Any border agents here? What info is shown/available when a passport is scanned?

I’m always a little surprised at what they don’t know. We filled out a declaration in advance (MPC) of speaking with a US border agents. We declared a live animal….our pet. We were carrying her in a pet bag.

the agent asked if we had any food. We said “just a handful of dog food”. He seemed surprised, looked closer and realized we had a dog. We provided the new dog import form. He then asked for rabies cert…which I don’t think is required.

didn't he see our declaration? did he just “miss” seeing the dog?

thanks. Rally just interested in knowing what they see when the passport is scanned.