The next time you look at your older dog snoozing away and wish for those vibrant puppy days, think about brain training.

That's right, think Sudoku for dogs.

Researchers at Messerli Research Institute in Vienna have found that simple computer tasks – with a treat, of course – will help keep aging dogs mentally fit.

As dogs age, their physical limitations may keep them from the games and training they enjoyed when they were younger. But their couch potato status doesn't keep them socialized or challenged, researchers pointed out.

"This restricts the opportunities to create positive mental experiences for the animals, which remain capable of learning even in old age," said Lisa Wallis, lead author of the study.

The team used computer-based brain teasers to test the dogs. It took time to get the dogs used to touch screens, but once they mastered the task, they turned into "avid computer gamers," according to the study.

"The prospect of a reward is an important factor to motivate the animals to do something new or challenging." said Ludwig Huber, one of the senior authors.

What remained unclear from the study was whether it was aging that contributed to the dogs' forgetting what they had learned as puppies or just lack of training.

While the study proves that you can teach an old dog new tricks, Carlo Siracusa, an assistant professor of clinical animal behavior at the University of Pennsylvania School of Veterinary Medicine, said he believes the benefit the canines get from the computer games could also be from more interaction with people.

Dogs are social and are more interested in playing with an individual than with objects, he said.

With older dogs, owners need to be aware of their pets' limitations.

Changes in eyesight, hearing loss, or arthritis might make some things difficult or leave a dog in pain, Siracusa said. If they have visual or hearing problems, owners should use a tap on the shoulder or vibration of some kind instead of a visual cue when getting them to do tricks. Dogs with hip dysplasia might resist sitting not because they are stubborn but because it is uncomfortable, while a long walk with a dog that has arthritis might be painful, he said.

Siracusa also noted that a dog suffering cognitive decline from dementia might not respond normally to stimuli.

Dogs don't need to be stimulated all the time, he said. Scheduling three to four short interactions a day or just being near the dog should be enough. It is the consistency and appropriate exercise that are more important than the intensity.

Just as important as keeping the brain healthy is paying attention to dogs' diets as they age, Siracusa said. There are over-the-counter and prescription diets available for senior animals; owners should consult with a veterinarian to find out what is best, he said.

But unlike humans who derive pleasure from puzzles or Sudoku, the screen games for dogs are more about getting the treat, Siracusa said.

And cats, he said, are a different animal.

Cats are attracted to games that use movement and mimic a ritualized form of predatory behavior – such as laser pointers. But they, too, might lose interest if they don't get a treat, he said.

"Most cats are fine without interactions," Siracusa said.