Cat Planet is actually in one of many parallel universes, which explains why they can talk. But If I made it to Cat Planet, we all can!
Dog Planet hasn't been discovered. If there is one, it would most likely be in a parallel universe as well.
You know I can read your mind, I'm psychic. I'm still discovering the universe, I might find a dog planet, but do you know how long it takes for me just to travel a freakin' lightyear? Give me a break!
And it is possible for humans to meow in a parallel universe, it just depends on where the universe is lined and placed in the 5th dimension.