I have a 4 month old black lab/american bulldog mix and a 2 year old pug/terrier mix. My Lab/Bulldog mix is very playful and will sometimes will grab onto my terrier mix cheeks trying to get her to play. I noticed yesterday that he is starting to scratch her cheeks and now they're all red and irritated. I'm working on getting him to not play this rough with her... any suggestions?

Seeing as how he is only 4 months old I would say he will grow out of it eventually.

Scold him whenever you see him biting your other dog and either give him a time out in another room or give him a toy.

The time out lets him know that if he bites, he doesn't get to play any more.

The toy will show him that toys are for biting, not cheeks!