The ONLY thing Dr. Dunbar would do differently with adult animals would be to not start with a mass play session with all animals off at once. Same methods are used on - Whales, Bears, Heyenas, etc. Also, you may well lose the Bond with the animal if you use Negative training methods. Again, watch for changes and do not let thing slip backwards. No such thing.
Animals do things for their reasons.
Training never ends. Re-enforcement is a life long process.