Having reread it a few times I think it's a typo for car. Although such a misadventure could easily cause a person to be late returning to the vet to pick up their cat, having gone to get gas while a procedure was in progress.

However, here's the first "Maru and boxes" video, because you deserve a little nostalgic joy. https://m.youtube.com/watch?v=xdhLQCYQ-nQ

Sadly, Maru died last September but he had a long and happy life with lots of love.