Case Study: Fanconi-like Syndrome in Dogs

Dr. Kay Foster
November 18, 2022

“Ethel” is a FS 13yo Chihuahua mix who presented for a routine exam to update vaccines. Physical exam was fairly normal, given the signalment, with nuclear sclerosis in the eyes and dental calculus and periodontal disease within the mouth. As part of the routine exam, internal organ function and complete blood counts were performed. Internal organ function revealed abnormal renal values and hypophosphatemia. Complete blood count showed dehydration. Other findings were within normal limits.

HCT 58.83% (37-55)
BUN 47 mg/dL (7-27)
CREA 2.0 mg/dL (0.5-1.8)
PHOS 2.4 mg/dL (2.5-6.8)

To continue work up of the azotemia, a free catch urine sample was collected. This demonstrated dilute urine in face of the dehydration and azotemia and glucosuria.

Urine Glucose 100
USG 1.020

The findings were discussed with the owners, pointing out that the blood work appeared to indicate the kidneys were not filtering properly. The glucose in the urine was discussed. In most cases, glucose in the urine, or glucosuria, occurs with diabetes. However, glucose in the blood work was within normal range (for reference, blood glucose was 107mg/dL (70-143)). The owners stated that Ethel had been acting normal at home. However, water intake and urination were difficult to monitor as she was let outside to urinate. Ethel ate regular AAFCO certified dog food; however, she was encouraged to eat every meal with jerky treats on top of it.

Further work up of the renal status was evaluated with SDMA, UPC, and blood pressure—all of which were normal. Given the lab work findings and history of jerky treats—a tentative diagnosis of jerky treat induced Fanconi-Like Syndrome (FLS) was given.

What is Fanconi Syndrome?

Fanconi Syndrome has historically been seen as a genetically inherited disease seen most commonly in the Basenji breed. It is a disease that causes proximal renal tubular acidosis marked by the inability to absorb particular solutes when filtering the urine. The solutes most commonly affected are glucose and bicarbonate; however, phosphate, potassium, calcium, sodium, and magnesium can also be affected.

Common signs seen at home include increased thirst and urination caused by osmosis of hyperglycemic urine. Also reported is general lethargy and vomiting. Clinical physical exams reveal weight loss and dehydration. Chemistry panels reveal azotemia, hypophosphatemia, hyperchloremia, and hypokalemia. It should be noted that glucose and proteins are usually normal in blood work. Urinalysis generally shows glucosuria and low USG. Further work up to evaluate renal damage should be done as well can a venous blood gas to establish the acid-based status. The University of Pennsylvania offers a specific confirmation test based off of a urine sample.

Treatment consists of stabilizing the patient with a bicarbonate supplement to normalize acid-base status and rehydration. Some internists may follow a specialized plan called the Gonto Protocol. Long term care involves electrolyte supplementation and establishing good hydration practices.

Fanconi-like Syndrome and jerky treats

Starting in 2007, the FDA began noting a pattern in illnesses in pets consuming jerky treats. As of 2015, the FDA received more than 5,200 complaints in association with these treats—most commonly made of chicken, duck, or sweet potato. Many of the products have been noted to be sourced from China. These complaints are not limited to Fanconi and also commonly include bacterial and toxin contamination. As of 2018, it was estimated that more than 360 dogs were reported to the FDA to have Fanconi-Like Syndrome (FLS).

The CDC investigated approximately 100 cases of renal illness in dogs exposed to jerky treats. While there have been attempts to identify the cause of FLS in relation to these treats—a definite answer has not been found. Research has included, but not been limited to, screening for pathogenic bacteria such as Salmonella, heavy metals/elements such as arsenic and lead, antibiotics, and pesticides. Slips and surges of cases have been seen as products are removed and re-introduced to market shelves. The periods of most reported cases occurred between 2011-2014. Most cases have been in North America, Europe, and Australia. Curiously, while most cases are sourced from China—the reporting in Asia is generally low despite equality on consumer availability of these products. However, veterinary case studies have been published in Japan, and the expectation is that with increased awareness and reporting, these numbers may rise.

Most dogs seen with Fanconi-like Syndrome are small to medium breed dogs with daily exposure to the jerky treats. Prognosis is good; most dogs return to normal readings shortly after removal of the treats from the diet. However, cases of lasting kidney damage have been reported.

Both pet owners and veterinarians can report suspect cases via the FDA Safety Reporting Portal or the local FDA Consumer Complaint Coordinator. Be prepared with supporting information on pet’s signalment (age, breed, gender status), basic lab work including Chem/CBC and Urinalysis, how long and how frequently the pet has been exposed to the treat, what other products the pet consumes, and name and lot number of the treats themselves.


Hooper AN, Roberts BK. “Fanconi syndrome in four non-basenji dogs exposed to chicken jerky treats”. J Am Anim Hosp Assoc. 2011 Nov-Dec;47(6):e178-87. doi: 10.5326/JAAHA-MS-5602. PMID: 22058368.

Durocher, Lawren. “Fanconi Syndrome: A Review.” Clinician's Brief, Nov. 2012,

“FDA Investigates Animal Illnesses Linked to Jerky Pet Treats.” U.S. Food and Drug Administration, FDA, Center for Veterinary Medicine. 2018,

Yabuki, Akira, et al. “Acquired Fanconi Syndrome in Two Dogs Following Long-Term Consumption of Pet Jerky Treats in Japan: Case Report.” The Journal of Veterinary Medical Science, The Japanese Society of Veterinary Science, 3 May 2017,

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