Fanconi Syndrome

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.

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.

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.

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).

Talk to your vet about your dog’s Fanconi syndrome result so you can plan appropriate monitoring and care.

Watch for early signs such as increased drinking and urination, and schedule regular checkups and lab work to monitor kidney function.

Your vet may recommend specific dietary changes or medications depending on how advanced the condition is. Following these recommendations closely can help manage symptoms and support your dog’s health.

It is important to note that Fanconi Syndrome has been suspected to occur secondary to consumption of certain jerky treats. Fanconi Syndrome can also be acquired secondary to infections, chemical additives, and certain medications. Even dogs without risk from this variant can develop Fanconi Syndrome: regular veterinary check ups and monitoring of a dog's health is key to catching and treating the first signs of Fanconi Syndrome.

Penetrance: Fanconi Syndrome is recessive, that is, a dog requires two copies of the variant to show signs of the disease from the variant. This variant was first described in Basenji.

Gene

FAN1

Inheritance type

recessive

Clinical category

Urinary

Citations

1. Johnson et al 2012

• Basenji