Lisa Wallis and Friederike Range of the Messerli Research Institute at Vetmeduni Vienna have designed tests to study the effect of aging on cognitive processes such as learning, memory and logical reasoning in dogs. Something that has not be explored previously.
The researchers tested 95 Border Collies that ranged in age from 5 months to 13 years. They picked this breed because of their reputation as fast learners and because as a popular pet, there were enough dogs available for testing.
The dogs were divided into five age groups and tested for learning, logical reasoning and memory. The test involved a touchscreen with images on it. What the researchers found was that older dogs learned more slowly with less flexibility in their thinking. However, logical reasoning increased with age. Also, long-term memory was not affected by age, all of the dogs were retested six months later and all had no problem recalling the positive images.
So, you can teach an old dog new tricks, although it may take longer. As a certified animal behavior consultant, I find that older dogs are more likely to have formed habits that are harder for them to break. If the new trick, or task requires them to change a habit, it may be hard for them to accomplish that, the same as it is for people.