Can one bag of food be bad?

I posted about my cats all having the runs. Well the vets office stated that if I just started a new bag, it could be a "bad bag of food." What is the likely hood that this would happen? I currently feel Royal Cannin for sensitive systems. I have been feeding this for several months now with no issue. Frankly it is one of the only dry foods that Isaac doesn't get the runs from. Just curious if others have had any experience with this?

Can't really hurt to try out a new bag just in case. If they get better, just throw out the old bag. If they don't get better, it's something else and you can probably go back to the old bag.

I'd still probably be taking a stool sample in for a fecal, and if nothing shows up on there, possibly bloodwork.

Unless the bag is damaged, I doubt it. They make this stuff in several thousand tons at a time. Making small amounts is not cost effective in the slightest. So either the whole run would be affected or just the damaged bag(s).

I don't know about that company but some are having problems meeting the FDA's new quality standards for salmonella. Production hasn't changed for some but everything must come back clean before it can be shipped out. Likely other companies and plants are going through the same measures.
I know these new standards are also getting plants shut down, so it is being taken seriously.

However, it's possible the food in the bag CAN get damaged. It doesn't take much of an air hole to let the food go stale, and it could even spoil if it's exposed to the right heat conditons, etc.

^Heat would spoil the whole pallet or even several being stored. Minor damage would be more likely to happen at the store as the spin wrap protects it before then (and if it's ripped open by a forklift while moving, that's not something easily hid).

The bag was not open when I bought it that much I know. The pet store I shop at is good about taking things back and if I thought it had been open I would have returned the bag. Now last week Jordan did open the food container and rip the bag open one day last week when he was really hungry. I did get one stool sample from Isaac, but I still need to get the others.

I have had an unopened bag of food be bad before. It was from a store I normally didn't shop at, so I think that it may have sat too long or not been stored properly. The store wasn't a great one and has since gone out of business. I remember I had stopped because it was closer than going to Petco (no Petsmart back then).