Fanconi syndrome in dogs is a complex, proximal renal tubular defect that leads to inadequate resorption of many urine constituents and is ultimately renal failure. The cause of the syndrome is unknown, and research has yet to uncover the cause. Fanconi syndrome occurs primarily in the dog and can be either inherited or acquired. There is no definitive treatment for Fanconi syndrome in dogs but a treatment plan is guided toward supportive care.

What is Fanconi syndrome in dogs?

Fanconi syndrome in dogs is a complex disorder of the kidneys, specifically within the renal tubules. Fanconi syndrome occurs primarily in dogs and can be either acquired or inherited. The characteristic abnormality of Fanconi syndrome is excessive glucose reabsorption via the proximal renal tubule. This leads to excessive urinary excretion of glucose. Abnormal absorption of other substances is also possible, although this differs from dog to dog. The kidneys are responsible for the prevention of acid-base, protein, and electrolyte imbalances. In dogs with Fanconi syndrome, various elements may be lost from the urine, causing electrolyte, acid-base, and protein abnormalities.

What causes Fanconi syndrome in dogs?

Here we will break down the inherited and acquired causes of Fanconi syndrome in dogs. Recently, ingestion of beef, chicken, duck and vegetable jerky treats have been linked to Fanconi syndrome. The exact toxic mechanism or ingredient has not been identified.

Inherited causes of Fanconi syndrome

There is a high incidence of inherited Fanconi syndrome in Basenjis and Fanconi syndrome affects 10-16% of Basenjis. The defect is genetic with an autosomal recessive mode of inheritance. The severity of the clinical symptoms varies within the breed but typically, the clinical signs are profound. Affected dogs are usually between 4-8 years of age when they start to show symptoms of Fanconi syndrome.

Acquired causes of Fanconi syndrome

Acquired causes of Fanconi syndrome in dogs have been associated with leptospirosis, pyelonephritis, hypoparathyroidism, hepatopathy, and various toxicoses (e.g. ethylene glycol and mercury). Fanconi syndrome can also affect Labrador retrievers who have copper storage hepatopathy.

What are the clinical symptoms of Fanconi syndrome in dogs?

Signs range from mild to severe, and polyuria and polydipsia are the most frequent. Other symptoms that may be noticed include:

  • Diarrhea
  • Weakness
  • Lethargy
  • Weight loss despite a normal appetite
  • Poor hair coat
  • Urinary incontinence

How is Fanconi syndrome in dogs treated?

Currently, there is no specific, curative therapy for inherited Fanconi syndrome. In addition to identifying and eliminating the underlying cause (e.g. jerky treat ingestion), supportive care is needed for acquired diseases. If left untreated, Fanconi syndrome can lead to renal tubular acidosis, acid-base imbalances, electrolyte abnormalities, protein deficiency, dehydration, and chronic renal failure. Supportive therapy includes treatment for dehydration and electrolyte imbalances with fluids recommended by your veterinarian.

What is the prognosis for dogs with Fanconi syndrome?

In studies of Basenjis with inherited Fanconi syndrome, the median survival time was 5 years from diagnosis. For dogs with acquired Fanconi syndrome, many dogs can recover if the underlying cause is found and removed, or adequately treated.

Fanconi syndrome in dogs is a disorder of the kidneys that can be either inherited or acquired. The cause is unknown, but Fanconi syndrome has been linked to beef, chicken, duck and vegetable jerky treats. There is no cure for Fanconi syndrome, but a treatment plan is guided toward supportive care. Symptoms range from mild to severe, and left untreated, Fanconi syndrome can lead to renal tubular acidosis, acid-base imbalances, electrolyte abnormalities, protein deficiency dehydration and chronic renal failure. If you think your dog may have Fanconi syndrome, contact your veterinarian.