Chain link fences don't have the reputation of being the best choice for dogs. They're easy to push off the posts (allowing dogs to escape), the edges can get a bit sharp, and they're fairly easy to dig under. But if all you have is a chain link fence and you really need to keep your dog contained, there are a few things you can do to make it better suited to your dog's needs. 

Put caps along the bottom edges of the fence.

You need to prevent the bottom edges of the fence from scraping your dog should he decide to chew on the fence or push under it. Visit your local home improvement store, and purchase some rubberized caps for the bottom of the fence. These usually come in large packages, so you'll have plenty to cap off each piece of wire along the length of the fence. Even if a particular piece of wire does not feel sharp, cap it – it could poke a dog in the eye, and it will cause less damage if it's covered in a smooth rubber cap.

Tie the fence to the posts with some extra wire.

This step is especially important if the fence is attached to the outside of the posts, relative to your yard. You don't want your dog to push against the fence and pop the linked metal off the posts. Take some thick, sturdy wire, and wind it around each post, running it between the chain links as you go. Make sure you tuck the ends of the wires into the fence and cap them with the rubber caps you used on the bottom of the fence so they don't poke your dog.   

Pour gravel along the base of the fence.

A medium-sized dog can dig through gravel, but it will take a lot longer than digging through soil. If you pour gravel in a line at the base of the fence, you'll make it harder for your dog to dig out. You'll at least have time to catch your dog in the act (and fill the hole back in) before he escapes. The bigger the gravel you get, the better – it will be harder for your dog to move it aside.

If you need help repairing or modifying your fence to make it more suitable for your dog, talk to a fencing contractor in your area.