The Food and Drug Administration (FDA) is looking into why pet treats imported from China are sickening and killing dogs and cats in the United States.
On Wednesday, the US government agency said that since 2007, a reported 3,600 dogs and 10 cats have come down with "jerky pet treat-related illnesses" -- of which approximately 580 were fatal.
To gather more information, the FDA urged consumers to report promptly potential cases. It also asked vets to forward blood, urine and tissue samples for analysis.
"This is one of the most elusive and mysterious outbreaks we've encountered," said Bernadette Dunham, director of the FDA's veterinary medicine unit.
"Our beloved four-legged companions deserve our best effort."
Jerky treats are made with chicken, duck, sweet potatoes and dried fruit, but under US law pet food manufacturers don't have to declare the country of origin for each ingredient.
"Most of the jerky treats implicated have been made in China," it said, adding that it has visited jerky treat Chinese manufacturers as part of its ongoing effort to get to the root of the problem.
It urged pet owners to be cautious with jerky treats and to look out for such symptoms as decreased appetite or activity, vomiting, diarrhea, increased water consumption or increased urination.
Last January several jerky treats were pulled from the US market after very low levels of up to six drugs were discovered in certain made-in-China samples at a laboratory in New York state.
In 2007, after several dogs and cats fell ill and died, the FDA found contaminants in pet food ingredients imported from China, triggering a major pet-food recall in the United States and elsewhere.