Cystinuria in Dogs: Causes, Risks & Testing Guide

Cystinuria (CU) is an inherited renal condition in dogs that disrupts the kidneys' ability to reabsorb cystine, an amino acid. Typically, the kidneys filter cystine out and reabsorb it, stopping it from appearing in the urine. However, dogs with cystinuria excrete cystine in their urine, where it can crystallize and form stones. These stones frequently cause urinary tract obstructions, especially in male dogs, who are more vulnerable due to their narrower urethras.

Such blockages increase the risk of urinary tract infections and can result in serious complications if left untreated, including kidney failure or bladder rupture. This disorder is genetic, not contagious, and requires careful consideration when breeding to lessen its transmission.

What Is Cystinuria and How Does It Affect Dogs?

Cystinuria is present at birth but symptoms may appear much later, or sometimes not at all. While some dogs never develop significant issues, cystine stones can cause painful blockages and infections. Males often experience more severe symptoms. Treatment typically involves dietary adjustments and medical care to prevent stone formation and maintain urinary pH balance.

Breeds Prone to Cystinuria in the U.S.

In the United States, cystinuria is notably observed in breeds such as the Newfoundland puppies and Labrador Retrievers, where type I cystinuria is common. Other breeds affected by various forms include English Bulldogs, French Bulldogs, Mastiffs, Dachshunds, Jack Russell Terriers, Basset Hounds, Irish Terriers, and Chihuahuas. Crossbreeds may carry mutated genes but often are less affected due to gene variation from both parents. Testing high-risk breeds plays a crucial role in responsible breeding to reduce disease occurrence.

Genetic Transmission of Cystinuria

Cystinuria follows an autosomal recessive inheritance pattern. Dogs are categorized as clear, carriers, or affected depending on the genetic makeup inherited from their parents:

• Breeding two clear dogs results in clear puppies.
• Two affected dogs will have affected puppies.
• Two carrier dogs yield 25% affected, 50% carriers, and 25% clear puppies.
• Breeding a clear dog with a carrier produces 50% clear and 50% carriers.
• A clear dog bred with an affected dog results in all carrier puppies.
• Breeding a carrier with an affected dog gives 50% carriers and 50% affected puppies.

How to Test for Cystinuria

Testing involves submitting a DNA sample, often through a cheek swab or blood test, to approved laboratories. In the U.S., several veterinary genetic testing companies offer these services, aiding breeders and owners in knowing their dog’s genetic status. This information is critical for making informed breeding decisions and managing disease risks.

Managing Cystinuria for Your Dog’s Wellbeing

Management aims to prevent the formation of cystine stones and urinary infections. This includes feeding a specialized, low-protein diet and maintaining an optimal urine pH. Certain medications can help control urine acidity but may require ongoing costs. Increasing water intake is vital to dilute urine and reduce stone formation. If any urinary blockage or infection signs appear, prompt care from a veterinarian is essential. Ultimately, responsible breeding remains the best preventive measure.

Summary

Cystinuria is a serious but controllable inherited condition causing urinary stones and blockages in dogs. Raising awareness, early DNA testing, and selective breeding via reputable breeders and veterinary genetic testing services in the U.S. greatly help reduce its incidence and improve quality of life for affected dogs. If you own or plan to breed at-risk breeds such as Newfoundland puppies, integrating genetic screening into your health plan is strongly advised.