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Cystinuria Type II-A

Dogs with Cystinuria are not able to reabsorb the amino acid cystine in their kidneys and therefore high concentrations can accumulate in the urinary tract resulting in formation of cystine crystals and stones that can cause obstruction.

Found in

1 in 500 dogs

in our testing

Key Signs

Cystitis, Hematuria, Stranguria, Urinary calculi, Urinary tract obstruction

Age of Onset

1 to 4 yrs

Junior to adult onset


Autosomal Dominant

For autosomal dominant disorders, dogs with one or two copies of the disease variant are at risk of developing the condition. Inheriting two copies of the risk variant may make the risk higher or the condition more severe. They may produce puppies affected with the disorder if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with Cystinuria

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about Cystinuria

Dogs affected by cystinuria present with signs of recurring cystitis, hematuria, stranguria, and pollakiuria. The precipitation of amino acids in the urine results in the formation of crystals and calculi, leading to urolithiasis and urinary tract obstruction, in some cases.

Existing cystine stones should be removed by surgical, mechanical, or medical dissolution methods. Recurrence of cystine uroliths after dissolution or removal is high. The condition can be partly managed through diet therapy and thus dietary options and the importance of diet management should be emphasized to clients.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal dominant meaning that one copy of the mutation is needed for disease signs to occur. Use of dogs with one or two copies of the disease mutation is not recommended, as there is a risk that the resulting litter will contain affected puppies. For example if a dog with one copy of the Cystinuria mutation is bred with a clear dog with no copies of the Cystinuria mutation, about half of the puppies will have one copy and half will have no copies of the Cystinuria mutation. Please note: It is possible that disease signs similar to the ones caused by the Cystinuria mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene SLC3A1
Variant Deletion
Chromosome 10
Coordinate Start 46,725,149
Coordinate End 46,725,154

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Brons, A. K., Henthorn, P. S., Raj, K., Fitzgerald, C. A., Liu, J., Sewell, A. C., & Giger, U. (2013). SLC3A1 and SLC7A9 mutations in autosomal recessive or dominant canine cystinuria: A new classification system. Journal of Veterinary Internal Medicine, 27(6), 1400–1408. View the article