German Shepherds are strong, agile and intelligent. Those attributes create special needs when you’ve made the decision to train your dog.
A collar is fine for ordinary walking. But during training, a chest harness will work out better for both dog and trainer. They’re made of leather or very strong nylon with either metal or composite plastic buckles. They fit around the chest, over the shoulders and under the front legs and they’re adjustable.
That makes it possible to fit the harness to be comfortable but also slip proof. A dog in attack mode is going to strain at a leash to the point that even a dog’s strong neck provides inadequate protection against harm, not to mention being tough on your hand. A chest harness is safer for the dog and makes it much easier for the owner to exert control.
Because German Shepherds can be very mouthy, it’s sometimes necessary to strap on a muzzle. It’s not common, but those incidents which have resulted in bites help fuel the German shepherd’s unwarranted reputation for being aggressive. In public areas, where the not-yet-fully-trained dog may be nervous or prone to bite, a muzzle protects others from bites and you from lawsuits.
Muzzles can be leather or nylon, and there are styles that still allow the dog to open its mouth part way. That provides the ability to drink without removing the muzzle, while preventing the dog’s jaws from opening wide enough to look threatening.
Like other breeds, German Shepherds enjoy chewing. A good rawhide bone is a start. But provide these intelligent animals with lots of variety to allow them to practice while they play. Dental-bones are good for health, but provide balls with peanut butter in the center or other ‘puzzles’ to keep them mentally sharp, too.