HomeAbout AHFFoundation FAQBreeder EducationGeneral Health Issues In AiredalesBroad InstituteHow to Submit A Blood SampleDisease and DNA Testing Options for Airedales
Renal Dysplasia

Kidney dysplasia goes by many names, including renal dysplasia, progressive juvenile nephropathy, familial renal disease and most commonly as juvenile renal dysplasia (JRD). (We will refer to this condition below as JRD or juvenile renal dysplasia for ease of communication.) Dogs who are suspected to have kidney dysplasia or kidney failure should be examined by a veterinarian for proper diagnosis and treatment.

Dysplasia is defined as abnormal growth or development of cells or organs. In the case of JRD, the kidney fails to develop properly during embryogenesis in the womb. At birth, immature structures consisting of undifferentiated fetal cells or tissue types are found in the kidney, and are persistent throughout the life of the animal.

JRD can present itself with a wide range of symptoms and pathological findings. Definitive diagnosis of JRD is done by a wedge biopsy which reveals dysplastic lesions, including abnormal ducts, and glomeruli. Individuals with an abnormal biopsy can be asymptomatic, showing no signs of the disease. On the other hand, they may present with classic signs of chronic end stage renal failure, or somewhere between these two extremes. Given this broad spectrum of symptoms, affected individuals often go unnoticed, and remain in the breeding population. This is why development of a genetic test is necessary for the management and elimination of this disease.

Canine geneticists need blood samples from affected Airedales with Juvenile Renal Dysplasia. Please contact us with your information at airedalehealthfoundation@yahoo.com and/or send in your dog's blood sample (How to Send in Your Dog's Blood Sample) to the Airedale DNA Bank. Be sure to mark the condition of your dog and mark that the sample is to be used for research on kidney dysplasia. All information is handled confidentially.

Breeds Affected:
JRD is seen in Airedale Terriers, Alaskan Malamutes, Bedlington Terriers, Boxers, Bulldogs, Chow Chows, Doberman Pinschers, Golden Retrievers, Great Danes, Great Pyrenees, Irish Wolfhounds, Keeshonds, King Charles Spaniels, Miniature Schnauzers, Norwegian Elkhounds, Old English Sheepdogs, Portuguese Water Dogs, Samoyeds, Swedish Foxhounds, Shiz TzuAccording to Kenneth C. Bovee, DVM, of the University of Pennsylvania, shih tzus are the most commonly affected dogs, with up to 85 percent of the breed afflicted in the US), Lhasa Apsos, Soft Coated Wheaten Terriers, Standard Poodles, and Yorkshire Terriers. Other types of genetic renal disease are also well known in Rottweilers, Shar Peis, Miniature Poodles, Cairn Terriers, Welsh Corgis,Pekingese, Shetland Sheep Dogs, Collies, Beagles, Basenjis, Bull Terriers and Cocker Spaniels, among others. Similar forms of genetic renal diseases may have different modes of inheritance in different breeds. Other forms of familial and congenital renal diseases seen in the breeds listed above include Glomerulopathy, Amyloidosis, Polycystic kidneys, and Fanconi-like syndrome.

Symptoms

Early symptoms of Juvenile Renal Disease include drinking copious amounts of water, something that might not be readily apparent in a house with more than one dog, frequent urination, and dilute urine which has little color or odor. Some affected puppies leak urine, many do not. Often a puppy owner's earliest complaint is about the difficulty of housebreaking a puppy, only later is discovered to have JRD. The volume of water consumed, and, in some puppies, leakage of urine can make housebreaking a formidable task. As the disease progresses, vomiting, weight loss, anorexia, lethargy, and muscle weakness are seen. There is sometimes a chemical odor to the breath as a result of metabolic waste not being excreted by the kidneys.

In breeds in which juvenile renal diseases are seen, symptoms may be noted as early as a few weeks after birth; and affected puppies are almost without exception symptomatic before two years of age. Some puppies fail to thrive: most grow normally until symptoms appear. Puppies with renal dysplasia may appear clinically normal for extended periods of time before developing signs of chronic renal failure. The rate at which renal dysplasia progresses to overt renal failure depends on the severity of the initial renal lesions. Dogs commonly do not exhibit clinical signs of renal failure until less than 25% of renal function remains. A dog with renal dysplasia affecting only one kidney may be symptom free, and the dog may live a normal lifetime.

If a dog under two years of age is found to have an elevated BUN (blood urea nitrogen) and creatinine, and significant protein in the urine, as indicated by an increased urine protein:creatinine ratio, JRD should be strongly suspected. Abdominal palpation by a veterinarian may reveal small irregularly shaped kidneys. An ultrasound can be a useful diagnostic tool, since the kidneys are often atrophied and underdeveloped. It must be kept in mind, however, that kidneys from affected dogs may be normal size.

The most accurate method for diagnosing JRD is a wedge biopsy from one kidney taken any time after the second month of life, or a histopathologic exam after death. A biopsy or autopsy of a puppy less than two months of age would not be fruitful, since the normally immature kidneys cannot be distinguished from those affected by JRD. The slides should be examined by an experienced pathologist. There are a number of pathologists who have a considerable interest in this disease. It is not reasonable to expect most puppy owners who are not breeders, to agree to a wedge biopsy, since a more accurate diagnosis will not affect the treatment or prognosis, and since the necessary anesthesia is not without risk.

If the reduction in renal function is identified early, when only increased water consumption and urination are evident, medical management can be instituted immediately. Although the renal damage is not reversible, the quality and length of the puppy's life may be improved by early treatment.

Treatment

Treatments for the symptoms of JRD include a low protein and low phosphorus prescription diet, such as Hill's K/D. The predominant effect of the low protein diet is to minimize production of uremic toxins so that the patient feels better. Low protein diets may help extend life in dogs. Phosphorus is more important in this regard, since high phosphorus accelerates renal failure, and restricted phosphorus slows it down. K/D is low in phosphorus, so it remains a good food for dogs in this condition. In addition to diet, IV fluids can be administered to correct disturbances created by the retention of uremic toxins. Epogen can be prescribed to treat the anemia of chronic renal failure, resulting in improving the quality, and probably the length of life. Kidney dialysis for dogs is offered at several veterinary medical sites. The University of California, Davis, Veterinary Medical School is performing kidney transplants, but transplanted kidneys in dogs are commonly rejected, and involve an extraordinary expense and commitment. UC Davis will only do a renal transplant if the red cell cross matching and blood type is a perfect match. and if the tissue typing is also a perfect match. One of four healthy littermates of an affected puppy may offer such a match.

 

What is the Mode of Inheritance for RD?

The mode of inheritance of rd has been widely debated, as this disease can
present itself with a wide range of symptoms and pathological findings.
Definitive diagnosis of rd is done by a wedge biopsy which reveals dysplastic
lesions, including abnormal ducts, and glomeruli. Individuals with an abnormal
biopsy can be asymptomatic, showing no signs of the disease, On the other
hand, they may present with classic signs of chronic end stage renal failure, or
somewhere between these two extremes. Given this broad spectrum of
symptoms affected individuals often go unnoticed, and remain in the breeding
population. This is why development of a genetic test is critical to the
management and elimination of this disease. Further a genetic test can be used
to show the mode of inheritance .

Through pedigree studies, the mode of inheritance was finally revealed as
Dominant with Incomplete Penetrance.

What does Dominant with Incomplete Penetrance mean? 

Dominant with incomplete penetrance refers to a situation where an inherited mutation may or may not be expressed in an individual.

 

The traits that we see in an individual are collectively known as the "phenotype", while the "genotype" refers to genetic constitution or makeup of
an individual.

Penetrance refers to the frequency that the phenotype (or some characteristics of the disease) is observed. If, for example, the penetrance. is 75%, then the chances of offspring to develop a disease are 3 out of 4. In the case of rd, the penetrance is low with a penetrance. estimated to be about 2-5%. Therefore only a small number of individuals with the mutation will show signs of the disease. However, they can pass the disease on to their offspring. This is why a genetic test is critical to manage rd; this is the only way to
eliminate this disorder. There may be risk factors or triggers that are yet undiscovered that may increase the chances of an individual to develop rd.

A mutation is a permanent change in the DNA sequence of a gene, whether itis good, bad or neutral. Mutations that cause a genetic disease can be inherited as dominant where one bad copy of the gene is sufficient to cause disease or a phenotypic trait to be observed, or recessive where two bad or mutated copies of the gene are needed to cause disease or phenotypic trait to be observed.

All chromosomes exist in pairs in the nucleus of cells. Each pair is comprised of one chromosome from the sire and one from the dam. Therefore, every animal has two copies of every gene. In dogs there are 78 chromosomes, or 39 pairs.

 

Is there a TEST for determining heritability of RD?

DoGene RD Testing: Early in 2013, AHF was approached by DogGenes.  Their test for dogs at risk of developing RD is based on the following: After DNA sequencing six candidate genes, a possible set of mutations was finally uncovered in a gene in Lhasa apsos and Shih Tzus. These allelic variants (mutations) were located in the same region of the canine Cox-2 gene. Four variants have been found in breeds that are known to be afflicted with RD. Consequently a genetic test is now available for many of these breeds. If an animal has one or two copies of these mutations, they are at risk for developing the disease or passing it on to their offspring. They have a screening method that looks at the incidence of a COX-2 oxidase mutation as associated with renal dysplasia in canines. DoGenes had screened a number of European Airedales and gotten a large number of positives for the mutation. European breeders were concerned over the results, worried they may have a problem in the breed with RD. We were asked to support a study of U.S. Airedales to compare the results to the European Airedales and to get an idea of the mutation rate in U.S. Airedales.

The findings of the results showed an overwhelming number of positives for this mutation in U.S. Airedales. Between both studies, the screen method results are not specific enough to be useful at this time in identifying Airedales at risk for developing the disease or those at risk for passing RD down to litters in subsequent breedings.

At present, the DoGene Screening Method is not specific enough for helpful use in breeding away from issues of RD in Airedales.

 

Enter content here

Enter content here

Enter content here

Enter supporting content here