When you need to leave your dog in the backyard for long stretches of time, it is important to prevent it from becoming bored. Dogs who become bored tend to become problem-barkers or become listless and lethargic. Give your dog plenty to do when you are gone and it will be much more content and calm.
Measure out a length of rope and hang a tire from a tree. Tire jumps are a common part of agility trials, and dogs enjoy jumping in and out of tires. They can keep themselves entertained by jumping the tire even when you are not around.
Offer your dog a wide variety of toys to play with when you leave it in the backyard. Noise-making toys are more appropriate for outdoor play, rather than indoor play, as the sound will not be annoying to the house's occupants.
Heighten interest in the toys by scenting them with vanilla extract. This keeps the dog interested in them. You may also use anise or even hunting scent to freshen the dog's interest in old toys.
Fill a plastic wading pool for your dog, especially when it is warm outside. A plastic wading pool gives the dog a place to cool off in the hot summer sun.