I agree with Carol and David, to wait for the test results, so you can make a more I formed decision on how to treat him.
I don't necessarily agree with your vet regarding not giving Salo preventative or natural supplements and treats, as yogurt, ACV, salmon oil, cranberry pills, Chondroitin, and fruits and vegetables are all natural and certainly will not hurt him, most supplements that are safe and healthy for humans are also safe for our dogs, and can prevent so many ailments and diseases. I have done a lot of reading and research regarding dog foods, nutrition, and vets, and I have found that just like our medical doctors, their education is spent mostly learning about diagnosing, preventing, and treating diseases, and not very much time is spent on Nutrition, they only study a small chapter on this subject, so don't really know that much about food and nutrition. I also found out that the foods the vets sell in their offices are provided by the pet food companies, and the vets receive a kickback for selling and promoting these dog foods. The breeder I bought my 2 EB from, was feeding them Royal Canin, and he gave me two containers full of this brand along with some toys, and coupons for $ off the food, it was provided by the dog food company. I asked him if it was a good food, and he assured me it was a high quality food. When I asked my vet the same question she told me it was an excellent food, and she sells Royal Canin food in her office. I still wasn't happy with the food, due to the fillers and Corn, in the ingredients, and when I researched dog foods, that is when I found EBN and the dog food ratings, and found theat Royal Canin is rated a 3 star food, and isn't considered very good. Blossom ended up being sensitive or allergic to chicken, salmon, corn and grains, she was having diarrhea, pink skin, pink warm ears, chin rash, itchy, and licking her paws. I switched her food 4 times before trying Fromm's Beef Frittata, and they have been on this food for 14 months, and are both doing well on it.