By Susan L Fleisher, email@example.com or firstname.lastname@example.org Copyright 1996, all rights reserved.
Table of Contents
* Breeds Affected by Juvenile Renal Disease
* Symptoms and Diagnosis
* Current Research
Breeds Affected by Juvenile Renal Disease
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.
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.
George Lees, DVM of Texas A & M University is currently doing research on Juvenile Renal Disease in Cocker Spaniels. Both VetGen, in Michigan, and the Canine Genome Project at the University of California, Berkeley, are searching for the gene marker(s) for the Juvenile Renal Disease seen in Soft Coated Wheaten Terriers.
Although progress is being made, waiting for DNA testing to become readily available is not a feasible solution to the problems of many genetic diseases. Selectively breeding away from carriers now is the only responsible action. In some instances, careful breeders have succeeded in largely eradicating some genetic disorders from their breeds. Success depends on a number of factors. Every puppy buyer must be encouraged to report any major illness back to the breeder. Breeders must have a clear understanding of the modes of transmission of genetic disorders that affect their breeds. Known carriers as well as possible carriers, (littermates and offspring of those discovered to be carriers) must be conscientiously kept out of the gene pool, or used very judiciously. A method of communication among breeders must be established.
Clearly, an open registry such as the open registry begun in July, l992 for Sebaceous Adenitis (SA) in Standard Poodles (this disease also occurs in other breeds) is an important step forward and an invaluable resource. Open registries as well as research databases in many canine diseases are being established at the Genetic Disease Control For Animals (GDC) in Davis, California. In Europe, open registries have made it possible for careful breeders to greatly reduce the number of cases of some genetic disorders.
An open registry would include the names of carriers of the disease as well as the names of dogs who are clear, those who when bred to a carrier did not produce any cases of the disease in a litter of significant size. Obviously, the early onset of Juvenile Renal Disease allows carriers to be identified much sooner than does a disease which manifests itself later in life.
Kruger, J.M., Osborne, C.A., et al. : Congenital and Hereditary Disorders of the Kidney. Veterinary Pediatrics Dogs & Cats from Birth to Six Months., 2nd edition. (J.D. Hoskins, ed.) W.B.Saunders, Philadelphia, Pa, 1995: pp 401-406.
DiBartola Stephen P. et al: Familial Renal disease in Dogs and Cats. Textbook of Veterinary Internal Medicine. (S.J. Ettinger, & E.C. Feldman, ed) W.B. Saunders, Philadelphia, Pa. 1995:pp 1796-1801.
Willis, Malcolm B: Genetics of the Dog. Howell Book House, New York, NY, 1989;p 356.
GDC, P.O. Box 222, Davis CA 95617. telephone or fax 419 735-5818
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