Federal health officials are warning pet owners to be cautious about feeding their dogs jerky treats as they continue to investigate a treat-related illnesses that has left nearly 600 dogs dead and sickened more than 3,000 others.

The Food and Drug Administration on Tuesday issued an alert to consumers about the illnesses and deaths tied to jerky treats from China. Officials say the exact cause of the illnesses remains unknown.

"This is one of the most elusive and mysterious outbreaks we've encountered," Bernadette Dunham, director of the FDA's Center for Veterinary Medicine, said in a statement. "Our beloved four-legged companions deserve our best effort, and we are giving it."

The agency has received reports from pet owners and veterinarians about jerky pet treat-related illnesses affecting 3,600 dogs and 10 cats in the U.S. since 2007. Approximately 580 of those pets have died, according to a news release.

The FDA noted a decrease in reports of illnesses earlier this year after a number of pet jerky treats were pulled from the market. Officials say the number of reports may have declined because fewer jerky treats were available to consumers.

Symptoms observed within hours of eating the treats include decreased appetite, vomiting, diarrhea, decreased activity, increased water consumption and increased urination, the agency said. Severe cases have involved kidney failure and gastrointestinal bleeding, the FDA said.

The agency urges owners of pets showing symptoms to consult a veterinarian and save any remaining treats and treat packaging for possible testing.

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

The Associated Press contributed to this report.