Have a year old Rough Collie (large dog) and a 14 week old Maine Coon kitten - so again large for a cat but still small compared to the dog.
They are getting on really well - almost too well. They enjoy quite rough play - pup will put his jaws round the kitten and mouth him, or put his whole front leg over kittens chest and lick him all over. Kitten doesn't try to get free and in fact if "rescued" goes straight back to the dog and grabs hold of his muzzle, or ears, or paw! It's funny to watch but don't know if I should be allowing it or constantly separating them. They both seem happy!