The company tries hard to ensure each store runs smoothly. This can change depending on the employees/manager/owner you work with. If you do a decent job and are friendly to everyone, then in my experience the environment is excellent. There is some pressure to keep up sales with certain goals to achieve very shift/week/month but they are certainly achievable with a little bit of effort. The stores generally only have a few employees so management works hard to create a team environment which benefits the store. If you have a concern about something in the store, whether it is a customer or fellow co-worker, bring it up to your manager and they will help you sort it out (if it's ongoing, they should schedule a team meeting to discuss).
It became toxic because there were too many people gossiping throughout the stores. It was the kinda job you should show up, do the work required, sell product and go home but not everyone could do that!
Most Pet Valu's are individually owned and it is like a small family once you get use to it. It is a great place to work if the right people have the right attitude.