When looking for a shampoo for your shepherd, you want to find one that has several qualities — the first being that it is formulated for dogs. Dogs have a different pH than humans, so using a human shampoo on a dog can be detrimental to your shepherd's skin. The last thing you want to do is cause an itchy, irritating, uncomfortable condition for your dog.
The shampoo should also be tearless. What this means is that if the shampoo gets in your shepherd's eyes (and it probably will), the shampoo will not cause any burning or serious discomfort. This is not to say that getting tearless shampoo in the eyes isn't uncomfortable — it is, but it's not harmful.
When faced with a full display of different dog shampoos, consider selecting one that is designed for dogs with sensitive skin. Many shepherds have skin allergies or other conditions that can be worsened by a shampoo that is too harsh. By using a shampoo that has been formulated to soothe itchy, sensitive skin, you won't accidentally exacerbate a pre-existing condition. Besides, if your shepherd's skin is healthy, using a gentle, soothing shampoo will not harm your dog in any way.