No matter how clean the litter box is my dog gets in and played, making a huge mess. plus he helps "clean" it too. Ive tried everything I can think of to break him of it, but its not working.
Your best option is moving the litter box somewhere he can't get to it. Can you put a baby gate on the door to the room it's in? Some gates have a small animal pass through, though a cat generally doesn't have any problem jumping a gate, so that may not be necessary.
Agreed. We've always had to use gates and just keep it out of the dogs access, without limiting the cats. Unfortunately, I now have a dog smaller than my cats, but she doesn't jump as high as they do, so the gate still works.
The best way to keep the dog out of the box is to physically place it where he can't reach it. You have two options: get a new box or place it out of his reach. As far as the box is concerned, some with covers totally confuse the dog and they don't try again. Look at some large pet stores or specialty pet websites to explore options there.
If your dog is really persistent, that probably won't work. You're going to need to put it somewhere he absolutely can't get to it. Think about raising it onto a coffee table, placing a baby gate that the dog can't pass (but the cat can), putting it in a bath tub in a spare bathroom, or putting it on the patio with a kitty door. You'll have to get creative, but there's definitely an arrangement that will work! It'll be worth it for finally being able to accept those puppy kisses (and lowering the risk of parasites and infection!).