The U.S. Food and Drug Administration on Tuesday released data from five-and-a-half years of laboratory testing on Chinese-made chicken jerky dog treats — products that received heightened attention in 2007 and late 2011 following upticks in the 1,000 consumer complaints written to the FDA regarding sickened or dead dogs who consumed the treats. The bottom line: After 285 tests on chicken jerky samples from around the country, the FDA still cannot determine what in might be harming dogs who eat these treats. Regardless, the investigation will continue and the agency is still receiving new complaints from dog owners, said FDA spokeswoman Laura Alvey in an email to Food Safety News. The data release follows mounting scrutiny of the FDA’s investigation, as Ohio’s Sen. Sherrod Brown and Rep. Dennis Kucinich have pressured the agency to prioritize the investigation and dog owners in at least eight states have filed a class action lawsuit against Nestle Purina, one of the treat manufacturers. Earlier this year, FDA officials inspected an unspecified number of chicken jerky facilities in China, but the agency has yet to release any further information on those efforts. At the very least, the data release shows that the FDA has been actively testing jerky treats since January 2007, but the data’s format makes the impetus behind each test unclear, said Phyllis Entis, microbiologist and author of eFoodAlert. While many of the tests appear to be conducted in response to consumer complaints, others appear to be related to testing done on pet treats linked to the melamine dog food recall of 2007. An unprecedented ‘Data Dump’ In a post on eFoodAlert detailing the ‘data dump,’ Entis called the release an “unprecedented” move on the part of the FDA, but questioned how helpful the information would be without more context: “The problem with it is that there’s no indication of which tests were a result of the melamine investigation, which were results of consumer complaints, which were routine surveillance, or why there were certain tests done to certain samples that weren’t done to others,” Entis told Food Safety News. The data show that some of the samples were tested for everything from Salmonella and E. coli to cyanuric acid and aflotoxins, but the available information gives little insight into how various tests were chosen for each sample. Along with that, the tests seem to be spread among six regional or municipal labs, as opposed to being led by one more centralized lab. On eFoodAlert, Entis attributed the lack of progress in solving the mystery to two deeper problems: There don’t seem to be enough resources being spent on the investigation, and there doesn’t seem to be a systematic approach to tackling the mystery. When asked to elaborate, Entis offered a number of critiques: There is no consistent package of tests run on each sample, so data appears spotty. The fact that 285 samples have been analyzed by half a dozen labs over more than five years – less than one sample per lab per month — speaks to the lack of resources focused on the task. “You’re not talking about an FDA central research lab getting involved. You’re not talking about a particular regional lab being tasked to this problem. It’s scattered,” Entis said. “There’s no systematic approach that I can see, looking at the results being reported — no significant amount of resources being focused on this specific problem area.” FDA trying new avenues Alvey, the FDA spokeswoman, told FSN that the information in the data release did not represent all of the testing the FDA has conducted, and that other FDA labs and collaborating institutions are working to identify the root cause of the reported illnesses. The FDA has several initiatives underway to investigate additional toxic substances for which standard methods are not yet available, Alvey said. If the root cause is found, the public will know and necessary recalls will take place, she added. Until then, the FDA cannot recommend a recall without finding tangible evidence of a contaminant. In March, the agency posted a government contract for a private laboratory to analyze the nutritional content of 30 dog treat samples, but the listing does not mean the FDA is handing off the investigation. The agency suggests dog owners who feed their pets jerky treats to watch for signs such as decreased appetite or activity, diarrhea or vomiting, and increased water consumption or urination. An FDA “frequently asked questions” page has been produced for dog owners concerned about the situation. Read it here. Solving mystery may take more creative thinking Entis provided one suggestion for how the FDA might, as she called it, start “thinking outside the treat bag.” From what she can conclude from the test results, Entis said the most promising lead might be an undeclared ingredient in 12 of the samples: a moisture-retaining substance called propylene glycol. While propylene glycol is on the FDA’s Generally Recognized as Safe (GRAS) list, it can be toxic at certain exposure levels. Knowing that, Entis wondered if propylene glycol may be reacting with other ingredients in a way the FDA has not suspected. Dow Chemical states that glycol may react with other products under heat or oxidation processes which could in turn produce unknown effects. What, Entis asked, might happen when jerky treats featuring propylene glycol are irradiated, as some pet treats are? “I’m no chemist, but thinking back to the melamine recall in 2007, it turned out not to be just a melamine problem that was making the dogs sick — it was melamine plus cyanuric acid,” Entis told FSN. When researchers finally combined melamine and cyanuric acid under the right conditions, they finally figured out was sickening dogs. Similar tests might need to occur this time around to discover the jerky treat problem, where five years of dead-end tests are beginning to suggest the problem might require deeper, more creative problem solving. In the meantime, few signs suggest that the complaints from pet owners will slow down. “What I’m trying to get at, using [propylene] glycol as an example, is that this is supposed to be very mildly toxic, so maybe the problem is not something as simple as a single component,” Entis said. “But if you don’t know what you’re looking for, you’re not going to find it. I think this is going to take returning to more fundamental chemistry and biology thinking.”