My first dog, when I was in college, was a wolfhybrid/newfoundland mix-clearly not a planned breeding! He was a really interesting mix of the two breeds and a truly amazing boy. He looked more wolf with the newfy's body. That was hands down, the smartest dog I've ever owned. We had him for nearly 12 years and have stories for days of the things he could and did do! He could open any door, to the point we had to put a slide lock up high on our pantry, he would turn on the tv when we were away, one day I walked next door to visit my neighbor- guess I'd been there too long, because Cody let himself out of our house, walked across the yard and let himself right into her kitchen! I would board him at my vet's, I came back from one vacation and the vet(who lived on property) told me about someone setting off his alarm, which brought him with his shotgun and the armed police inside to find Cody hanging in the employee lounge! He said he'd never had a dog escape before, so after that when he boarded they just let him roam at night! I truly could ramble on with Cody stories forever! He was my heart dog and I had him for nearly 12 years. He was nearly 200 lbs(and that was NOT all muscle-i was young and stupid back then and he loved people food). One negative quality he had was he absolutely hated kids! I can only imagine what a wolf and mastiff mix could be like-but I am thoroughly predjudiced about a would hybrid!