I was thinking how nice it would be if pets that were full didn't show on the options for edible items much in the way they don't show for books if they have read them.

Because of the constantly changing nature of the huger levels I don't know if coding wise it would be possible or if it would cause to much strain on the servers or something.

Having 40 pets it sure would make it easier to feed them when I want to (mostly they live in the resort).

I like this idea if, as you said, it wouldn't be too complicated or straining on the servers. I rarely ever feed my pets and tend to keep them in the resort, but I'm sure this would be a nice feature for those who like to feed their pets.