Jerky treats made in China are making pets sick all over the country, according to the Food and Drug Administration.
The FDA reports more than 3,600 dogs and 10 cats have become ill from eating the treats since 2007.
The treats have not been recalled because experts cannot figure out why they are making the animals sick.
Thousands have become sick and nearly 600 dogs have died after eating jerky treats.
The treats making animals sick are sold under a variety of brand names, but all are made in China.
The treats are sold as jerky tenders or strips, made of chicken, duck, sweet potatoes or dried fruit.
Pets affected are known to experience decreased appetite, decreased activity, vomiting, diarrhea, increased water consumption and increased urination.
More severe cases have had kidney failure, gastrointestinal bleeding, convulsions and even death.
Most dogs who had severe reactions are small and ate a large portion of the jerky.
The FDA says the more cases reported, the closer it will be to solving this mystery.
"Not only narrow it down to which product, but also which ingredient in that product and then to see how many different products that ingredient's in, " said veterinarian Renee Smith.
The FDA says it is meeting frequently with regulators in China to share its findings and hopefully figure out the problem.
Veterinarians and pet owners who see a pet become sick after eating jerky treats are asked to report the case to the customer complaint coordinator in their state.
It also asks that they save the treats they believe made their pets sick for testing.