Hereditary Calcium Oxalate Urolithiasis, Type 1

English bulldog with yellow ballHereditary Calcium Oxalate Urolithiasis, Type 1 (CaOx1) is an autosomal recessive genetic disorder that greatly increases the risk for formation of CaOx urinary (bladder or kidney) stones.  

Who gets it?

CaOx1 is rare across the dog population as a whole, but it is the most common cause of CaOx urinary stones in English Bulldogs. We have also identified the mutation in the American Staffordshire Terrier, Border Collie, Boston Terrier, Bullmastiff, Havanese, Rottweiler, and Staffordshire Bull Terrier; we believe the mutation is likely present in additional breeds, especially those related to the bulldog lineage. If you are interested in testing a breed not listed here, you are welcome to contact us first at [email protected] to obtain information on the likelihood that the mutation exists in your breed of interest. 

What are the clinical signs?

CaOx stones can form in the kidneys or bladder. This causes irritation that may manifest as straining to urinate, frequent urination, urgency with urination, blood in the urine, or life-threatening urinary obstructions. Dogs affected by hereditary CaOx1 can develop stones as puppies or adults with an average age of 3 years at diagnosis. Recurrence is common. Though many patients have serious consequences, some remain asymptomatic. Males are significantly more likely to form stones than females.   

How is it managed?

Once diagnosed, stones can be treated surgically or with other removal techniques, but the disease tends to recur without additional intervention. Recommendations on preventative measures can be found at the Minnesota Urolith Center:

Boston Terrier

Genetic test results can be used to help guide medical management of affected dogs, identify dogs at risk even before they form stones, and to inform breeding decisions.

We are currently conducting research to determine which therapies are most likely to reduce stone risk specifically for dogs with hereditary CaOx1. If your dog is affected, you can help with this research by submitting a urine sample for special analyses in our laboratory (no charge). Please contact us at[email protected] for more information. We will update this website as we learn more about the best treatment for this disease.   

Other hereditary stone types in bulldogs

Bulldogs are also reported to be at increased risk for two other hereditary urinary stone types: cystine and urate. 
  • Cystine stones in most bulldogs are believed to be androgen-dependent (Type 3 cystinuria). Type 3 cystinuria causes stone risk only in intact male dogs, and urine cystine levels normalize with chemical or surgical castration, eliminating risk for additional cystine stone formation. The precise mutation responsible for Type 3 cystinuria is currently unknown, and we therefore do not offer genetic testing for this condition. More information on cystine stones can be found at Canine Cystine
  • Urate stones in bulldogs are primarily caused by a mutation in the uric acid transporter gene, SLC2A9. This mutation increases uric acid concentrations in the urine (hyperuricosuria, HUU), resulting in risk for urate urinary stones. We offer a genetic test to screen for the HUU mutation. This can be performed alone or as a "combo test" with CaOx1 testing. More information on urate stones can be found at Canine Urate

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Poodle Mix

If you wish to contribute financially to the Canine Genetics Research Fund please donate online.

Scientific References

Saver A, Lulich JP, Van Buren S, Furrow E. Vet Rec. 2021:e141. doi: 10.1002/vetr.141

Contact Us

Canine Genetics Lab
University of Minnesota
1988 Fitch Ave
AS/VM 295
St. Paul, MN 55108
[email protected]

Step 3 - Submit Payment

CaOx1 or HUU

  • 1-3 Dogs - $65 ea.
  • 4 or more - $58 ea.

CaOx1 + HUU "Combo"

  • 1-3 Dogs - $100 ea.
  • 4 or more - $85 ea.

Submit Payment

Need cheek swabs?  Cheek swabs are not included in the purchase price. Links to several purchasing options are available within the cheek swab protocol.

Learn more about the work of the Minnesota Urolith Center, which has received more than one million bladder stones for diagnosis and strives to minimize pain and avoid invasive surgery.