It's highly unlikely that we would ever accept a sheet for a character like Krypto.

Not only is Krypto [i]heavily[/i] reliant on Superman given that he has next to no supporting characters of his own, but it would also create a precedent that I think I'd rather we didn't set. I've seen people write characters that can't speak before (Black Bolt, more often than not) with limited success, but I don't think it's really viable long-term in conjunction with the aforementioned lack of an independent supporting cast.

There's a reason Wittengstein said that if a lion could speak, we wouldn't understand him – and I think in Krypto's case, it probably applies.