Normally in the kidney, there is selective reabsorption of water, sugars, minerals, and amino acids so that these substances are not lost excessively in the urine. In this disorder, there is a defect in the tubules of the kidney where this resorption occurs. Loss of these normally conserved substances leads to electrolyte imbalances, dehydration, and other problems.
How is Fanconi syndrome inherited?
unknown
What breeds are affected by Fanconi syndrome?
This is a significant disorder in the Basenji breed, affecting 10% or more of dogs. It is also seen in the Norwegian elkhound, Shetland sheepdog, and schnauzer.
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 Fanconi syndrome mean to your dog & you?
Dogs that are affected with this disorder usually show signs anywhere from 1 to 7 years of age. The earliest signs are excessive drinking and urination, because the kidneys are unable to conserve water. Because of the loss of nutrients and electrolytes in the urine, your dog may experience weight loss and muscle weakness. The condition may worsen slowly over several years, or may progress rapidly to kidney failure with signs such as poor appetite, extreme loss of weight, lethargy, vomiting, and pale gums due to anemia.
Dogs with Fanconi syndrome are prone to urinary tract infections due to the sugar in the urine.
How is Fanconi syndrome diagnosed?
The signs described above can have several causes. 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: Early laboratory findings include low urine specific gravity, and glucosuria with normal blood glucose concentrations. Evaluation of urine for amino acids reveals generalized aminoaciduria. The defective urine concentrating ability represents a form of nephrogenic diabetes insipidus; isosthenuria or hyposthenuria may precede glucosuria. There may be mild proteinuria.
As the disease progresses, dogs will develop azotemia, hyperphosphatemia, variable metabolic acidosis (hyperchloremic), and hypokalemia (which may contribute to the muscle weakness sometimes seen).
Unlike other hereditary kidney diseases, the primary abnormality is functional with little apparent structural change. The kidneys are generally grossly normal, and lesions with light microscopy are variable and non-specific.
Primary renal glucosuria is an uncommon disorder in which there is glucosuria with normal blood glucose concentrations and otherwise normal kidney function. It can be differentiated from Fanconi syndrome based on the absence of other solutes (amino acids, electrolytes) in the urine. It has been found in the Norwegian elkhound and may cause urinary tract infections.
How is Fanconi syndrome 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 and, depending on the stage of the disease, feeding a special (high quality, low-protein) diet and the use of some medications which help to support kidney function.
For the veterinarian: Management of this disease includes control of metabolic acidosis (which may be difficult with sodium bicarbonate), antibiotic therapy for urinary tract infections, and medical management of chronic renal failure. Potassium citrate therapy provides both alkalinization and potassium supplementation.
Fanconi syndrome is an important problem in the Basenji breed, affecting 10% or more of dogs. Affected dogs should not be bred and, because the mode of inheritance is unknown, it is safest to avoid breeding either parent or any siblings. One problem for breeders is that the condition may not become evident until 6 or 7 years of age. Any Basenji being considered for breeding should have the urine checked for glucose, an early sign of the disorder.
It is hoped that the gene will be isolated in the near future, so that carriers of the disorder can be identified.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
DiBartola, SP. 1995. Renal tubular disorders. In E.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, p. 1801-1804. W.B. Saunders Co., Toronto.
Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: December 14, 2001.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.