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What is Fanconi Syndrome?

Not often seen, primary Fanconi syndrome is a genetic kidney disease of Basenji dogs that appears in adulthood (on average between 4 and 8 years of age) and is autosomal-dominant. The disease is the result of an issue with the proximal renal tube and occurs in about one tenth of adult Basenjis. Since the disease is typically not discovered until the dog is older, the condition is often passed on to offspring as it was not known that the parent was affected.

The condition can also occur as a secondary disease as a result of kidney issues from your dog having consumed toxins, developed infections or experienced drug reactions. If no cause can be found for the renal tubular dysfunction, it is considered idiopathic Fanconi syndrome.

Should your dog experience this condition, the proximal renal tubules of his kidneys will not reabsorb electrolytes and nutrients back into his body like they are supposed to. Rather than reabsorption occurring, the electrolytes and nutrients will be released into his urine. Fanconi syndrome is progressive. If it is not treated it will lead to renal failure as a result of proximal renal tubular acidosis and ultimately be fatal. The earlier the disease is diagnosed and treated, the less damage will be done to his tissues and organs.

Fanconi syndrome can be primary, secondary or idiopathic; the result of proximal renal tubular dysfunction, in this condition the kidneys won’t reabsorb electrolytes and nutrients into the body as expected, instead releasing them into the dog’s urine.


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Symptoms of Fanconi Syndrome in Dogs

Dogs with Fanconi syndrome may demonstrate the following symptoms:

  • Lethargy
  • Vomiting
  • Lack of interest in eating
  • Diarrhea
  • Excessive thirst
  • Excessive urination
  • Weight loss
  • General weakness
  • Seizures (in 15% of cases)

The severity of symptoms will be dependent how much of specific nutrients have been lost as well as whether your dog has experienced kidney failure. As the disease progresses, poor body condition may be seen. Should a dog develop the syndrome when he is very young, which is rare, abnormal bone development may occur.


Primary Fanconi syndrome is a genetic renal disease that is autosomal-dominant and occurs rarely in Basenji dogs. Also occurring as a secondary disease, the condition can develop as a result of kidney issues from your dog having consumed toxins, developed infections or had a reaction to drugs that together have led to the proximal renal tube being damaged, leading to a disruption in kidney function. Secondary Fanconi syndrome has been linked to primary diseases to include:

  • Congenital renal dysplasia
  • Heavy metal exposure
  • Abnormal collection of cells or tissues in the kidneys
  • Hypoparathyroidism

Idiopathic Fanconi syndrome is when no cause has been determined; this has been seen in the Norwegian Elkhound, Labrador Retriever, Shetland Sheepdog and Minature Schnauzer.

Causes of Fanconi Syndrome in Dogs

It is believed that the deficiency in the proximal renal tube is because of a problem in endocytosis by the proximal tubule of glucose and proteins that the glomerulus filters. There may be some variance when looking at the condition’s different forms. When the condition occurs after renal issues that occurred from ingesting toxins, experiencing infections or drug reactions, it is considered a secondary condition.

Diagnosis of Fanconi Syndrome in Dogs

If you notice troubling symptoms in your dog, you will want to schedule an examination of your dog with your veterinarian. Along with conducting a physical examination, your veterinarian may conduct a urinalysis as well as other diagnostic tests. 

Should changes in your dog’s blood be seen (high levels of liver enzyme, high levels of nitrogen containing compounds like urea for example) it can point to Fanconi syndrome. A urinalysis will usually show amino acids in his urine as well as the excretion of glucose; if there is glucose in your dog’s urine but the level in his blood is normal, this can be indicative of Fanconi syndrome.

To confirm the diagnosis, your veterinarian will seek to exclude Leptospirosis as a cause of your dog’s symptoms, which will require a negative serology for the condition. Subclinical diabetes will need to be ruled out as well. A renal biopsy will be required to confirm proximal renal tubular nephropathy.

Treatment of Fanconi Syndrome in Dogs

In order to manage the disease, treatment must be developed based on the severity of the reabsorption defects experienced by a particular dog. While it is not possible to reverse the atypical reabsorption of solutes, your veterinarian will work to develop a treatment that will support a normal acid-base balance in your dog’s body. This may include potassium supplements and management of kidney disease through nutrition. Supplementation will need to be provided throughout your dog’s life. You will want to be sure to always provide your dog access to fresh water as the greater number of solutes in his urine will result in osmotic diuresis and the inability to concentrate urine.

Recovery of Fanconi Syndrome in Dogs

When treatment is provided before renal damage is severe, your dog will have a good prognosis. Follow up appointments will likely be requested so that your veterinarian can confirm that treatment is working and make any changes to the treatment based on the follow up examination and testing. You will want to work closely with your veterinarian to ensure the best outcome for your dog. While the disease cannot be cured, it can be controlled.

Fanconi Syndrome Questions and Advice from Veterinary Professionals

6 Years
Moderate condition
-1 found helpful
Moderate condition

Has Symptoms

Weight Loss
Frequent Urination

Our 6 year old basenji, Rajah, was diagnosed with Fanconi syndrome a year ago. Just recently we have noticed rapid weight loss, a strong breath odor, and she lets out a cry occasionally when jumping off the couch. We are bringing her in to the vet this week to see what is going on but didn’t know if there was any advice you can give me until then. It breaks my heart seeing her sick and she had been doing good up until now.

Dr. Michele King, DVM
Dr. Michele King, DVM
1607 Recommendations
I hope that Rajah is okay. With her history and signs, your veterinarian will want to check her kidney enzymes and see what is happening with her. Until you have some lab work, it is difficult to say what might be going on with her.

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Irish Aussie poo mix
18 Months
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Bloody Urine, high glucose in urine
Bloody Urine

Our vet diagnosed our 1 1/2 yr old Irish Aussie poo with Fanconi Syndrome on her second hospital stay. Her first symptoms were lethargic, refuse to eat, red gums, weight loss, blood in her urine, dehydrated. She was hospitalized for 4 days because of her symptoms and after blood/urine tests she had some kind of uti infection, high urine levels and glucose in urine. She was tested for leptospirosis , which was beg. After receiving fluids/meds, blood normal, urine normal. 8 days later she was hospitalized again with same symptoms but a little worse. This is when she was diagnosed with Fanconi Syndrome. Same thing occured as far as multiple tests, kidney sonogram and the only thing found was high urine levels and glucose in urine. 5 more days in the hospital given meds/fluids back to normal sent home with enrofloxacin, sucralfate, doxycycline. The vet said she really doesn’t know exactly what’s wrong still wrong. Her appetite was back, playful, acting like herself. 4 days later the symptoms are back. We can’t let Stella go through this suffering and not have definitive answers and treatment. (Side note... we don’t give her beef jerky and she did not ingest any toxins. She is very pampered and the only time she is away from family is 2 days a week at doggie daycare with our other dog)

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3317 Recommendations
There are three main types of acquired Fanconi Syndrome (chicken jerky treat ingestion, gentamicin nephrotoxicity and idiopathic) and an inherited form as well (most common in Basenji dogs but may occur in other breeds). Treatment depends on the underlying etiology and overall management of the condition with diet and supplementation, there is no one fits all for treatment. Regards Dr Callum Turner DVM

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6 Years
Moderate condition
1 found helpful
Moderate condition

Our 6yr old Basenji recently was diagnosed with Fanconi. We have her on the protocol for fanconi syndrome and have treated her UTI. The problem is she is unable to control her peeing. Every time she lays down to sleep she pees excessively where ever she is. Is this something that can be reversed or a result of damage to the kidneys. As is we can't keep this up.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3317 Recommendations
Unfortunately the urinary issue is going to continue to occur, due to the loss of solutes in the urine there is an increase in water which is also excreted leading to polyuria and polydipsia. Cases vary in severity and should be treated on a case by case basis and managed accordingly. Regards Dr Callum Turner DVM

My vet suspects my dog (senior male rottweiler) also has Fanconi. He has some mild incontinence (dribbling, constant need to urinate due to the volume of liquids he's drinking to flush his kidneys). I've been using belly bands which have saved my furniture and sanity- my buddy will be with me as long as his quality of life is good. I'd recommend checking out this option (I really like the ones Paw Legend makes)- they make them for females too and perhaps this could help you manage Athena's condition!

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