Adventures of Milo and Otis
A classic 80s movie about a curious cat named Milo, and a blunt-nose pug named Otis, working together on heading back home when Milo got pulled away by the river inside of a box after playing hide and seek, and Otis came to rescue him in a hole. Then they worked their way back home to bring back peace. But then, they choosed to make love with their new mates, Joyce the white female cat, and Sandra the darker pug. Both brides made children, continued working their way back home, and lived happily ever after.
I believe the Adventures of Milo and Otis is better than any other animal movie, but tied with Fly Away Home.