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Cystinuria in Mastiffs

Cystinuria is an inherited metabolic disease caused by a defective kidney transporter for cystine and some other amino acids. Because cystine readily precipitates in acid urine crystals and later calculi (stones) can form in the kidney and bladder. These calculi can result in serious illness. Cystinuric animals may show recurrent clinical signs of a urinary tract disorder from a few months of age until late in life. Doga may experience difficulty in urination, have blood tinged urine, pass calculi, or may be unable to void urine despite numerous attempts. Due to the male's urogenital anatomy, male dogs may become completely blocked. Their bladder gets extremely distended and is at risk for rupture.

Furthermore, the severe urinary back-up pressure caused by the blockage may result in kidney failure. These serious complications often lead to death unless the animal recieves immediate emergency and intensive care. Calculi lodged in the urethra may be flushed out or backed into the bladder. In some cases, calculi in the bladder, kidney or urethra may have to be removed surgically. Special diets and medications may be helpful in preventing recurrence of calculi, but their efficacy has not yet been documented in cytinuric dogs. Even treated dogs are likely to develope mild to life- threatening recurrences. Recently, a few mastifs have been found to have cystinuria. At least one of them has been used for breeding prior to the diagnosis. The mode of inheritence has not been determined in the mastiff breed. However, in humans and the Newfoundland breed cytinuria is inherited as an autosomal recessive trait. This means that diseased dogs of both genders have two mutants (diseased) genes. Their parents are either clinically healthy but carry a normal and mutant gene (carrier), or are also affected (cystinuric with two mutant genes).

Further studies are needed to confirm the autosomal recessives mode of inheritance in the mastiff breed. Since show and breeding animals have been diagnosed with cystinuria, this disease may be as common as in the Newfoundland breed. Cystinuria has also been identifid in many other breeds,

The diagnosis of cystinuria can be made by using our specific urinary screening test method, the nitroprusside spot test. This test requires only a small amount of urine. You will find the simple instructions for submission enclosed. Furthermore, we can also analyze the voided or removed calculus even when only pinpoint in size for cystine. These tests are very reliable. In contrast, examination by the veterinarian of the urine for cystine crystals is not reliable, since theses crytals are not always present in urine.

In order to assist Mastiff breeders and pet owners, we are offering our urinary screening test for cystinuria, urine or calculi, for a limited time. Any information or test results will be kept strictly confidential. This test is accurate in identifying cystinuric dogs (two mutant genes). Asymptomatic carriers (one mutant gene) presently cannot be tested by this test. However, certain dogs are known carriers. Parents of affected cystinuric dogs are either carriers or affected, and littermates of affected dogs can be affected, carriers, or clear (two normal genes). For instance, any offspring from a stud dog that is known to be affected is a carrier or may even be affected.

Also, any mastiff dog can be checked for cystinuria, we particularly recommend testing the following dogs:

• Mastiffs with suspicious clinical signs, for example, difficulty or inability to urinate, blood in urine, calculi in bladder, urethra or kidney. relatives of known cystinuric or carrier dogs.
•  Mastiffs used for breeding.
• All mastiff puppies ages 4 weeks and up. This screening prevents the sale of any affected puppies and anguish of cystinuric pet owners. Furthermore, if a puppy is found to be affected, it would be known that the parents are either carriers or affected as well.

Being able to make a diagnosis of cystinuria has many benefits:

• A specific diagnosis can be reached in dogs with suspicious signs.
• Healthy appearing Mastiffs will be recognized to have cystinuria.
• Mastiffs with cystinuria can be appropriatly managed.
• Cystinuric Mastiffs as well as carriers can be taken out of the breeding program, thereby preventing the production of affected dogs in the future.
• Affected puppies will not be placed (sold) to new owners who would have to deal with the suffering and expense of an affected dog.
• Finally, the screening of all Mastiffs used for breeding and showing and their offspring will provide valuable information on the prevalence of cystinuria in this breed and eventually help to improve the health of the Mastiff breed.

Submission

Using the form that we have developed for cystinuria in the Newfoundland, you can submit calculi, liquid urine in a tube, or (less prefered) urine dried on a special filter paper. The extent of the cystine defect in the Mastiff has not completely defined, therefore, liquid urine samples in a tube are prefered.

Collect urine in a very clean container, for instance, sterile glass or plastic tube with appropriate lids from your local veterinarian.

Puppies may be stimulated to urinate by applying a wet cotton ball in their urogenital area. In this case, urine may be directly absorbed onto the filter paper (provided by us) or again collected in a small clean container. Soak the unmarked end of the labelled filter paper with urine and allow to dry on a cellophane or household aluminum foil for 3 hours.

You may wish to store the liquid urine sample in the freezer until you have collected all samples for shipment.

Shipment: Ship by overnight mail in appropriate mailer, preferably with an ice pack. Complete the submission form (and a check payable to Trustees, Univ. of Penn. $18/dog). Mailing address is:
Dr. Urs Giger/ Cystinuria
Veterinary Hospital, University of Pennsylvania
3900 Delancey Street, Philidelphia, PA 19104-6010
phone: 215-898-3375
fax: 215-573-2162
e-mail: giger@vet.upenn.edu

The results will be sent to you within 10 days of reciept of the samples. All in information will be kept strictly confidential.