By Dr. Lisa Sarvas and the AMSC Health Committee, March 2009
(Reviewed by Dr. Cathy Brown, Nephropathologist, UGA)

What It Is: A disease of abnormal kidney development, resulting in kidney insufficiency or kidney failure. It can be due to a hereditary cause.

Clinical signs: Increased urination and thirst, poor growth and development.

The kidneys function to filter waste products out of the body and to maintain water and electrolyte balance. Dogs with JRD will have un-concentrated urine and may have elevated kidney values despite excess water intake. Anemia, renal osteodystrophy and other typical findings of chronic renal failure may also be present.

Age of diagnosis: From post weaning to adulthood, depending on severity of disease.

How is it diagnosed? Blood work, urinalysis, renal ultrasound.

Dogs with JRD will have unconcentrated urine and may have elevated kidney values despite excess water intake. Ultrasound may show poor kidney structure. The gold standard of diagnosis is the renal wedge biopsy. Reported histological lesions in affected dogs include interstitial fibrosis (which is often severe), the presence of immature or “fetal” glomeruli and chronic, mild inflammation.

Is A DNA test available? There is currently a DNA test on the market.
The research showing the mutation identified and the test development has not been published or peer reviewed, so the AMSC cannot comment on the validity or usefulness of the test at this time. Hopefully as more is learned about the research in the future then this could change. Renal dysplasia research is also occurring at MIT-Broad Institute with focus on the Shih Tzu and Boxers, and at VetGen with a focus on Shih Tzu and Lhasa Apso.

Heredity: Currently unknown!

It has been postulated to be of dominant with “incomplete penetrance”, which means that simple genetic inheritance of a dominant mutation doesn’t always produce disease, or autosomal recessive. The disease occurs equally in males and females and is believed not to be sex linked.

How common is it in the Miniature Schnauzer? Currently unknown!
There are confirmed cases of JRD in the Miniature Schnauzer. However, the exact prevalence of the disease is unknown as many cases are incompletely diagnosed and many are not reported. We ask that all owners of diagnosed cases notify the American Miniature Schnauzer Club Health Committee.

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Juvenile Renal Disease, also known as JRD, occurs in a number of dog breeds including the Miniature Schnauzer. Renal dysplasia is a disease of abnormal kidney development that can result in kidney disease. In medical terms, this is defined as kidney insufficiency or kidney failure. Clinically, this may manifest as increased urination, thirst, difficulty housetraining, weight loss, and poor growth or weight gain. Additional signs such as poor appetite, lethargy, vomiting, diarrhea, poor hair coat and muscle mass may also be present.
Renal disease is diagnosed by a veterinarian through evaluation of blood work, urinalysis, and renal ultrasound and JRD is suspected when renal disease occurs in a young dog or other causes of renal disease (infection, toxic insults) are ruled out (C. Brown, Personal communication). Dogs with JRD will have unconcentrated urine and may have elevated kidney values despite excess water intake. Ultrasound may show poor kidney structure. The gold standard of diagnosis is the renal wedge biopsy, which is a surgical procedure. Evaluation of the biopsy via histology will show interstitial fibrosis (which is most severe in dogs with severe renal disease), the presence of immature or “fetal” glomeruli and chronic, mild inflammation (C. Brown, personal communication).
Dogs with the disease may show signs as early as post weaning or as late as several years of age. In mildly affected cases, dogs may develop renal insufficiency in adulthood or remain clinically normal and live a full life term with only moderate polyuria (increased volume of urine). In severe cases puppies may develop clinical signs as young puppies and die of disease in a matter of weeks or months. This is because the disease may be present in varying degrees of severity at the level of the kidney. The kidney has excessive extra function and therefore disease has to be severe or progress significantly in order for the patient to show signs of disease. Normal kidney values only prove that there is more than 30% of normal kidney function present, and cannot be used to rule out kidney disease.
There is currently a DNA test on the market to identify a mutation thought to be associated with the disease. The research on the identified mutation and the test development has not been published or peer reviewed. Therefore, the AMSC cannot comment on the validity or usefulness of the test at this time. Hopefully as more is learned about the research in the future then this could change. Renal dysplasia research is also occurring at MIT-Broad Institute with focus on the Shih Tzu and Boxers and at VetGen focusing on the Shih Tzu and Lhasa Apso.
JRD in Lhasa Apsos and Shih Tzus was being investigated long before the AMSC became aware of any potential disease concerns in the Miniature Schnauzer or became involved in supporting research. Much of the scientific information centers on those breeds as they lead the way in research and disease awareness. Research in the Shih Tzu has shown that there is a high rate of non-clinical affected dogs in the breed and this causes much concern for all breeds with clinical cases of disease. Little is currently published on the JRD in the Miniature Schnauzer. So, one of the goals of the AMSC Health Committee is determining the prevalence of JRD in the Miniature Schnauzer. We as a breed organization lack data on the actual rate of clinical and sub-clinical JRD affecting our population. This is in part due to the fact that some dogs with lower rates of fetal glomeruli (a possible diagnostic indicator) may remain asymptomatic and are never diagnosed as having renal disease. A renal biopsy remains the gold standard to definitively diagnose clinical and subclinical JRD.
The AMSC health committee has enlisted the aid of Dr. Cathy Brown, at the University of Georgia, in Athens. Dr. Brown serves on the International Renal Standardization Study Group which employs the use of three diagnostic modalities, as used in human nephropathology, to accurately characterize glomerular disease. There is no doubt that we have procured the services of an internationally recognized nephro-pathologist in our goal to elucidate the prevalence of renal disease in our breed. She is the AMSC’s preferred pathologist to perform histology on renal wedge biopsy samples. By using the same pathologist, we hope to reduce variation in interpretation of the samples and also enable Dr. Brown to provide the committee with statistical information on disease prevalence in the samples she has received. Although fetal glomeruli are normally present in puppies under 8 weeks of age, Dr. Brown is also willing to evaluate histology on wedge biopsies for this age group in the event information can be gained from doing so. Dr. Brown requests that if a dog is getting a necropsy, that the renal wedge should still be taken as soon as possible after death to avoid degradation that might complicate evaluation of the tissues. Veterinarians must submit the wedge biopsy.
If the only wedge biopsies performed are on dogs that die from renal disease, this defect could appear to be more prevalent than it actually is within the population. That is why it is important that we obtain data from the population at large if we hope to gain some perspective on how prevalent JRD is in the Miniature Schnauzer. This should be a club-wide and breed-wide effort in data collection to optimize results.

In summary, the Health Committee asserts the following points & recommendations:

a. We ask that the Miniature Schnauzer owners and breeders become aware of the disease and discuss this disease with their local practitioner.
b. While a small number of breeders have been severely affected by this disease, the prevalence of JRD in our breed population is unknown. (For those who have faced it, JRD has had a devastating impact on those breeding programs.)
c. The Health Committee recommends the members submit all DNA and wedge biopsy results to the committee for inclusion in our database. Information from the breed at large is vital in obtaining a clear perspective of ANY disease in our breed.
d. Wedge biopsies should be obtained on all deceased animals irrespective of cause of death for analysis by Dr. Cathy Brown to help determine disease prevalence in our breed.
e. Please have biopsies (preferably wedge) sent to: Dr. Cathy Brown at the University of Georgia, School of Veterinary Medicine, Veterinary Diagnostic and Investigational Laboratories, Athens Georgia. If your veterinarian needs information on sample submission, they may contact Dr. Cathy Brown ( This e-mail address is being protected from spam bots, you need JavaScript enabled to view it ) at Athens Veterinary Diagnostic Laboratory, 706-542-5568.

References and Further readings

AMSC Health Committee (2009.). AMSC Position paper on juvenile renal dysplasia, AMSCOPE . Available from American Miniature Schnauzer Club.
Bovee ,K (2003). Renal Dysplasia in Shih Tzu Dogs. 2003 World Small Animal Veterinary Association Congress Proceedings, Bangkok, Thailand. http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2003&PID=6602&O=Generic
Fleischer, S. (1996) Juvenile renal disease. VetProf. Available http://www.vetprof.com/clientinfo/juvenilerenal.html
Giger, U.(2002) Diseases of the kidneys. 2002. World Small Animal Veterinary Association Congress Proceedings. http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2002&PID=2621
Morton L., Senecki R., Gordon E., Sopiarz, R., Bell, S., Sakas ,P. (1990). Juvenile renal disease in miniature schnauzer dogs. Vet Patholology, 27,455-458.
Swailes & Ledgerwood P. (2004,), Detection of renal disease in the miniature schnauzer. AMSCOPE. Available from the American Miniature Schnauzer Club.

Wedge biopsy from a Miniature Schnauzer with JRD. It is stained with a stain that shows scar tissue as blue, and demonstrates the segmental nature of the lesion. This slide was provided to Dr Brown courtesy of Dr. George Lees.