The most common reason pet foods are recalled is to potential for Salmonella, a harmful bacteria, to grow. Salmonella can cause terrible intestinal problems, from diarrhea, to vomiting and even systemic infection with fever, dehydration, aches and chills.
Where does the Salmonella come from? AKA where does it grow? Most dry foods are made more yummy by coating the kibble with animal fat (chicken fat, tallow, something along these lines). While the pet food may have a shelf life of 2 years, the chicken fat may have been close to expiration, so is was heated up and sprayed on the kibble. The chicken fat then goes bad, and Salmonella grows. (Ok, this is a simplification of the process, but you get my gist, right?) Food is recalled. Remember, pet food companies buy chicken fat by the tanker – this coats a whole lot of pet food – large recalls ensue.
Recalls are then for human health and safety – the humans may touch the food and get Salmonella infection. The concern is not for pet safety. That’s the way it is.