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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
E-mail: [email protected])

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


We have made some significant progress with our Cystinuria Research this past year with the DNA submissions from families of affected dogs.  It is extremely important that owners and breeders of Cystinuria positive dogs submit blood samples for DNA analysis, along with additional urine samples and pedigrees to Dr. Paula Henthorn at the University Of Pennsylvania to be used in the Cystinuria Research. 

The researchers need blood samples to find the gene mutation(s) that cause Cystinuria in Mastiffs!

UPenn also needs more blood samples from actual cystine stone formers. Based on the SNP Chip gene mapping studies, they are running additional gene mapping DNA analysis on Cystinuria positive dogs that have also had Quantitative Amino Acid screenings and on dogs that have actually formed stones. If you have submitted blood from a dog that tested NEGATIVE OR POSITIVE on the Nitroprusside Urine Screening and that dog went on to form cystine calculi or stones, PLEASE NOTIFY Dr. Henthorn at UPenn on the change in status as it will benefit the research study to know this information when analyzing the dog’s DNA.  Even if your dog has never participated in the study  before, please notify Dr. Henthorn if your dog has formed cystine stones or your veterinarian has observed cystine (hexagonal crystals) in the urine. The researchers need to compare the phenotype or clinical symptoms of the disease in individual dogs to the gene mapping study data.

Current Cystinuria Research Projects

  • Grant 919:  Kidney Disease – Cystinuria:  Molecular Genetic Characterization of Canine Cystinuria for the Development of Carrier Tests
  • Principal Investigator: Dr. Paula S. Henthorn, PhD at the University of Pennsylvania
  • Sponsors: Mastiff Club of America, Karen and Jeffrey Flocker of New Beginning Mastiffs, and the Basset Hound Club of America

Abstract: Cystinuria is an inherited disorder that causes kidney and urinary tract stones in dog, man and other animals and has been documented in over 60 breeds of dogs. In humans, mutations in two genes (named SLC3A1 and SLC7A9) are found in affected individuals. While human Cystinuria was originally observed to be inherited as an autosomal recessive trait, more complex inheritance patterns, and their molecular origins, are currently being elucidated.  Based on our previous work, which developed tests to detect Cystinuria-causing mutations for Newfoundlands and Labrador Retrievers, breeds that have autosomal recessive forms of the disease, and for Australian Cattle Dogs, which have a more complex etiology for Cystinuria.  We will focus our efforts for the next funding period on experiments that test a hypothesis developed from our current work. In particular, we will concentrate on three breeds in which Cystinuria is more common, in order to understand the genetic basis of the most common form of Cystinuria in dogs, with the goal of developing carrier tests to be used for the elimination of Cystinuria in multiple breeds.

Click on this link for the latest Cystinuria research report update: 

AKC CHF Grant 919 Canine Cystinuria Progress ReportCystinuria Research ParticipationIf you have a dog that has tested positive on the nitroprusside urine screening test or that has ever formed cystine crystals or stones, or that is related to a dog that has Cystinuria, (parent, grandparent, offspring, or sibling), please participate in the Cystinuria Research Study by filling out the DNA Submission Consent Form (Updated Oct 22,2010) and send it along with blood and additional urine samples and a copy of the dog’s pedigree if it is available. Dr. Henthorn is also interested in receiving blood and additional urine samples from dogs that have tested positive by the urine nitroprusside test in the past, but have been neutered since the urine tested positive.  If your dog has formed cystine crystals or stones it is very important that you also attach a copy of the Stone Analysis Report or send a sample of an actual cystine stone to Dr. Henthorn if it is available.Dr. Paula Henthorn (Mastiff – Cystinuria Research)Section of Medical Genetics University of Pennsylvania School of Veterinary Medicine 3900 Delancey Street, Room 4030 Philadelphia, PA 19104-6010  Phone number required for FedEx: (215) 898-8894Please Send Dr. Henthorn Updated Medical Information On Your MastiffsIf you have a Mastiff that is part of the Cystinuria Research at the University of Pennsylvania and your dog was Cystinuria negative when it entered the research program and it has since formed cystine stones, please notify Dr. Henthorn as soon as possible and give her a full update on your dog.  The same is needed from dogs that have previously tested positive on the nitroprusside urine spot test that have gone on to form stones.  Dr. Henthorn needs to know which dogs in the research study have actually formed stones and which dogs have not formed stones to study the differences in the clinical symptoms and expression of the disease (phenotype) verses the genetics of the affected dogs (genotype). Cystinuria Diet StudyDr. Giger, at the University Of Pennsylvania’s School Of Veterinary Medicine (PENN VET) is studying the effects of regularly used diets and supplements on amino acid concentrations (particularly cystine) in the urine.  Please contact Dr. Giger at (215) 898-3375 if you would like to include your Mastiff in this important diet study. Kidney and Urinary Tract Pathology ResearchPlease consider donating your Cystinuria Positive Mastiff’s kidneys and urinary tract to the University of Pennsylvania after his death.  UPenn would like to study the urinary tracts of affected Mastiffs that have formed cystine stones and from Mastiffs that were positive on the nitroprusside urine screening test, but never went on to form stones.  For more information and instructions on donating your dog’s kidneys and urinary tract to research after his death, please contact Dr. Paula Henthorn at the University of Pennsylvania’s School of Veterinary Medicine.  She can give you directions to share with your Veterinarian so that your Mastiff can be a tissue/organ donor after his death.

Cystinuria Research Funding

The Mastiff Club of America has been financially supporting Canine Cystinuria Research through various grants sponsored by the AKC Canine Health Foundation using funds in the AKC CHF’s Mastiff Donor Advised Fund.  In 2004 the Mastiff Club of America formed The Mastiff Club of America’s Charitable Trust which is an IRS approved 501(3)c charitable organization which allows the contributors to make tax deductible donations as allowed by law.  These donations can then be used to support health research projects for Cystinuria and other disorders that can affect Mastiffs and they also allow us to offer educational health seminars and discounted health clinics. We encourage everyone to make donations to the MCOA Charitable Trust’s general account, but we have also set up a designated Cystinuria Account for those that would like to make donations that are specific to Cystinuria until such time as a DNA Test for Cystinuria becomes available for Mastiffs. At that time any remaining funds in the Cystinuria Account will be used to help fund other health projects as needed.  You can also make online donations to the Mastiff Club of America Charitable Trust’s General Fund through Network for Good by clicking on the link. 


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