Cystinuria

Cystinuria in Mastiffs

⸻

What is Cystinuria?

 

Cystinuria is a hereditary metabolic condition that affects the way the kidneys process certain amino acids, particularly cystine.

 

In dogs affected by cystinuria, cystine is not properly reabsorbed by the kidneys and instead passes into the urine. Because cystine does not dissolve easily, it can form crystals or stones in the urinary tract.

 

These stones may cause:

 

• Difficulty urinating

• Urinary tract irritation

• Blood in the urine

• Pain or discomfort

• In severe cases, urinary blockage, which is a veterinary emergency

⸻

Cystinuria in Mastiffs

 

In Mastiffs, the form associated with the breed is commonly referred to as Type III cystinuria. Unlike some other inherited conditions, the genetics of this form are not yet fully understood.

 

It is most commonly associated with intact male dogs, although not all dogs with a genetic marker will ever develop stones.

 

Because of this complexity, testing should be viewed as part of a wider health management approach, rather than a simple positive or negative diagnosis.

⸻

DNA Marker Testing

​

A DNA test is available that detects a genetic marker associated with an increased risk of cystine stone formation in Mastiffs.

 

It is important to understand that this test:

 

• Does not diagnose cystinuria

• Does not predict whether a dog will develop stones

• Indicates whether a dog may carry a genetic susceptibility

 

DNA testing can be carried out through several veterinary genetic laboratories.

⸻

Urine Screening

 

Because the DNA test identifies risk rather than the disease itself, urine screening is also recommended, particularly for intact male Mastiffs.

 

The nitroprusside urine test detects cystine in the urine and can help identify dogs that may be developing crystals or stones.

 

Routine screening can help identify problems early before serious complications develop.

⸻

Responsible Monitoring

 

At Womlu Mastiffs, we believe responsible breeding and ownership includes staying informed about breed health and supporting ongoing research.

 

Cystinuria is a complex condition within the Mastiff breed, and testing should always be considered alongside:

 

• Veterinary advice

• Good breeding practices

• Ongoing health monitoring

 

Our goal is always to promote the long-term health, soundness, and temperament that make Mastiffs such wonderful companions