From Pet Food Industry magazine:
Australia suspends irradiation of cat food
Release Date: Tuesday, June 09, 2009
An outbreak in neurological disorders in cats has lead Australia to cease sterilization of cat food by irradiation. Scientific studies have suggested food irradiation as the source of the illnesses afflicting cats, but exactly how irradiation is causing food to be toxic to cats is unknown.
Ninety cats in Australia were afflicted with neurological disorders after they ate Orijen imported dry cat food, manufactured by Champion Petfoods, according to Dr. Georgina Child, a neurologist familiar with the cases.
Only Australia, which requires irradiation of pet food, has reported issues with Orijen cat food; all other countries who imported non-irradiated Orijen cat food reported no problems.