Basenji Health Information - Fanconi Syndrome

Description 

Fanconi syndrome is a disorder in which the kidney’s proximal renal tubules do not properly reabsorb electrolytes and nutrients back into the body, but instead "spill" them into the urine. Symptoms include excessive drinking (polydipsia), excessive urination (polyuria), and glucose in the urine (glucosuria.) If Fanconi is left untreated, muscle wasting, acidosis, and poor condition will also occur.

Untreated, a Basenji with Fanconi syndrome will generally die from the disorder. If caught early and put on the treatment protocol, affected Basenjis can do well.

Checking for Fanconi

The earlier the disease is detected, the less damage is done to tissues and organs. The vast majority of Basenjis with Fanconi "spill" glucose into their urine, although it is possible in very rare cases for a dog to have Fanconi and not spill glucose. It is generally recommended that Basenji owners test their dog's urine for glucose every month, starting at age 3. Urine glucose test strips (not blood test strips), such as those used by diabetics, are inexpensive and can be purchased at most pharmacies.

The strip should be placed in the Basenji's urine stream and then read as specified in the strip instructions. If it is not possible to place the strip in the urine stream, then the owner may need to catch the urine in a clean container. (Some breeders use a pie pan, ladle, or serving spoon.) A positive result (glucose present) suggests the possibility of Fanconi, but is not sufficient for definitive diagnosis. Owners should then go to their vet for further testing, including a blood glucose level.

Strip testing indicates only the current presence or absence of glucose in the urine. It does not definitively diagnose Fanconi, and it cannot predict whether or not a dog will later develop Fanconi. A dog that test strips normal now may later develop Fanconi. Additionally, a dog that test strips normal and does not have Fanconi does not mean it cannot produce offspring with Fanconi.

Because elevated urine glucose is also found in diabetes, Basenjis with Fanconi are often misdiagnosed with diabetes. Diabetes will show high blood glucose along with urine glucose. In Basenjis, a combination of urine glucose and normal or low blood glucose strongly suggests Fanconi syndrome. Venous blood gas studies can verify an electrolyte imbalance consistent with Fanconi syndrome. A veterinarian should evaluate dogs that have Fanconi symptoms but are not spilling sugar.

DNA testing for Fanconi

A linkage marker DNA test has been developed to test for the mutation for Fanconi syndrome. The mode of inheritance has been determined to be recessive.

The test can determine if a dog is a carrier, clear, or affected with a high degree of accuracy, and can predict that a dog will become affected prior to the development of symptoms. The test is available through the University of Missouri School of Veterinary Medicine.

All Basenji matings should have at least one parent that tests clear, so affected offspring are not produced. Breeders should test breeding stock. All litters should have at least one clear parent.

Pets can be tested to verify a Fanconi diagnosis or to help assess their likelihood of coming down with Fanconi. However, check with your breeder first - pets with a clear parent do not need to be DNA tested. Further, even if your dog is DNA tested clear or carrier, you should still strip-test, as there is a small risk of error with the linkage DNA test.

Onset and treatment

The onset of Fanconi is typically between four and eight years of age, although onsets as early as three years and as late as ten years have occurred.

In 1990 Dr. Steve Gonto developed a treatment protokol, based on the treatments human Fanconi patients receive. The protocol involves acid neutralization, and replacing the lost electrolytes and nutrients, using bicarbonate and other supplements in specified doses to re-establish the body's acid-base balance and keep electrolytes at appropriate levels. Dr. Gonto was given lifetime membership in the Basenji Club of America in recognition of the importance of his work.

The Gonto protocol was studied and validated for the veterinary literature by Jennifer Yearley, DVM, while she was completing her professional studies. This was an important step in expanding the awareness of the treatment. The protocol has been very successful in improving both quality and length of life for Fanconi-affected Basenjis. The disorder can be controlled by the protocol, but it cannot be cured.