I had a cat who lost most of her hair twice. (You think I would have learned the first time) Anyway she has her hair back and has regained her health. I found a site called Pet Medicine Chest (not affiliated except a customer). They have several products that helped my cat regain her hair. Hemotox and Metalox and Pro Bac . Hemotox cleans the liver and Metalox removes the heavy metals (yes our pets have them too) the Pro Bac is a probiotic. They are not cheap but alot cheaper than the 2 years I spent carrying Sasha back and forth from the vet who could not help her in the end. Not to mention how my heart would hurt to look at her, she was completely bald from the waist back, not a scrap of hair and the rest was going so I was desperate.
In fact I would not be here if not for Sasha's hair loss. I kept watching her get better, more social, hair growing, going outside again instead of laying around all the time half dead and I figured if cleaning her blood and liver helped her then it might help me.
Since then I have put all my pets on their products, the dogs used to get ear infections at least once or twice a year. (That would usually cost about 130 bucks per incident for 4 dogs. They have not had any for the last 2 years since putting them on the regime from Pet Medicine Chest. All their products are top quality and organic. I take some of the products too, especially the probiotic. The have a product called parastem for parasites which is effective against heart worms.
Good Luck with your dog
PS This cat will only dry cat food and is doing fine. Most of my pets are on real food diets but Sasha won't eat anything but Purina One. She does get the Pet Medicine Chest Vitamins, Worm Powder and Pro Back dailey on the dry food. I have to do a cleanse for her several times a year with the other products. They also have a colon cleansing fiber product which I give the dogs but Sasha won't take it.