New mini-doxie member here

Hello all, my name is David, I'm new to this forum. I adopted a miniature blue dachshund about a year ago. WHAT AN AMAZING DOG HE IS!!! He was a stud at a puppy farm (puppy mill?) but his sperm count was low so he was put up for adoption. He was only at the rescue place for 10 minutes when I found him, and adopted him on the spot!
My only issue with him is that in the past 6 months, he has started losing his fur. I have tried changing his diet, I've added coconut oil to his food, and I give him 2 fish oil pills in cheese every morning, but nothing has helped. I took him to the vet, and he said that because the blue color is a genetic abnormality, they are prone to losing fur. Does anyone have a suggestion as to what I can do to improve the quality of his fur?
Thanks to everyone, I'm glad to have joined the forum!