Asking a breeder the right SOD1 questions before you buy a puppy is one of the only concrete steps you can take to reduce your future dog’s risk of degenerative myelopathy — a disease that has no cure and progresses without stopping.

Quick answer: When buying a puppy from a breed at risk for degenerative myelopathy (DM), ask to see the SOD1 genetic test results for both parents — not just a verbal assurance. Responsible breeders test both sire and dam and can show you certificates from an accredited lab. The safest pairing produces N/N (Clear) puppies; a Carrier x Clear pairing is widely considered acceptable for pet homes but requires transparency. Any breeder who won't share test results, claims the test is unnecessary, or doesn't know what SOD1 means should be considered a red flag.

Buying a puppy is an emotional experience. You’re looking at wiggly little bodies, answering questions about your yard, and imagining the next decade. The last thing anyone wants to do in that moment is grill a breeder about a degenerative neurological disease. But this is exactly when the questions matter most — because once you’re home and in love, the window has closed.

This guide gives you the specific questions to ask, explains what the answers actually mean, and walks you through the red flags that should make you pause.

What Is SOD1 Testing and Why Does It Matter?

SOD1 testing identifies whether a dog carries a mutation in the SOD1 gene that is strongly associated with canine degenerative myelopathy. The University of Missouri College of Veterinary Medicine characterized this mutation and developed the original test that is now widely used across the veterinary genetics community.

The mutation is autosomal recessive in the way it’s inherited, meaning a dog generally needs two copies of the mutant allele (called “A”) to be at the highest statistical risk for DM. Dogs with one copy are called Carriers. Dogs with no copies are called Clear. Neither carriers nor clear dogs are known to develop DM through this pathway, though research continues.

What the test does not do: it does not guarantee your dog will or won’t develop DM. Other genetic factors and age-related variables appear to influence whether an At Risk dog actually develops the disease. Think of SOD1 status as a risk modifier, not a crystal ball. For a deeper look at what the test tells you and what it doesn’t, the site has a dedicated article on the SOD1 genetic test for DM.

Which Breeds Should You Be Asking About?

The SOD1 A allele appears at meaningfully high frequency in a number of breeds. Among those most commonly discussed:

  • Pembroke and Cardigan Welsh Corgis: Among the highest documented frequencies of the At Risk genotype
  • German Shepherds: A breed where DM is well established as a cause of rear-end weakness in older dogs
  • Boxers: At Risk allele frequency is significant enough that breed clubs encourage testing
  • Standard Poodles: High enough prevalence that Poodle-mix buyers often ask the same questions — see also DM in Standard and Miniature Poodles
  • Chesapeake Bay Retrievers, Rhodesian Ridgebacks, Siberian Huskies, Wire Fox Terriers: All documented in the literature as at-risk populations

The Orthopedic Foundation for Animals maintains a searchable database of SOD1 test results by breed and individual dog. You can look up a sire or dam by registered name before you ever contact the breeder — which is a useful step.

## What Questions Should You Actually Ask a Breeder?

These questions are worth raising directly, and a responsible breeder should answer all of them without hesitation.

“Have both parents been SOD1 tested?” Both the sire and the dam matter. A Clear mother bred to an untested or At Risk father still produces at-risk puppies. Don’t accept testing on one parent only.

“Can I see the actual test certificates?” Verbal assurances are not enough. Legitimate tests produce printed or digital certificates from an accredited laboratory — the OFA, Paw Print Genetics, Embark’s veterinary panel, or a university-affiliated lab. Ask to see the paperwork.

“What are the results for each parent?” The answer should include the genotype: N/N (Clear), N/A (Carrier), or A/A (At Risk). A breeder who says “they tested clean” but can’t name the genotype may not fully understand what they’re looking at.

“What is the expected genotype distribution of this litter?” If you understand basic genetics, you can work this out yourself — but asking the question reveals whether the breeder can too. A Clear x Clear pairing produces only Clear puppies. A Clear x Carrier pairing produces 50% Clear and 50% Carrier puppies. A Carrier x Carrier pairing produces 25% At Risk, 50% Carrier, and 25% Clear puppies.

“Are the individual puppies being tested?” Some breeders test litters, not just parents. If each puppy in the litter has its own certificate, that’s the gold standard — you’ll know exactly what you’re bringing home.

“Does your breed club recommend SOD1 testing?” This opens a conversation about whether the breeder is engaged with health initiatives in their breed community. Corgi and German Shepherd breed clubs, among others, have formal health testing recommendations that include DM.

Reading a SOD1 Result
  • N/N = Clear — no copies of the mutant allele; not a DM risk through this pathway
  • N/A = Carrier — one copy; lower risk, but can pass the allele to offspring
  • A/A = At Risk — two copies; highest statistical risk for developing DM
  • Results from different labs may use different notation (e.g., “Normal/Normal” vs “Clear/Clear”) but mean the same thing

How to Interpret Results Across Generations

Understanding the parents’ results tells you a lot — but multi-generational context matters more than a single-litter snapshot.

A breeder who has been selecting away from the A allele for several generations will have a breeding program with structurally lower risk, even if an individual dog is a Carrier. Ask: “How long has your program been testing for SOD1, and have you been selecting to reduce At Risk pairings?” A breeder who started testing three years ago and has been thoughtfully tracking results is in a very different position than someone who tested once under pressure from a buyer.

Multi-generational records also help you assess the pedigree as a whole. The OFA database allows you to look up dogs by registered name, so if a breeder gives you the sire’s AKC name, you can check whether prior health tests are on file — including SOD1 status.

Breeder Red Flags on SOD1
  • Refuses to show test certificates or says results are “private”
  • Claims the SOD1 test is unreliable or irrelevant to their breed
  • Can’t name the genotype of the parent dogs (only says “they passed”)
  • Tests the dam but not the sire, or vice versa
  • Bred a known A/A dog to a Carrier without disclosing it to buyers

What If Both Parents Are Carriers?

A Carrier x Carrier pairing is not automatically disqualifying — but it does require honest disclosure. Statistically, one in four puppies from this pairing will be At Risk. If a breeder made this pairing and is selling puppies without individual litter testing, you have no way to know which puppy you’re getting.

The ethical path for a breeder in this situation is to test every puppy in the litter individually so buyers can make an informed choice. If they haven’t done that and won’t, you’re being asked to accept unknown genetic risk without the information to evaluate it.

For a fuller discussion of what breeding a SOD1 carrier actually involves, the site has a companion article: Should You Breed a SOD1 Carrier?

Signs of a Health-Focused Breeder
  • Tests both parents and can show certificates for each
  • Provides individual puppy test results when possible
  • Discusses SOD1 as one part of a broader health testing protocol
  • Can explain what each genotype means in plain language
  • Is registered with a breed club that recommends health testing

What About Mixed-Breed or Doodle Puppies?

If you’re buying a Goldendoodle, Bernedoodle, or another Poodle-cross, the same questions apply — Standard Poodles carry the allele at meaningful frequency, and so do some of the other parent breeds. The breeder should be testing both parents regardless of whether the puppies are purebred. If they’re not, the puppies carry unknown SOD1 risk. The article on DM in Doodle mixes covers this in more detail.

Frequently Asked Questions

What SOD1 result is safest when buying a puppy?

A puppy with two copies of the normal allele — listed as N/N or Clear — carries no known SOD1-related DM risk. Two At Risk copies (A/A or Affected) carries the highest genetic risk, while one copy (N/A or Carrier) falls in between. Breeding practices vary, but N/N x N/N pairings produce only N/N offspring.

Can a breeder refuse to share SOD1 results?

Yes, and some do. Refusal is a red flag — responsible breeders who test have no reason to withhold results. If a breeder says they “don’t believe in the test” or that it “doesn’t really predict anything,” treat that as a sign to keep looking.

Is a Carrier (N/A) puppy safe to buy as a pet?

Carriers are at lower statistical risk than At Risk dogs, but they are not risk-free. The SOD1 A allele is necessary but not sufficient for DM on its own — other genetic and environmental factors are believed to play a role. Many pet owners choose N/A dogs knowingly; just go in with clear expectations.

Which breeds need SOD1 testing most urgently?

German Shepherds, Pembroke and Cardigan Welsh Corgis, Boxers, Chesapeake Bay Retrievers, Rhodesian Ridgebacks, and Standard Poodles are among the breeds with the highest documented SOD1 A allele frequencies. Siberian Huskies, Wire Fox Terriers, and Bernese Mountain Dogs are also on the list.

Finding a breeder who takes genetic health seriously isn’t always easy, and I know the puppy search can feel overwhelming. But asking these questions — even if it feels awkward — is the kind of thing you’ll be glad you did ten years from now when your dog is still running circles in the backyard.

This guide is based on real experience and should be used alongside professional veterinary care. Always consult your veterinarian before starting any new treatment or making changes to your dog’s care plan.