Balls and rope toys for your dogs should be made specifically for dogs. There is a big difference, and they're much safer for your dog.
Things to consider: how balls and rope are made, keeping your dog interested in her toys, and maintaining proper control.
Made For Dogs - Balls and ropes made for human play are not dog toys. There are chemicals in regular tennis balls and ropes used for utilitarian purposes. Dog balls do not contain the same toxic chemicals regular tennis balls do, and are much safer for your dog should he try to tear it apart or eat off the fuzz. The same goes for rope toys. Often ropes designed as dog toys are made with doggie dental floss, sometimes even infused with mint or other dog dental care aid. There is a reason dog toys are made and sold separately from toys for humans (and despite what cynics may say - it is not all about marketing).
Add Variety - To keep your dog interested in his dog toys, change them often. Vary the types of dog toys, too - balls and ropes, latex and vinyl, Kong, plush and fleece. The pleasant surprise of the constant change and variety in his dog toys -- color, shape, material, texture, scent, taste -- will keep him interested and engaged in playing with them even longer.
Keep Control - Tug-of-War and Catch are two favorite games for dog owners and dogs alike. But if you get the dog in the habit of playing Tug-of-War with any old objects -- socks, shoes, tie-lines for tents, etc. -- or if you play Catch with any old ball -- rubber ball, softball, rolled up sock, wiffle-ball, he'll naturally start thinking that these things belong to him, that they are his toys. To keep your dog from claiming everything you own as his own, only play games with your dog with actual dog toys. Let him know that your balls and ropes are yours not his. In addition, give him his own specially-made dog balls and ropes.
