Approximately 580 dogs have died and 3,600 reported sick in a mysterious connection with consuming Chinese jerky treats, according to a new update from the U.S. Food and Drug Administration. The problems date back as far as 2007, when FDA first began receiving a higher volume of reports of dogs exhibiting symptoms such as decreased appetite, lethargy, vomiting and diarrhea. The apparent commonality was a diet including various brand-name jerky treats, all of which were manufactured in China. Food Safety News reported on the issue in March 2012, speaking with several dog owners who said they lost their dogs to medical complications from days to years after they began eating the treats. The treats are commonly sold as “jerky tenders” or “jerky strips” and are primarily made with chicken, although combinations may also include duck, sweet potato, and dried fruit. FDA has conducted more than 1,200 tests on various brand-name treats in an attempt to discover some type of common contamination, but those tests have not revealed any clear cause of the illnesses. The agency sent inspectors to China last year to investigate several jerky treat facilities in person. Those tests included checking for a number of microbial contaminants, antibiotics, metals and pesticides. Some tests even examined DNA and nutritional composition. But nothing has yet stuck out to investigators as a likely cause. “This is one of the most elusive and mysterious outbreaks we’ve encountered,” said Dr. Bernadette Dunham, director of the FDA’s Center for Veterinary Medicine, in a news release. “Our beloved four-legged companions deserve our best effort, and we are giving it.” FDA is now asking pet owners and veterinarians to assist in the investigation by reporting any complaints linked to pet food. In an open letter to veterinarians, the agency has requested samples and information regarding potential illnesses related to the treats be submitted to FDA’s Veterinary Laboratory Investigation and Response Network, a network of diagnostic laboratories. The agency has also asked vets to distribute jerky treat fact sheets to pet owners and report any observations of pet illnesses related to jerky treats. In some cases, reports have said dogs fell ill within hours of eating the treats. Other customers have said their dogs have eaten the treats for years without any ill effects. In severe cases, dogs have suffered kidney failure, intestinal bleeding and a rare kidney disorder called Fanconi syndrome. A smaller number of cases involved collapse, convulsions or skin issues. Earlier this year, Purina and Milo’s Kitchen recalled several jerky treat brand names – including Waggin’ Train and Canyon Creek Ranch – because they contained trace amount of antibiotics that are approved in China and Europe but not in the U.S. FDA advises pet owners who observe symptoms after feeding jerky treats to dogs to stop serving the treats immediately, consider contacting a veterinarian, and saving the remaining treats and packaging for possible testing. In July 2012, FDA released an unprecedented collection of data on the 285 tests it had conducted on jerky treats up to that time. In an interview with Food Safety News, author and microbiologist Phyllis Entis criticized the agency for what she viewed as a lack of a systematic approach to solving the problem, calling FDA’s efforts at the time “scattered” and saying that the agency was not investing sufficient resources into the investigation. “To identify the root cause of this problem, FDA is meeting regularly with regulators in China to share findings,” the latest FDA update read. “The agency also plans to host Chinese scientists at its veterinary research facility to increase scientific cooperation.”