I'm assuming it's hair loss consistent throughout body, so not caused by pests, low thyroid, hormone imbalance etc. I would give flaxseed oil or ground flaxseed daily as well as a teaspoonful of coconut oil 3 x a week. Also, brush dog daily with a furminator and Zoomgroom brush. Try to eliminate allergies such as food and environmental allergies by switching dog foods, cleaners if needed. If your dog does have environmental allergies you should give him an antihistamine such as cetirizine daily. If he has a yeasty smell you might want to wash him twice weekly for a few weeks with Curaseb or Malaseb shampoo (while brushing with a Zoomgroom brush) and then weekly. This will get rid of the yeast and the fur that's shedding at the same time.