Anything with a lot of Omega 3 fatty acids will improve a dog's coat and many veterinarians recommend using this in cases of dandruff or itchy coats. Bacon grease is an excellent source of both Omega 3 and 6 fatty acids... but comes with potentially fatal levels of fat, as you found out. A good replacement is fish oil which you can buy in either liquid or capsule form.
When I worked for a veterinarian, he always recommended
Lipiderm Healthy Skin and Coat Capsules which can be purchased at your local PETsMART.
Hope your dog recovers quickly!