Jerky treats for pets will soon be back on store shelves, even though federal experts have not figured out why dogs are dying. Consumers were warned to avoid the treats, but despite those warnings, the treats will be back in stores as soon as next month. Two of the top selling brands, Nestle Purina Pet Care, and Del Monte Foods corporation confirm they will resume sales. Nearly 600 pets, mostly dogs, died from eating chicken, duck and sweet potato products made in China. More than four thousand animals including cats, got sick after eating the jerky. The FDA sent letters to veterinarians nationwide last fall, asking them to treat and send detailed information about any animals that may have been sickened from eating jerky treats. Even though government scientists are no closer to figuring out the mysterious illness, they say they won't stop Nestle or Del Monte from reintroducing the treats. Jerky makers say there is no proven link between their products and the pet poisonings. FDA officials say they have no proof of contamination. Nestle says its line of waggin' train treats for dogs will be back on store shelves next month. It includes products from a supplier in china, and products sourced entirely in the United States. Del Monte foods say they'll resume selling Milo's Kitchen Chicken Jerky Strips and Chicken Grillers recipe treats in March, but says they'll use meat from the United States. Veterinarians and animal advocates are not happy. They're worried more pets will get sick once the products return to store shelves.