Quick Summary
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Phenotype: Affected dogs usually present clinical signs of disease in adulthood (at least 8 years of age) with gradual muscle wasting and loss of coordination typically beginning in the hind limbs. Disease progression continues until the dog is unable to walk. Small breed dogs tend to progress more slowly. In late stages of the disease, dogs may become incontinent and the forelimbs may be affected. Affected dogs may fully lose the ability to walk 6 months to 2 years after the onset of signs.
Mode of Inheritance: Autosomal recessive, incomplete penetrance
Alleles: N = Normal/Unaffected, DM = Degenerative myelopathy
Breeds appropriate for testing: Many breeds carry the SOD1 allele, but the following breeds have been reported as clinically-affected breeds: American Eskimo Dog, Australian Shepherd, Bernese Mountain Dog, Bloodhound, Borzoi, Boxer, Cardigan Welsh Corgi, Cavalier King Charles Spaniel, Chesapeake Bay Retriever, Czech Wolfdog, English Springer Spaniel, German Shepherd, Golden Retriever, Hovawart, Kerry Blue Terrier, Labrador Retriever, Pembroke Welsh Corgi, Pug, Rhodesian Ridgeback, Rough Coated Collie, Soft Coated Wheaten Terrier, Standard Poodle, and Wire Fox Terrier. Crossbred dogs have also been reported as clinically affected by SOD1-associated DM.
Explanation of Results:
- Dogs with N/N genotype will not have degenerative myelopathy and cannot transmit this allele to their offspring.
- Dogs with N/DM genotypes will not have degenerative myelopathy as a result of this allele, but are carriers. They will transmit this allele to 50% of their offspring. Matings between two carriers are predicted to produce 25% of puppies at risk for developing degenerative myelopathy.
- Dogs with DM/DM may have degenerative myelopathy, a disabling condition, and will transmit this allele to all of their offspring.
Results of this test can be submitted to the OFA (Orthopedic Foundation for Animals)
Boxer Health Panel
$80 per animal
Bulldog Health Panel
$105 per animal
Doberman Pinscher Health Panel
$130 per animal
French Bulldog Health Panel 1
$130 per animal
French Bulldog Health Panel 2
$130 per animal
German Shepherd Health Panel
$130 per animal
Golden Retriever Health Panel
$130 per animal
Irish Setter + Irish Red & White Setter Health Panel
$130 per animal
Labrador Retriever Health Panel 1
$165 per animal
Labrador Retriever Health Panel 2
$180 per animal
Nova Scotia Duck Tolling Retriever Health Panel
$140 per animal
Rottweiler Health Panel
$130 per animal
Sample Collection
Dog DNA tests are carried out using cells brushed from your dog's cheeks and gums. The preferred cytology brushes are sent to you by mail, or you may provide your own brushes. For accepted alternative brushes, click here
We recommend waiting until puppies are at least three weeks old before testing.
Step-By-Step:
- Make sure the dog has not had anything to eat or drink for at least 1 hour prior to collecting sample.
- When swabbing puppies, isolate each puppy from the mother, littermates and any shared toys for 1 hour prior to swabbing. Puppies should not have nursed or eaten for 1 hour prior to collecting sample.
- If collecting samples from more than one dog, make sure to sample one dog at a time and wash your hands before swabbing another dog.
- Label brush sleeve with name or ID of dog to be sampled.
- Open brush sleeve by arrow and remove one brush by its handle.
- Place bristle head between the dog’s gums and cheek and press lightly on the outside of the cheek while rubbing or rotating the brush back and forth for 15 seconds.
- Wave the brush in the air for 20 seconds to air dry.
- Insert brush back into sleeve.
- Repeat steps 5 - 8 for each unused brush in sleeve on a fresh area of cheek and gums. Make sure to use and return all brushes sent by the VGL. In most cases, it will be 3 brushes per dog. If using interdental gum brushes, please note that the VGL requires 4 brushes per dog and only moderate or wide interdental gum brushes are accepted.
- Do not seal brushes in sleeve.
- Place all samples in an envelope and return to the address provided.
ATTENTION:
- Do not collect saliva/drool – the key to obtaining a good sample is getting cheek cells on the swab
- Do not rub swab on the dog’s tongue or teeth – this will result in poor quality sample
- Do not collect a sample from a puppy that has recently nursed – the mother’s genetic material can rub off on the puppy’s mouth and contaminate the sample
Degenerative myelopathy (DM) is an inherited neurological disorder of dogs, similar to Lou Gehrig’s disease in humans, that can be fatal. Affected dogs usually begin showing clinical signs of disease in adulthood (at least 8 years of age) with gradual muscle wasting and loss of coordination that typically begins in the hind limbs because of nerve degeneration. Disease progression continues until the dog is unable to walk. Small breed dogs tend to progress more slowly. In late stages of the disease, dogs may become incontinent, and the forelimbs may be affected. Affected dogs may fully lose the ability to walk 6 months to 2 years after the onset of clinical signs. It is important to note that various types of compressive spinal cord disorders can look like early signs of DM.
In clinically-affected breeds, the disease is inherited in an autosomal recessive fashion with incomplete penetrance, and is caused by a allele of the SOD1 gene (c.118G>A). Thus, two copies of the SOD1 allele (reported by the VGL as DM/DM) confer increased risk for DM. However, it is important to understand that not all DM/DM dogs will develop the disease. The variable presentation between breeds and incomplete penetrance supports that DM is not a simply inherited disease but rather has a complex mode of inheritance, meaning that other genetic and environmental factors likely play a role in disease risk and development. There is ongoing research to identify other genetic factors that modify risk for DM in different breeds. A single study has been published to date where Ivansson and colleagues (2016) describe an allele of the P110 nuclear body protein (SP110) gene as a possible modifier of the SOD1 allele in Pembroke Welsh Corgis. Although results showed that DM/DM dogs that also had the SP110 allele were at higher risk than those that were DM/DM only, researchers called for additional studies to further clarify the function of this SP110 allele in disease development.
A 2014 study by Zeng and colleagues revealed the presence of the SOD1 allele (c.118G>A) in crossbred dogs and dogs from 124 breeds. However, breed-specific clinical investigations have not been performed for all breeds that carry this SOD1 allele. The same 2014 study revealed an association between the homozygous DM/DM genotype and histopathology-confirmed clinical DM in mixed breed dogs and dogs from the following breeds: American Eskimo Dog, Australian Shepherd, Bernese Mountain Dog, Bloodhound, Borzoi, Boxer, Cardigan Welsh Corgi, Cavalier King Charles Spaniel, Chesapeake Bay Retriever, Czech Wolfdog, English Springer Spaniel, German Shepherd, Golden Retriever, Hovawart, Kerry Blue Terrier, Labrador Retriever, Pembroke Welsh Corgi, Pug, Rhodesian Ridgeback, Rough Coated Collie, Soft Coated Wheaten Terrier, Standard Poodle, and Wire Fox Terrier.
Genetic testing for the SOD1 allele (c.118G>A), reported by the VGL as DM, helps breeders establish the genetic status of breeding stock and select mating pairs appropriately to reduce the risk of producing DM-affected offspring. Breeding two carriers of the SOD1 allele together is predicted to produce 25% pups that may develop DM.
It is important to note that similar disease presentation has been observed in animals that do not have the SOD1 allele and not all dogs that are DM/DM will develop signs of disease. Testing is most appropriate for those breeds in which the clinical disease has been associated with the SOD1 allele. Despite the high frequency of the SOD1 allele in the canine population, other more common and treatable causes of progressive hind end weaknesses should still be considered even in homozygous DM/DM dogs.