Originally posted by Maja
Anyway it wont cause any harm to the dog
I disagree with this. Eating feces, especially feces with cat litter on it, can cause some serious problems. My girl Tasha found some cat feces in the yard a couple weeks ago and ate it before I could stop her. The next day she was vomiting and ill the entire day with acute gastritis, scaring the life out of me.

I'd definitely try to find a way to prevent the pup from having access to the litterbox.