Old Dog, New Tricks by David TaylorThe Mythbusters covered this issue in episode #74 last March.
Ask Yahoo.com tried to dispel the old dog myth in a single webpage.
Veterinarian, David Taylor, on the other hand, wrote a whole book on the subject entitled: Old Dog, New Tricks. The book was thorough on discussing canine behavior and training with the senior adoptee dog in mind.
Taylor covers the basics about training with rewards and tells readers that old dogs will learn if you have lots of patience and the wherewithal to never use punishment because it is ineffective and can do more harm than good. There is a fair amount of information on signs your older dog may be having medical problems instead of behavioral issues. Taylor gives a nice overview of how to handle specific issues like fearful dogs, aggressive dogs (including the different types of aggression), destructive dogs, and our personal non-favorite: house soiling dogs.
All in all, you might get a good deal out of this book if you are about to adopt an older dog or want to understand more about canine behavior.
Click on the image for the Amazon webpage link.