"This has been one of the most mysterious and elusive issues we've had to investigate," Hartogensis said. She said the investigation has been particularly complicated because researchers haven't been able to pin down what ingredient may be causing the problem and because many of the treats and their ingredients are imported. And not much is known about animal deaths. While autopsies on humans can often determine the cause of death, pet owners usually forgo expensive autopsies on their deceased animals.
Dr. Richard Goldstein of the Animal Medical Center in New York said he has been investigating the illnesses since they appeared to begin in 2007, and he is still treating dogs that seem to suffer from the mysterious condition. He was consulted on a case just last week, he said.
In his experience, many of the cases have been small dogs who are eating a large amount of treats. He said the illnesses are rare, so he usually knows immediately when a sickness is connected to the jerky.
He said most dogs he treated were fine if they stop eating the treats. That's why it's important for dog owners to know about the problem, he said.
"The word is not out," he said. "Some vets don't even know about this."