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Cases of Fanconi-like syndrome still occurring in dogs

Mystery remains, following long FDA investigation into jerky treats

July 2, 2020 (published)
By Anna Lewis

Anna Alyse Photography
Rue developed Fanconi-like syndrome last fall. In a spate of cases that began more than a decade ago, the renal disorder was linked to consumption of certain pet treats. While reports have declined in recent years, cases are still occurring. Rue recovered after she stopped eating suspect treats and received medical care.

Alicia Smith was concerned. Her usually happy, healthy 6-year-old Pomeranian, Rue, was acting differently. Smith noticed early last October that Rue was constantly thirsty, drinking lots of water and needing to urinate much more than usual. When Rue, who would never pee on a hard surface, urinated on the patio, Smith knew something was wrong.

From her home in Massachusetts, she searched the internet about Rue's signs. "Pretty much everything that goes with excessive urination and excessive drinking is not good," she said, "so I made a vet appointment."

Initially, the veterinarian suspected diabetes because Rue had a high level of glucose in her urine, Smith recounted. But after finding that the glucose levels in her blood were normal — which would not be the case if she had diabetes — the veterinarian suspected the dog had Fanconi syndrome.

Fanconi is a disorder of kidney function that results in excess excretion of glucose, electrolytes and amino acids in urine. It can affect people, as well as dogs and cats. In dogs, Fanconi usually is seen in certain breeds, such as basenjis, as a hereditary condition. In 2007, veterinarians became aware of Fanconi-like signs in multiple other dog breeds without a recognized genetic predisposition, and alerted the U.S. Food and Drug Administration, prompting an investigation. The chief suspect: jerky treats.

But 13 years later, investigators for the agency have been unable to pinpoint the cause and have largely stopped trying. While a few brands, such as Milo's Kitchen, reportedly have reformulated their products, jerky treats remain widely available in stores, and some dogs still are getting sick. Rue is a case in point.

After taking her to a specialist and confirming that Rue had Fanconi, Smith was advised by the doctor to cut all treats out of her pet's diet. She'd been giving the dog Greenies dental chews and Dentley's chicken-wrapped rawhide treats purchased from PetSmart. She had given Rue one or two of the Dentley's treats a day and one Greenie treat every other day. Though jerky treats have been a top suspect in investigations into treat-acquired Fanconi, other types have been implicated as well, including dental chews in Australia.

Smith said that after eight weeks without treats, plus treatment with sodium bicarbonate and a supplement to replace lost vitamins and minerals, Rue began to return to normal. She had less glucosuria (glucose in the urine), polyuria (excessive urination) and polydipsia (excessive drinking).

This reinforced Smith's and her veterinarian's suspicion that Rue's illness stemmed from treat consumption. "I think it was a result of what she was eating, and now that we've taken that away, it's kind of removed the symptoms of Fanconi," Smith said.

'People think it went away'

In its last public update on the subject, in May 2016, the FDA said reports of illness related to consumption of jerky pet treats — which numbered in the thousands — had fallen markedly. Signs of the illness included decreased appetite, lethargy, vomiting, diarrhea, polydipsia and polyuria.

In the course of a decade, the agency said, it had received 5,200 reports of illness related to the consumption of chicken, duck and sweet-potato jerky. Most reports concerned dogs; some reports involved multiple animals. More than 6,200 dogs had been sickened, and of those, more than 1,140 died. Twenty-six cats and three people had been affected, as well.

To date, investigators have not found a definitive reason for the illnesses and cannot say with certainty that jerky treats are the cause. FDA spokesperson Anne Norris said the number of reported illnesses associated with jerky treats has waned and no longer is at a level that warrants focused attention. "Therefore, the FDA has dialed back its use of investigative resources on jerky pet treats to focus on other types of pet food product complaints,” she said.

Dr. Sherri Wilson, an internal medicine consultant for the Veterinary Information Network, an online community for the profession and parent of the VIN News Service, said in an interview, "People think it went away and that we don't have a problem with it anymore." But she worked as a consultant on a case as recently as this May, she said. And while she doesn't consult on as many cases as she once did, Wilson said she doesn't believe the problem is solved.

She added that she's unsure whether the smaller number of cases she's consulting on indicates a real reduction in cases or whether veterinarians simply are more familiar with the phenomenon and no longer seek specialist advice.

Dr. Urs Giger, former director of PennGen, a University of Pennsylvania School of Veterinary Medicine genetic testing facility that is one of the few places in the United States offering a test for inherited and acquired Fanconi, has followed treat-associated cases since they were first recognized in 2007. Giger also has published research on the subject. During the past decade, PennGen received test requests from all over North America, as well as Europe, including Austria, England, Germany and Switzerland, he said.

Today, the number "has drastically been reduced," Giger said, but not to zero.

"We received far less cases over the past years. However, we still see them, which is of concern because, unfortunately, despite the effort by FDA’s Vet-LIRN to identify toxins … they have not been able to find it,” he said in an interview. Vet-LIRN is the FDA's Veterinary Laboratory Investigation and Response Network.

After learning about Rue's case, VIN News searched VIN message boards for mentions of jerky and Fanconi since 2016, which netted more than 100 hits. Among those, VIN News found 29 possible cases of treat-associated Fanconi-like syndrome, more than 40% of which were in the Northeastern U.S. The rest of the cases were elsewhere in the U.S., as well as in Canada, Finland, New Zealand, the Netherlands and the United Kingdom. Nine of those cases were confirmed by urinary testing, history of treat consumption and reversal when the patients stopped eating the treats. The remaining 20 were clinically suspected based on either urinary testing and a history of treat consumption; or glucosuria that resolved when treats were discontinued. Fourteen of the 29 had positive Fanconi tests.

Six of the 29 cases occurred this year. One of those patients was seen by Dr. Ann Hill of Pittford, New York. In February, Hill examined a 5-year-old Manchester terrier presenting with excessive urination, excessive drinking, lethargy, lack of appetite, weight loss and vomiting. The dog also had a high urine glucose level. Hill learned that the dog had been eating chicken treats from Trader Joe's.

Hill posted the case on a VIN message board for colleagues' opinions, then sent for a Fanconi test at PennGen, which came back positive. Hill said the dog has since shown clinical improvement.

Wilson, the VIN internal medicine consultant, said she's "appalled" that the ongoing jerky treat issue is not better publicized and she is distressed when she learns that friends have been feeding their dogs such treats.

"I think they should all be off the shelves," Wilson said. "They do hurt dogs."

'Little dogs, big doses'

In cases described by veterinarians on the VIN message boards in the past four years, dogs consuming treats made from chicken, duck and sweet potato, as well as beef, experienced sometimes severe signs of Fanconi and/or gastrointestinal upset.

Dr. Katherine James, a urology/nephrology consultant on VIN, said causes of acquired Fanconi-like syndrome include exposure to heavy metals such as copper and lead. The variety of possible causes can make it difficult to pinpoint a particular cause in acquired Fanconi cases, she said. Therefore, when diagnosing gastrointestinal and urinary problems, she generally recommends obtaining from pet owners a complete diet and exposure history of the patient.

Jerky-associated cases usually involve smaller dogs. That's because of what James refers to as "little dogs and big doses." In other words, small dogs eating problematic food get a bigger dose of the problem than big dogs eating the same amount of the food.

In Giger's experience, the main determinants in dogs developing Fanconi are breed or size, regardless of age or sex.

Early on, the problem was widely ascribed to chicken jerky made in China but at the time, almost all chicken jerky was made in China. Therefore, it was unclear whether the problem was something in the manufacturing process in China or the nature of jerky itself. Later, as companies shifted to domestic jerky manufacturing, cases surfaced involving U.S.-made treats.

An FDA report updated in 2018 noted that manufacturers are not required to list the source country of product ingredients.

Relations between Chinese plants and the FDA have at times been strained. During a 2012 FDA inspection of a plant that manufactures some of the treats associated with complaints of illness, a Chinese government official refused to allow inspectors to collect samples.

Giger said: "I think all the companies that had these implicated pet jerky treats have very diligently been looking at their products, and while many products have been recalled, there are obviously still some that might be tainted with something unknown that might be so detrimental."

VIN News contacted PetSmart, which markets the Dentley's treats that Rue consumed, to ask whether the company was aware of recent health problems associated with the treats and its store policy on jerky treats. Spokesperson Erin Gray responded by email with a company statement: "While we stopped sourcing jerky products from China in 2015, we continue to rely on the FDA for guidance. We will continue monitoring all sources of information and take additional action if necessary."

Kenya Friend-Daniel, national director of public relations for Trader Joe's, said by email that the company takes food quality and safety matters "seriously."

"We will never leave to chance the safety of the products we offer, and we always err in the side of caution — proactively addressing any and all issues," she said. "We take action quickly, aggressively investigating potential problems and removing product from sale if there is any doubt about its safety or quality." 

VIN News was unable to reach anyone for comment from Mars Petcare, the maker of Greenies.

Greenies, Dentley's and the Trader Joe's chicken treats are all labeled or said to be made in the U.S.

What did the FDA find?

The FDA actively investigated the issue from 2007 until 2016.

Using products bought from stores and samples provided by the owners of sick dogs, its researchers tested treats for a variety of toxicants and other substances that could cause health problems, including pathogenic bacteria, toxic chemicals, preservatives, antibiotics and excessive vitamin D. While Smith did not file a report with the FDA, both brands of treats her dog consumed were named by other complainants in the agency's investigation.

An FDA report in 2013 speculated about some possible causes, including the physical characteristics of the treat and some potentially toxic substances.

To test whether Fanconi symptoms could be caused simply by the makeup of the treats, researchers put the treats in a device meant to simulate a stomach. They found that the treats did not break down easily. According to the report, “This could indicate that some of the dogs' digestive disturbances are caused by the tough nature of the dried product. Dogs do not chew their food; rather, they gulp whole jerky treats or minimally chew them before swallowing.”

Continued testing from 2013 to 2015 did not uncover a definitive culprit, either. Researchers again tested for compositional problems, as well as certain chemicals, metals, antibiotics and radioactivity. 

The results were inconclusive. Still, the FDA continues to state, "Jerky pet treats are not required as part of a complete and balanced diet for your pet."

While regulators did not find a proverbial smoking gun, two large treat brands experienced fallout in court. Nestlé Purina PetCare Co. and its subsidiary Waggin' Train were the target of a class action in 2014, which ended with a $6.5 million settlement. Separately, Milo's Kitchen, a brand formerly owned by Del Monte Foods and now owned by the J.M. Smucker Co., settled a class action in Missouri for $600,000.

Prognosis: usually good

One question many pet owners have is whether dogs recover from treat-related Fanconi. James, the urology/nephrology consultant on VIN, said recovery can take a few months, and in some dogs, the polyuria and polydipsia don't resolve, and some are left with chronic kidney disease. But many dogs who, like Rue, stop eating the suspect treats and receive therapy to replace lost nutrients, can make a full recovery.

As the FDA states, "Dogs diagnosed with FLS [Fanconi-like syndrome] usually improve or recover with appropriate veterinary care and removal of the jerky pet treats from the diet; the death rate for FLS is low when treated."

"Thank goodness," Wilson said, "most of the time, we can turn it around."


VIN News Service commentaries are opinion pieces presenting insights, personal experiences and/or perspectives on topical issues by members of the veterinary community. To submit a commentary for consideration, email news@vin.com.



Information and opinions expressed in letters to the editor are those of the author and are independent of the VIN News Service. Letters may be edited for style. We do not verify their content for accuracy.



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