The day we got our most recent dog, he was delivered by his previous owner along with some supplies, including a half full bag of his food. That night, we served him dinner and he sniffed at it then just looked at us, seemingly confused.

We called the previous owner to ask if she had any ideas - I know big changes like that can be confusing for a dog, but we didn't want him to starve! The erstwhile owner said "I don't know. Maybe the pieces are too big for him. Maybe break them up?"

That answer always amazed me. Until a few hours prior, she had been responsible for his sustenance and she was the one who provided the food we were trying to give him. If he required extra steps, fine, but you would think she would know and have provided instructions. (The transfer wasn't contentious - she was voluntarily moving out of state.)

I don't remember what we did that night, but for the few years he lived with us, he would never reliably eat any of the kibble we tried for him. He would usually eat it if we mixed in wet food, but my cats love wet food and he was kind of a wimp so a lot of times he'd just sit and sadly watch them eat until they were full and he got to have the leftovers.

(I did try to discourage this behavior from the cats, but I couldn't be there the entire very long time it took him to eat and he didn't like his crate so I couldn't isolate him for meals.)

However, he was never shy about human food. He knew he wasn't supposed to eat it, so if I set it on a TV tray next to me or whatever, it was safe ... But if I left the room with it there, when I came back the food would be gone, despite the mysterious fact that he was in the same spot where I left him.

I had my suspicions, but never did resolve that mystery ...