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What is Cystinuria?
Cystinuria is an inherited metabolic disorder that can cause stones to form in the kidneys and urinary tract of affected individuals. It has been found in over 60 breeds of dogs including Mastiffs, as well as cats, humans and other animals.
The photo shown above of a cystinuria stone was provided by The “International Kidney Stone Institute”.
Cystinuria in Mastiffs is very complicated and it is extremely important that the Mastiff Community work together to better understand this disease in our breed.  The information that is on this website has been collected from a variety of sources including other websites.  Since the disease is not fully understood in Mastiffs, we are studying the disease in other animals and humans to gather more information. 
If you have a Mastiff with Cystinuria and you have made observations with your dog that may help the researchers or the MCOA Cystinuria Subcommittee Members, please share your information with us and we can learn from one another.
When someone has Cystinuria their kidneys cannot properly reabsorb the amino acids cystine, ornithine, lysine, and arginine (COLA) back into the body and the concentration of these amino acids in the urine increases. Cystine is not very soluble, so elevated levels in the urine can lead to cystine precipitation into crystals. The solubility of cystine decreases as the pH is lowered, so cystine is even less soluble in acidic urine.
As the crystals become larger they can form into cystine stones.  When these crystals and stones pass through the urinary tract it can be extremely painful and when the urinary tract becomes blocked it can be a serious and life threatening problem.
In humans, as well as Newfoundlands & Labrador Retriever dogs with Cystinuria, elevated cystine can be found in both males and females but with Mastiffs the disease seems to affect only the males.  When the male dogs form stones it can be very serious due to their anatomy.

Treating a dog with Cystinuria as one does for other types of urinary stones can make the problem worse, so it is very important that the stones are properly diagnosed by submitting them  to a Stone Analysis Lab to confirm that they are indeed composed of cystine before making changes to the dog’s diet or treating with medications. 


Articles and Information on Cystinuria

MINNESOTA UROLITH CENTER – University of Minnesota
Read more
about Canine Cystine 

University of Pennsylvania Cystinuria Information:
Canine Cystinuria Information:
Cystinuria In Newfoundland Dogs:
Cystinuria Medications
Cats Can Have Cystinuria Too
Human Cystinuria Information:
Human Cystinuria Genetics:
Genetics: Simple to Complex

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