Cystinuria

Cystinuria

The development of uroliths (stones) or crystals in the kidneys and/or bladder, often causing irritation and infection in the bladder, painful urination and in some cases, blockage of the urethra.  This has been identified in several other breeds as an inherited genetic defect which prevents the normal reabsorption of cystine, ornithine, lysine, and arginine (referred to as COLA) in the urine which results in the development of crystals and/or uroliths.

  

Symptoms: Frequent urination. Only passing small amounts when urinating at any time.  Chronic bladder infection. Blood in urine.  Urine flow interrupted. Inability to urinate. This is a potentially fatal situation and requires immediate treatment.

Some dogs who may be only very mildly affected or in the earliest stages of this disorder may be asymptomatic and only a urinalysis may identify excess cystine.  Individuals with affected close relatives should have a urinalysis done to determine if this is the case and repeat testing may be necessary.  Testing can potentially offer an early diagnosis and treatment to help avoid more severe symptoms.

Treatment Options:  This can vary depending on the composition of the crystals or stones being formed.  For cystine stones, a low protein diet and a supplement and/or oral prescription may be necessary to adjust the PH in the urine to reduce the incidence of crystal or stone formation.  Treatment should be done with veterinary supervision.

Known Mode of Inheritance: Currently unknown in Cardigans, but some sources list it as X-R, which means it would be mainly passed down on the X chromosome as a recessive.  Males and females can both be affected, but males would be seen more frequently since they only have one X chromosome (XY) and may be more likely to develop a problem due to anatomical differences, while females have two (XX) and would have to inherit it from both an affected sire and a carrier or affected dam to be affected themselves.  There may also be other genetic modifiers and environmental factors, such as diet, which could influence the severity, and age of onset.

Different markers with recessive or dominant inheritance have been identified in other breeds, but none of these have been identified in common with Cardigans.

Age of onset: Symptoms can occur as early as 6 mos, but average age for diagnosis is 3-5 years.

Breeds affected:
  Cardigan: yes
  Pembroke: yes
  Other Breeds: yes

Incidence in Cardigans: Unknown.  Previously considered a rare disorder in the breed, but may be on the increase.

Research/Studies:

  • Cardigans: yes
  • Other breeds: yes
  • Active?: Yes for other breeds, no for Cardigans.

 

Registry: no

Tests Available: yes
A basic urinalysis can by done through any veterinary service for primary diagnosis and evaluation.

There is also ongoing research through UPenn. UPenn Nitroprusside testing information

A urine amino acid quantitation test is the most accurate method for diagnosis, but is also the most expensive and may require specialist referral services since it is primarily a human based diagnostic test.

Breed Specific testing and registry is currently only available for Newfoundlands through OFA. Tests are also available through other testing facilities for Labradors and Mastiffs.
  
Research links:

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