The thing is that the quality of ingredients they use in pet food are not usually the kind that are suitable for humans. Mycotoxins is found in low-end grains through fungi matter, which is common as to create the bulk of dry food. Bowel diseases are normally caused by indigestable matters such as plant matters. The thing is that with pet food, the effects don't usually show up until their mid-life or the latter part of their life span.
What my family and I eat, our pets eat; we rarely, if ever, touch food that are toxic to them. The exception is for fish and herps, they get whole food for that.