Cystinuria Testing Recommendations

The MCOA Cystinuria Committee recommends screening Mastiffs for Cystinuria between 18 and 24 months of age (or two months before using them for breeding),and repeating the test annually or 2 months before each breeding. 

This is especially important for Mastiffs used in breeding programs.  If your dog is closely related to an affected dog we recommend that you consult with the University of Pennsylvania for special re-testing recommendations and if your Mastiff is affected with Cystinuria we ask that you please participate in the Cystinuria Research Study.

The Cystinuria Nitroprusside test is a simple urine collection which does not require a vet visit but can easily be collected by the owner or breeder preferably 2-4 hours after the dog has eaten. The sample is chilled or frozen and shipped overnight to the PennGen testing lab at UPenn along with a filled out  Cystinuria Urine Submission Form

Should We Test Mastiff Puppies For Cystinuria?

Testing Mastiff puppies younger than 18 months of age (between 6 and 12 months) for Cystinuria is encouraged for UPenn to collect "statistical data on the earliest age of onset". It is very important that the owners go on to re-test at an older age as described above. 

Cystinuria Testing Results

The current Nitroprusside Urine Screening test is very reliable, but Cystinuria in Mastiffs is complex and the cystine levels appear to fluctuate much more than is seen in Newfoundlands. This is most likely due to various metabolic and environmental influences, therefore it is very important to routinely retest dogs that have previously tested negative and dogs that are being used in breeding programs.

It is important to understand the differences between a positive, negative and borderline or equivocal nitroprusside urine test results.  Positive = strong change of color which means there is elevated cystine in the urine which is considered abnormal.  Negative = no change in color or a very slight change in color which is considered normal.  Borderline or equivocal = a change in color that is not strong enough to call it a positive result, yet there is enough change in the color to question whether it is normal or not. 

When the results are borderline or equivocal the results are considered inconclusive and PennGen will ask that the owners to submit another urine sample and to repeat the test.  It the retest shows a positive result then it is considered positive.  If the retest shows a negative result, then the result is negative and considered normal.  When quantitative amino acid tests are ran on the positive nitroprusside urine test samples on Mastiffs, the researchers are also seeing the other elevated amino acids (Ornithine, Lysine and Arginine) in the urine that are consistent with Cystinuria diagnoses.

Cystinuria Urine Screening:

To have your Mastiff screened for Cystinuria using the routine nitroprusside test, please click on this link and print out the Cystinuria Urine Submission Form. 

Please feed your Mastiff 2 to 4 hours prior to collection of urine. Collect at least 3 to 5 milliliter (3-5 cc) urine in a clean urine submission container, for instance a sterile plastic tube with appropriate lids from your local veterinarian.   Make sure you refrigerate the urine and ship it with plenty of frozen cold packs as it must remain chilled.  If you cannot ship the samples right away you can refrigerate them for a few days or freeze them until you are ready to ship them.

Ship the urine samples by overnight delivery on a Monday, Tuesday, or Wednesday in an appropriate insulated container with one or more frozen cold packs. Include a completed urine Cystinuria Urine Submission Form and enclose a check made payable to “Trustees Of The University of Pennsylvania /Dr. Giger” or include your credit card information on the submission form.  The fee is $40 per urine submission.  It is greatly appreciated if you can also include a copy of your dog’s pedigree if it is available and mail everything to:

Dr. Giger (PennGen Testing Lab - Cystinuria Screening
School of Veterinary Medicine - University of Pennsylvania

3900 Delancey Street, Room 4013
Philadelphia, PA 19104-6010
Lab: (215) 898-3375, Office: (215) 898-8894


Do NOT send samples on a Friday or during the Holidays!

Please use FedEx or UPS Overnight Delivery Only

Do NOT use United States Postal Service (USPS)


International Shipping instructions


Please click on this link for International Shipping instructions.

The urine must arrive chilled, so please treat it the same as you would when shipping fresh semen for a breeding. 
Call the lab a head of time to verify that you have the most current address for shipping the sample and to let them know you are shipping it and when it should arrive.
Then track your shipment and call the lab when it shows that it was delivered to verify they received the sample in good condition for testing.  Make sure you enclose enough cold packs and the package is well insulated to keep the sample chilled during shipping.
The results will be sent to you within 3 weeks of receipt of the samples. ALL identifying information is kept STRICTLY CONFIDENTIAL and is seen only by members of the research team at UPenn.


Should I pay to run a Quantitative Amino Acid Test on my Mastiff's Urine

The urine amino acid quantitation can be performed to detect elevated COLA amino acids (cystine, ornithine, lysine and arginine) in the urine to more precisely quantify the amounts of all amino acids, with the data that is used in the research study. Amino acid concentrations are considered elevated by comparison to normal dog controls. While this test can be used to confirm the results found on a nitroprusside test, it is an expensive test.


If your Mastiff’s nitroprusside test comes back positive, it would be very helpful to also submit a blood sample from the dog for the research study.  You can also offer to pay the extra fees to have the amino acid quantitation performed to confirm the diagnosis as that will help offset some of the research expenses that are associated with running these tests.


Urolith Stone Analysis Laboratories

There are several stone analysis labs in the United States, but we encourage and highly recommend that urinary stones be submitted to the Minnesota Urolith Center at the University of Minnesota Veterinary School or the Urinary Stone Analysis Laboratory at the University of California, Davis School of Veterinary Medicine for analysis.  These teaching universities are highly respected among Veterinarians and Researchers and the data they collect from analysis is periodically analyzed and published, which helps the researchers and veterinarians in practice.


The Minnesota Urolith Center offers FREE Quantitative Urolith (urinary stone) Analysis so please ask your veterinarian to submit your dog’s urinary crystals and stones to confirm that they are cystine.  It is also a good idea to submit the stones each time your dog has an episode of forming stones to verify that the new stones are also cystine.  In addition to providing free stone analysis, the University’s Lab also shares important data and statistics from the results with researchers to support health research projects.

Minnesota Urolith Center

Department of Small Animal Clinical Sciences

University of Minnesota Veterinary School

Telephone (612) 625-4221


Here’s information you can read before submitting a stone sample for analysis:

How to Submit a Sample

Sample Submission Checklist

Stone Analysis Submission Form






Cystinuria Urine Submission Form

Return To Cystinuria Home

Cystinuria Updates

Is Cystinuria A New Disease In Mastiffs?

Cystinuria Research & How You Can Help

Inheritance Of Cystinuria In Mastiffs

Cystinuria Testing Recommendations

Cystinuria Clinics

If Your Mastiff Has Cystinuria

Stories About Mastiffs With Cystinuria

 Frequently Asked Questions About Cystinuria & Links



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