Cystinuria in Dogs: Causes, Risks & Testing Guide

Cystinuria, or CU, is a hereditary kidney disorder in dogs affecting the reabsorption of cystine, an amino acid. Normally, kidneys filter cystine and reabsorb it, preventing it from passing into the urine. In dogs with cystinuria, cystine remains in the urine where it can crystallise and form stones that may block the urinary tract, especially in male dogs with narrower urethras.

These blockages raise the risk of urinary tract infections and may cause severe complications, including kidney failure or bladder rupture if untreated. The condition is genetic, non-contagious, and requires informed breeding decisions to reduce its spread.

Understanding Cystinuria and Its Effects

Cystinuria is present from birth but may show symptoms much later, sometimes never causing major problems in affected dogs. However, cystine stones can lead to painful blockages and infections, particularly in males where symptoms tend to be more severe. Managing cystinuria often involves diet and medical interventions to reduce stone formation and balance urine acidity.

Breeds at Increased Risk of Cystinuria

Cystinuria prevalence varies by breed and country. In the UK, the Newfoundland puppies and Landseer are notably at risk. Crossbreed dogs may inherit mutated genes but are less likely to be affected due to gene combinations from both parents. Testing is vital for at-risk breeds to support responsible breeding and reduce incidence.

How Cystinuria Inheritance Works

The condition follows an autosomal recessive inheritance pattern. Dogs are classified as clear, carriers, or affected based on the genes received from their parents. Understanding parents' status helps predict the health of the puppies:

• Two clear dogs produce clear puppies.
• Two affected dogs produce affected puppies.
• Two carriers result in 25% affected, 50% carriers, and 25% clear puppies.
• A clear dog and a carrier produce 50% clear, 50% carriers.
• A clear dog and an affected dog produce all carrier puppies.
• A carrier and an affected dog produce 50% carriers and 50% affected puppies.

Testing Your Dog for Cystinuria

Testing involves submitting a DNA sample, typically a cheek swab or blood sample, to approved laboratories. The Kennel Club manages these tests in the UK and records results for certain breeds like the Newfoundland. Knowledge of your dog’s status is essential for breeding choices and managing the disease.

Managing Cystinuria for a Healthier Life

Management focuses on preventing stone formation and urinary infections. A specialised low-protein diet and maintaining urine pH balance help reduce cystine crystallisation. Medications can support urine acidity control but may be costly over time. Prompt veterinary care is crucial if urinary blockage or infections occur. Responsible breeding remains the most effective preventive strategy.

Conclusion

Cystinuria is a serious but manageable hereditary condition in dogs leading to urinary stones and blockages. Awareness, early testing through DNA screening, and careful breeding practices guided by organisations like The Kennel Club greatly help reduce its incidence and improve affected dogs’ quality of life. If you have or plan to breed at-risk breeds such as the Newfoundland puppies, ensure genetic testing is part of your health plan.