jrd

Juvenile Renal Dysplasia

http://www.upei.ca/cidd

related terms:
familial/hereditary/juvenile renal disease, familial/hereditary/juvenile nephropathy, renal dysplasia, hereditary nephritis, renal amyloidosis

What is familial kidney disease?
Several breeds of dogs are known to be affected by a wide range of kidney diseases that are proven or suspected to be inherited. In many of these disorders, the kidneys are apparently normal at birth but begin to deteriorate early in life (less than 1 year of age). While the underlying problem in the kidneys varies between breeds, the end result is the same - kidney failure for the dog, generally by 5 years of age, although the severity and rate of progression varies between breeds and between individual dogs.

For many of these disorders, inheritance is not proven. The term "hereditary" is used when the inheritance is known, and "familial" when the mode of inheritance is not known but the disorder occurs more commonly in related dogs than would be expected by chance.

Where the actual defect in the kidney has been identified, a more specific name (given below) may be used Often several names are in use for a particular disorder (see related terms above).

Breed	Disorder	Inheritance (if known)	(for veterinarian)
Bernese mountain dog	familial glomerulonephritis	thought to be autosomal recessive	membranoproliferative glomerulonephritis; immune-mediated
bull terrier	hereditary nephritis	autosomal dominant	defect is in the structure of the glomerular basement membrane
Cairn terrier	polycystic kidney disease	inheritance tentative (rare)	kidney tissue gradually replaced by fluid-filled cysts
Doberman pinscher	familial glomerulonephropathy	unknown	irregularities in glomerular basement membrane
English cocker spaniel	hereditary nephritis	autosomal recessive	abnormality in glomerular basement membrane
Lhasa apso, shih tzu *	renal dysplasia	thought to be autosomal recessive	abnormal differentiation of kidney tissue
Norwegian elkhound	familial nephropathy	unknown	tubulo-interstitial nephropathy
Pembroke Welsh corgi	renal telangiectasia	unknown	multiple dilated renal blood vessels
Samoyed	hereditary nephritis	X-linked dominant	abnormality in glomerular basement membrane
Chinese shar pei	renal amyloidosis	unknown, possibly autosomal recessive	amyloid deposition most disruptive in kidneys; other organs (spleen, liver, pancreas) can be affected but with minimal clinical signs; may also have intermittent fever and joint swelling
soft-coated wheaten terrier	renal dysplasia	thought to be autosomal recessive	abnormal differentiation of kidney tissue
soft-coated wheaten terrier	protein-losing enteropathy and nephropathy
* Renal dysplasia may also be inherited in the Alaskan malamute, chow chow, golden retriever, miniature schnauzer, and standard poodle.

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What does familial kidney disease mean to your dog & you?
The signs of kidney failure are the same in young animals as in older dogs. One of the earliest signs you may notice is that your dog drinks more and urinates more. (Sometimes in young pups, owners may not recognize excessive urination as such, but think it is due to the dog being slow to housetrain.) As more and more kidney function is lost, other signs develop including poor appetite, loss of weight, lethargy, vomiting, and pale gums due to anemia. Although the progression may be slowed by treatment, ultimately kidney failure is fatal.

For most of these disorders, dogs show signs of kidney dysfunction before 1 year of age, and their kidneys fail before 5 years of age. In pups affected at a very young age (less than 5 or 6 months), growth may be noticeably stunted.

Hereditary nephritis in bull terriers is an exception. Affected animals often show no signs until 2 years of age or more, and may not develop kidney failure until 8 years. In Doberman pinschers and Norwegian elkhounds, signs of kidney failure may also appear later in life (6 years of age).

In the samoyed, because inheritance is sex-linked, males are more severely affected. Male pups with hereditary glomerulonephropathy usually show signs by 2 to 3 months of age, and kidney function deteriorates rapidly, resulting in death by an early age (approximately 1 year). Although affected females still show some kidney dysfunction, it is less severe and does not progress to kidney failure. Even if only mildly affected, they are carriers of the disorder and should not be bred.

In Chinese shar-pei dogs affected with amyloidosis, amyloid (a type of protein) is deposited in the kidneys and other organs. Most of the time, the clinical signs you see relate to disruption of kidney function which eventually (by about 3 to 5 years of age) leads to kidney failure. Affected dogs may have intermittent fever and swelling and pain in their joints, especially the hocks.

Pembroke Welsh corgis with renal telangiectasia have episodes of blood in the urine as adults.

How is familial kidney disease diagnosed?
The signs described above can have several causes, including other inherited disorders such as a heart or liver defect. Your veterinarian will do blood and urine tests that will point to your dog's kidneys as the cause of the problem.

For the veterinarian: Typical signs of CRF include azotemia, hyperphosphatemia, isosthenuria, and nonregenerative anemia. Calcium concentrations are variable. Persistent proteinuria is highly suggestive of hereditary nephritis, even before any clinical signs are evident. Proteinuria is not a consistent sign in renal dysplasia.

In suspect bull terriers, repeated protein/creatinine ratios >0.3 provide supportive evidence for hereditary nephritis in dogs that are older than 2 years of age, but who show no overt signs of renal failure. This provides important information in decisions about breeding.

Male samoyeds with hereditary glomerulonephropathy develop proteinuria, glucosuria and isosthenuria by 2 to 3 months of age, and azotemia and overt renal failure by 6 to 9 months. Affected females (carriers) develop proteinuria at a young age but may never progress to renal failure.

In cocker spaniels with familial nephropathy, proteinuria is usually present by 4 to 6 months of age and is persistent and marked. This is followed by decreased growth, and the development of isosthenuria and azotemia.

There are 2 different familial renal syndromes in the soft-coated wheaten terrier - renal dysplasia (onset usually before 2 years of age) and protein-losing enteropathy and nephropathy (onset 2 to 11 years of age).

In Chinese shar pei dogs with renal amyloidosis, proteinuria is usually marked, although it may be mild or absent in dogs with renal medullary, but not glomerular, amyloidosis.

How is familial kidney disease treated?
There is no cure, but there are ways to slow the progression of kidney disease, which your veterinarian will discuss with you. These include making sure your dog always has access to fresh drinking water, feeding a special (high quality, low-protein) diet, and the use of some medications which help to support kidney function.

Your veterinarian will help you to recognize the signs that your dog's kidneys have deteriorated to the point where euthanasia becomes the best option.

For the veterinarian: In some cases, angiotensin converting enzyme inhibitors (such as enalapril) may delay the onset of azotemia, lower the blood pressure, improve renal blood flow, delay decline in glomerular filtration rate, and slow the rate of increases in proteinuria.

Breeding advice
Affected animals should not be bred, and neither should their parents. Any related animal being considered for breeding should be screened for protein in the urine, which is an early sign of kidney disease.

All bull terriers being considered for breeding should be screened by measuring protein/creatinine ratios ( a simple test requiring a blood and a urine sample). Ratios greater than 0.3 on 2 occasions more than a month apart, indicate potential hereditary nephritis. Kidney function in these dogs should be monitored, and they should not be used for breeding.

FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Resources
Ackerman, L. 1999. The Genetic Connection:A Guide to Health Problems in Purebred Dogs. AAHA Press, Lakewood, Colorado.
Lees, GE. 1998. Congenital renal disease in dogs and cats. ACVIM-Proceedings of the 16th Annual Veterinary Medical Forum, p 28-30.
DiBartola, SP. 1995. Familial renal disease in dogs and cats. In E.J. Ettinger and E.C. Feldman (eds) Textbook of Veterinary Internal Medicine, p. 1796-1801. W.B. Saunders Co., Toronto.
Gleadhill, A. 1997. Juvenile nephropathies in dogs and cats. In Practice. Vol 19(5):270-277.
DiBartola, S. 1998. Renal amyloidosis. ACVIM-Proceedings of the 16th Annual Veterinary Medical Forum. p. 23-24.
Grower, GF, DiBartola, SP. 1995. Glomerular disease. In E.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, p. 1760-1775. W.B. Saunders Co., Toronto.

This database is a joint initiative of the Sir James Dunn Animal Welfare Centre at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association

reprinted with kind permission from Alice Crook,
DVM Coordinator, Sir James Dunn Animal Welfare Centre
Atlantic Veterinary College University of Prince Edward Island

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