Taking Chop for a walk and playing with him is part of the 100% completion of the game. This is one task you won't have any problems achieving. Who can ignore Chop? After completing Lamar's mission "Chop", Lamar leaves Chop in your care.

A doghouse appears behind your safe-house. Chop's current location is shown by a bone icon. This is where you can find Chop. He also moves to the exterior lower floor of Franklin's second safe house in the hills. This is at the bottom of the stairs near the pool.

Without purchasing the Chop app, you can walk Chop and have him ride along with you in vehicles. While being walked by Franklin, Chop will not ride in helicopters, planes, or boats. Also, Chop will not swim. If you try to enter a building with Chop in your care, he is automatically dismissed and runs home. If you get into a bad enough accident while Chop is riding with you, he may jump out of the car when it stops and go home.

When Chop is with you, he attacks anyone that shows aggression towards Franklin, and may even kill them.
To play fetch with Chop, have him follow you and then select the ball from your weapon wheel. You can find it by scrolling through the projectile slot. Throw the ball as you would any projectile and Chop takes off running for it. If he can find the ball, he retrieves it and drops it at your feet. Walk over the ball to pick it up again. Be sure not to put Chop in any danger when throwing the ball (avoid throwing it into heavy traffic).

The Chop the Dog app (part of the iFruit application) can be downloaded for your personal smartphone device or tablet. This allows you to modify Chop's behavior and teach him tricks.

When you purchase the Chop app, a whole new partnership begins. With the app, you can make Chop sit, beg, and you can shake his paw. You can also pet Chop to reward him. One of the most useful Chop commands allows him to find nearby collectibles for Franklin. When near a Spaceship Part or Letter Scrap, Chop starts barking, and does so more frequently as he gets closer.

If you set him loose and command him to hunt for pick-ups, he runs directly to the nearby hidden collectible. If you lose sight of him, follow the bone icon (Chop's blip on the radar and map). You'll find Chop sitting at the location of the nearby collectible. If there are no collectibles in the area when this command is given, a message is displayed explaining there are no pick-ups in range.

This game offers many other interactive options that can be enjoyed by anyone at any age, the guide that helped me is here: http://playstationgameplay.com/