Fanconi Syndrome

What are the signs & symptoms that develop in affected dogs?

Symptoms of abnormal kidney function in affected dogs most commonly include increased urination (polyuria) and excessive drinking (polydipsia) in an attempt to replenish their water stores. Less often, dogs may have weight loss (despite a normal appetite), vomiting, and weakness.

When do signs and symptoms develop?

Affected dogs typically present with clinical signs of abnormal kidney function at middle-age with an average onset age between four to seven years of age. Glucose in the urine (glucosuria) without increased glucose in the blood (hyperglycemia) may be noted on laboratory testing before clinical symptoms develop.

How do vets diagnose this condition?

Diagnosis is made based on clinical history, physical examination, genetic testing, and ruling out other causes of similar symptoms. Serum chemistry and urinalysis as well as venous blood gas analyses are indicated to define the extent of the tubular defect and acidosis. Urinalysis typically reveals glycosuria without hyperglycemia and ketonuria. Additional urine metabolic screening from dogs with Fanconi Syndrome often shows a generalized aminoaciduria and lactic aciduria. While there is severe aminoaciduria, there is either no or only mild proteinuria.

How is this condition treated?

While Fanconi Syndrome is not curable, it is treatable. If an affected dog is not treated, the disease can progress to chronic kidney failure. A highly effective therapeutic protocol developed and modified over the years focuses on correction of the various losses with particular attention to bicarbonate, normalizing electrolytes and minerals, and providing a high quality diet. Dogs with Fanconi Syndrome diagnosed and treated early will usually have normal BUN (blood urea nitrogen) and creatinine values. Those diagnosed later in their disease will show some azotemia (elevated BUN and/or creatinine), which may require modification of the protocol to address both the Fanconi (failure to reabsorb solutes from the urine) and renal insufficiency (failure to lose toxic solutes in the urine).

What actions should I take if my dog is affected?

• Closely monitor your dog for changes in their drinking and urination patterns.
• Regular veterinary visits and laboratory testing will be vital to catching this disease at an early stage where it can be more easily managed.
• Dietary and medication recommendations are based on how clinically advanced the Fanconi Syndrome is. Follow your veterinarian’s recommendations.