I have begun researching any dogfood related problems since the death of 2 dogs at my shelter. The vet said the one died of toxins. The other one died the day before and they did not do bloodwork on him. Another dog last week had bloodwork done when she was spayed and had elevated liver numbers.
I found this link about Nutro:
Illness, Death Dog Nutro Pet Food
I am sure other brands must be bad also!
Please be careful and watch your dogs for any signs of illness. The chihuahua died very fast and with no warning signs the day before.