chronic degenerative radiculomyelopathy) is a progressive disease of the spinal cord in older dogs.

The disease has an gradual onset typically between 7 and 14 years of age. It begins with a loss of coordination (ataxia) in the hind limbs. The disease is chronic and progressive, and resulting in paralysis. This disease results in slowly progressive neurological disease that, although not painful but is irreversible.

Dogs affected with degenerative myelopathy ultimately lose muscle mass from the disuse of their back legs and have difficulty getting up to go outside to urinate and defecate.

Degenerative myelopathy initially affects the back legs and causes muscle weakness and loss, and lack of coordination. These cause a staggering effect that may appear to be arthritis. The dog may drag one or both rear paws when it walks. This dragging can cause the nails of one foot to be worn down. The condition may lead to extensive paralysis of the back legs. As the disease progresses, the animal may display symptoms such as incontinence and has considerable difficulties with both balance and walking. If allowed to progress, the animal will show front limb involvement and extensive muscle atrophy. Eventually cranial nerve or respiratory muscle involvement necessitates euthanasia.

Degenerative Myelopathy has an extreme degree of severity.

Symptoms Progression of the disease is generally slow but highly variable. The animal could be crippled within a few months, or may survive up to three years. Weakness in the hind end Toe nail wear in the hind feet Slow reflexes in the hind feet and legs Trouble getting up Loss of coordination in the hind legs Loss of muscle mass in the hind end

Inheritance is complex, autosomal recessive with incomplete penetrance (not all dogs that are homozygous for known disease associated variants show signs of disease during their lifetimes and the involvement of additional genes is also suggested).

*** Don't Confuse with AON, which is similar to Degenerative Myelopathy but DM causes an earlier and more rapid deterioration.

Reading

Cocker Spaniels are not on the "At Risk" list for DM


A few commercial laboratories make this test available for all breed or part of package deals. 

Mis-information can be worse than no information

The International Partnership for Dogs

International Partnership for Dogs (IPFD) is a non-profit organization of global stakeholders to enhance dog health, well-being, and welfare.
Including breed-specific health testing recommendations by Kennel Clubs, Breed Clubs, Veterinary Organizations etc.

DM
Controversial
 Test With Caution*
IPFD gives this the following Relevance Rating: The test is unknown, there is no evidence (i.e. research) available, and may or may not be meaningful for this breed.
DM Mode of Inheritance
IPFD state "Both clinically rare and of complex inheritance. Test is considered poorly correlated with risk for development of DM, and recommendations are to not use the test for breed-wide breeding strategies. While the SOD 1 variant may be commonly found across many breeds, there are few clinical cases observed and confirmed, and in many cases DM has never been observed in the breeds."

DM Around The World

Informal collection from, OFA database
last updated January 2024

informal data collected from CSDB
Data lasted updated January 2025

% are more important when considering these statistics rather than the numbers recorded above, as some dogs results may have been duplicated in different databases

Bernese Mountain Dog, Boxer, Cardigan Welsh Corgi, Chesapeake Bay Retriever, German Shepherd, Golden Retriever, Great Pyrenees, Kerry Blue Terrier, Pembroke Welsh Corgi, Poodle, Rhodesian Ridgeback, Shetland Sheepdog, Soft Coated Wheaten Terrier, Wire Haired Fox Terrier
Breeds Effected By DM

Research Notes on DM

This is not an appropriate mandatory test, until the disease is identified in cocker spaniels.
If that happens then the gene and mode of inheritance would still need to be identified. discovered is definitively agreed upon.
Including test that are not identified as relevant or specific to cocker spaniels could be dangerous when breeding make assumptions from these results.

Degenerative Myelopathy
Gene: Superoxide dismutase 1 (SOD1) on chromosome 31
Variant Detected: Base Substitution c.118G>A p.Glu40Lys
Mode of Inheritance: Autosomal Recessive with Incomplete Penetrance

Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy that resembles amyotrophic lateral sclerosis (2009)Proc Natl Acad Sci;106(8);2794-2799.

Degenerative Myelopathy Early-Onset Risk Modifier (Pembroke Welsh Corgi Type)
Gene: SP110
Variant Detected: chr25:42439453 (canFam3): C/T
Mode of Inheritance: Autosomal Dominant with Incomplete Penetrance
https://pubmed.ncbi.nlm.nih.gov/27185954/

Degenerative Myelopathy (Bernese Mountain Dog Type) Gene: SOD1_c52
Variant Detected: chr31:None (canFam3): A/T
Mode of Inheritance: Autosomal Recessive with Incomplete Penetrance 

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]

Canine degenerative myelopathy. Vet Clin North Am Small Anim Pract. 2010 Sep; 40(5):929-50. [PubMed: 20732599]
Degenerative myelopathy in a SOD1 compound heterozygous Bernese mountain dog. Anim Genet. 2014 Apr;45(2):309-10. [PubMed: 24450472]

Cocker Spaniels are not on the current "At Risk" breed list for this condition.
There is currently generalised all breeds test available in some package deals