Although the food recall, and the effects it had on some pets, was unfortunate, it's not all that surprising. A lot of brands, including those more expensive, so-called premium dog foods, include animal by-products. Here is why these are not good.
The pet food industry is an extension of the human food and agriculture industries. Pet food provides a market for slaughterhouse left-overs considered "unfit for human consumption," and similar waste products to be turned into profit. This waste includes such appetizing things as intestines, udders, esophagi, and possibly diseased and cancerous animal parts. These items are considered animal by-products.
Usually, about 50% of an animal contains parts that are not fit for human consumption. So, in order to make some cash flow from the other half of the animal, it's processed into pet food and animal feed.
There is also some concern as to the cleanliness of processing these by-products. Since they aren't fit for humans, there are some thoughts that these parts aren't treated with same care and quality control measures as is the rest of the meat.
Now, there is no evidence as of yet that this is the cause of the pet food recall. However, with the way the pet food industry uses these foods unfit for humans, it's no wonder that a break-out such as this is possible. Here's hoping things will get better.