Do read the labels, making sure that there are no artificial fragrances or colors added to the shampoo. Your dog may be a big strong guy and still have sensitive skin. Look for natural skin moisturizers like vitamin E, aloe vera, honey, and tea tree oil. Fragrances to look for should be natural; chamomile, lavender, eucalyptus, and citrus are some examples of clean, pleasant fragrances, some of which also do double duty as insect repellents. If you can find organic or natural dog shampoos , even better, but don't rely on the front label alone. Again, read the ingredients list.