My feelings when I mention to a vet about some treatment or supplement and they say it probably won't help or work. My next question to them is well will it hurt them? If they say no then I try it anyway!!! If they say yes or don't know then I search out for the answer.
All vets don't know everything!
Think Out of The Box!
Some good videos below.
I would try the Storm's regimen and other recommendations on that site anyway and
@GennyB mentioned.
Storm's Regimen
Since this issue is mostly Genetic in Dobes and some other breeds this can be tough to manage. Not all things will work for each dog. Also Alopecia can be caused by other things like diseases, infections, auto-immune and conditions. So it was good to have the skin biopsy to rule things out.
If the Vet put your Dobe on any antibiotics (which upset the gut bacteria) it's a good idea to give a good a pre and probiotic. Also you might want to keep them on it.
You can also try Biotin and Melatonin has helped in some Dobes we get into the Rescue.
Melatonin Therapy for Canine Alopecia (Hair Loss in Dogs) - Nashville
I know he's only 9mo old. Some things to get checked is to get a Full Thyroid Panel. A dog with Thyroid issues can cause or complicate skin issues. Your vet will probably say he is too young to have Thyroid issues.
Don't know what you are feeding? But a better diet like feeding a raw or home cooked diet can help.
Most kibble foods are very high (40-60%) in Carbs. Starch is used in foods like kibble to hold the kibble together. Starch=Carbs=Sugar. Sugar can feed Yeast.
Some recommendations.
Better diet.
Adding a good (we use Icelandic Pure Amazon $20 for 33oz) Omega 3 Fish Oil. We have been using one made from Sardines, Anchovies or Mackerel.
You can also add canned Sardines (ones that are in water) drain and feed 3-4x's a week.
Keep giving a Pre and Probiotic. These I would give separate (couple of hours before or after) from eating times and giving antibiotics.
Can also give Organic Brag's Apple Cider Vinegar 1Tsp 2x's a day on his food. ACV is antifungal and antibacterial. Can also put (use a cotton ball) on affected areas of the skin.
Adding Organic Coconut Oil to food. Coconut Oil contains Lauric Acid which is antifungal and antivirus. Can also melt some and put some on your hands and rub into affected areas. But also he might want to lick those areas.
There are some medicated shampoos. Also I would only use an Organic shampoo (not with Oatmeal) with a conditioner. Because you don't want to take out the natural oils out of the skin.
Some treatments say to use Oatmeal in them. But if your dog has allergies I would stay away from Oatmeal in the ingredients.
I would limit any vaccines. If he had his core puppy vaccines he most probable not need any boosters. Core vaccines can last 5-7yrs and up to the life of the pet.
A good contact is Atlanta Acupuncture which has lots of supplements and Chinese Herbs that might help.
Pets
About Food Diets
Can try this foot soak for his feet.
Dr. Becker's Holistic Tips for Pet Allergies
Yeast Infection in Dogs
Color Dilution Alopecia in Dogs
What Is Color Dilution Alopecia and How Is It Treated in Dogs?
Alopecia in Dogs
What is Alopecia and Why Does a Dog Get it?