Here's a link to a Consumer Affairs article that says there are many dogs getting sick after eating Nutro food. Some have died. Though there is no hard evidence that the illness are caused by the food, it does seem a really big coincidence and one that warrents further investigation.
http://www.consumeraffairs.com/news04/2008/06/pet_food_recalls98.html
http://www.consumeraffairs.com/news04/2008/06/pet_food_recalls98.html