deaf great danes can be extremely hard to train! The baby gate idea will be the best. but if you dont want to make your kitties jump everytime to go potty or get food, you should get one of
these baby gates
that way the kitties can have access always but not the dog.
Also baby gates and pet gates have come a lot way! They are now super easy to open and you can get them that dont stand out as much! And even the tallest great dane should not be able to just step over it! You should find one about waist high, and teach him early on no jumping (which is a good idea to teach any dane!) and no headbutting it!
NEVER feed the dane from the table or counter of course! Not so much because of the health problems, but because they can easily help themselves if they decide they like human food! Our last dane actually stole an entire pork chop off the plate on the counter...
Also a
Vibrating colar can be great to get their attention when you are working on training and out playing!
Also dont forget to elevate food and water bowls! And get a good bowl that will cause him to eat slower!
Good luck with your puppy!