A mystery about what’s causing dogs to develop kidney disorders that mimic inherited Fanconi disease has just become more complex.

Researchers in Australia who have been studying the association between Fanconi-like syndrome and consumption of chicken jerky made in China have discovered several new cases in pets that have had no access to Chinese-made dried chicken treats.

The common thread in these five or six cases are dental chews — snacks given daily that are designed to clean dogs’ teeth.

Although there is no direct evidence that dental chews are the cause of the problem, some of the dogs have been given two types of dental chews, and all have had one brand called Veggie Dents, made by Virbac, according to Dr. Linda Fleeman, a senior lecturer in small animal medicine at the University of Sydney. 

The second brand that some of the dogs have had is Greenies, sold by Mars, Inc. “However,” Fleeman noted in an e-mail interview with the VIN News Service, “Greenies have been available in Australia for a while whereas Veggie Dents have only been here since February or March.”

Another common aspect among the cases is that the animals are owned by veterinarians or veterinary nurses, Fleeman said. “This is interesting because it means the diet history is very reliable and the owners are very attentive to their dogs’ clinical signs,” she said.

The symptoms are similar to those seen in Fanconi, a disease in which kidneys lose electrolytes and nutrients in urine rather than properly resorbing them in the body. Signs of the disorder include excessive drinking and urination (polydipsia and polyuria, or PUPD) and glucose in urine (glucosuria).

Most cases of Fanconi, particularly in Basenjis, are thought to be caused by a genetic defect. The non-inherited syndrome is also referred to as acquired proximal renal tubulopathy.

“We will have some more confidence in an association with Veggie Dents if all the dogs recover once the treats are withdrawn (although obviously any other treats that might have been fed alongside the Veggie Dents will be withdrawn at the same time),” Fleeman said Thursday. “I heard this afternoon that one of the cases is already much improved although still has PUPD and glucosuria.”

Michael Walsh, marketing manager for dental products at Virbac Animal Health in Fort Worth, Texas, said he was unaware of any potential link between Veggie Dents and Fanconi-like syndrome outside of Australia, and was unaware of problems in Australia until he was contacted this week by The VIN News Service.

Walsh noted that he received an e-mail from a colleague in Australia on May 11 asking if he’d heard any reports of Fanconi-like syndrome in dogs after being fed Veggie Dents.

“I said, ‘I have no idea what Fanconi is, so no,’ ” Walsh recounted. “This,” he added, referring to the interview with a reporter, “is the second encounter I’ve ever had with the word ‘Fanconi.’ ”

Walsh said he didn’t think anything of the inquiry from Australia because the colleague had noted that some chicken jerky products made in China recently had been recalled in that country, so the issue was fresh on pet owners’ minds.

“We had just launched the chew treat (in Australia),” he said, “so people ask a lot of questions (such as) ‘Is this another chicken thing, or a China thing?’ ”

Walsh said Veggie Dents are composed of corn, starch, glycerin, soy, rice, yeast, sorbitol, corn derivatives and water, and are manufactured in Vietnam.

He said the product has been sold in Europe and Japan for about two years, and was introduced to the United States last September.

Virbac is an international company that originated in France. Walsh said the plant in Vietnam is regulated by the European Commission, the executive branch of the European Union. He said the facility is audited every two years; most recently, two months ago.

Walsh said worldwide sales of Veggie Dents, primarily in France, England, Japan, Germany and the Netherlands, amount to more than $4 million a year. Since Veggie Dents were introduced to the United States last fall, the company has sold some 68,000 bags, each containing 30 chews.

The mystery of Fanconi-like syndrome has been lurking for nearly two years. 

In September 2007, the U.S. Food and Drug Administration’s Center for Veterinary Medicine reported receiving more than 70 complaints involving more than 95 dogs that were sick, possibly from eating chicken jerky, tenders, strips or treats.

The agency said it had “conducted extensive chemical and microbial testing” but had not identified a contaminant.

Researchers noted that melamine, an industrial chemical that widely contaminated pet foods in North America in 2007, was not the culprit.

Signs of illness associated with the chicken snacks included decreased appetite, lethargy, increased consumption of water, increased urination, vomiting and diarrhea. Most of the dogs appeared to recover, but some died.

As cases in the United States diminished, the problem increased in Australia. In December, KraMar Pet Company Pty. Ltd. recalled Supa Naturals Chicken Breast Strips, which are sold in Australia and New Zealand, after 15 sick dogs were found to have eaten those snacks.

As with the suspect products in the United States, KraMar’s treats were manufactured in China.

Fleeman was working with colleagues to identify the cause when the cases arose involving dogs that had not been fed any chicken products sourced in China, but had been fed dental chews.