The U.S. Food and Drug Administration (FDA) has issued a warning to pet owners whose dog or cat has fallen ill after eating certain varieties of pet jerky treats, the agency reported Tuesday.

Within hours of consuming jerky treats made of chicken, duck, sweet potatoes, and/or dried fruit, pets have started displaying decreased appetites, decreased activity, vomiting, diarrhea (sometimes with blood or mucus), increased water consumption, and/or increased urination. Since 2007, the number of reported illnesses has totaled 3,600 dogs and 10 cats. Roughly 580 of those pets have died.

"This is one of the most elusive and mysterious outbreaks we've encountered," says Dr. Bernadette Dunham, director of the FDA’s Center for Veterinary Medicine (CVM). "Our beloved four-legged companions deserve our best effort, and we are giving it."

Both veterinarians and pet owners are being called upon to provide the FDA with information regarding their pets’ illnesses. Veterinarians may be required to provide blood, urine, and tissue samples from their patients for further analysis. Meanwhile, the FDA says it will distribute a letter to doctors that can, in turn, inform pet owners about home care. The consumer fact sheet will explain to owners how to get in touch with the FDA if they suspect their pet has fallen ill from the jerky treats. They can do so either by reporting the incident directly online or calling the FDA Consumer Complaint Coordinator for their state.

Severe cases of jerky-related pet illness involved kidney failure, gastrointestinal bleeding, and a rare kidney disorder. Approximately 60 percent of cases involved gastrointestinal illness, and about 30 percent involved kidney and urinary systems. The remaining cases reported various symptoms, such as collapse, convulsions, or skin issues among their pets.

Inspections of the facilities in China, those which produce the majority of jerky implicated in the illnesses, yielded no insights into the outbreak’s cause. Since 2011, more than 1,200 jerky treats have been lab-tested for a variety of chemical and microbiological contaminants, including antibiotics, metals, pesticides, and Salmonella. Nutritional composition and DNA testing have also been conducted.

U.S. law does not require pet food manufacturers to state the country of origin for each ingredient in their products, making sourcing the ingredients particularly tricky — and in cases such as these, actually dangerous.

“To identify the root cause of this problem, FDA is meeting regularly with regulators in China to share findings,” the latest report states. “The agency also plans to host Chinese scientists at its veterinary research facility to increase scientific cooperation.”

The FDA urges pet owners who still opt to give their pet jerky treats to monitor the animal’s health with extreme caution. At the slightest sign of illness, they’re advised to remove the jerky from the pet’s diet and save remaining samples for testing.

"Our fervent hope as animal lovers," says Dunham, "is that we will soon find the cause of — and put a stop to — these illnesses."