Chicken jerky treats may be to blame for dozens of new reports of mysterious illnesses and some deaths in dogs, prompting a renewed warning for pet owners by the Food and Drug Administration.

At least 70 dogs have been sickened so far this year after reportedly eating chicken jerky products imported from China, FDA officials said. That?s up from 54 reports of illness in 2010. Some of the dogs have died, according to the anecdotal reports from pet owners and veterinarians.

FDA officials say they have not been able to find a cause for the illnesses. Extensive chemical and microbiological testing has failed to turn up a specific contaminant and officials did not identify a specific brand of treats. They note that the reports of illness have not conclusively been tied to chicken jerky products, also sold as chicken tenders, chicken strips or chicken treats.  

The new warning follows previous FDA cautions about chicken jerky treats in 2007 and 2008. But after a high of 156 reports of illness in 2007, the number of complaints dropped. Now, it's rising again.

Dog owners and vets are reporting that animals may be stricken with a range of illnesses within days or hours of eating chicken jerky, including kidney failure and Fanconi syndrome (a specific form of kidney failure).

Symptoms may include decreased appetite, decreased activity, vomiting, diarrhea, increased water consumption and increased urination. If dogs show any of these signs, stop feeding the animal the chicken jerky products, and seek veterinary help immediately.

Most dogs have recovered, officials said.

Illnesses can be reported to the FDA?s Pet Food Complaint site.