I have a 10 month old yellow lab that had demodex so I put him on the Nutro Ultr...
Demodex, also known as Demodectic Mange, is a parasite that lives in the hair follicles and is passed directly from mother to puppy. I recommend consulting your veterinarian to see if your puppy needs topical medication.
Blue Buffalo, Wellness, and Nutro are all good foods. Be careful when changing your dog's diet as new food can cause stomach issues too.
If you have decided to change your pet's diet, feed your pet a combination of the new and old food over a 10-day period to get them used to the new texture and smell. Abrupt changes to a pet's diet can trigger diarrhea and other intestinal upsets, especially if your pet has a sensitive stomach, so be deliberate and consistent in how you do it.
On the first day, feed your pet 90 percent old food, 10 percent new food; continue on the second day with 80 percent old food, 20 percent new food and so on. At the end of the 10-day period, your pet should be fully transitioned to the new food.
As always, consult your veterinarian on the nutritional needs of your pet.