Thanks for the answers to my questions although I'm sorry I was off my computer when you did so.
If Abby were my patient, then I'd want to consider Hypothyroid Disease as a possible explanation for the condition of her coat and loss of energy.
While there could be other possible explanations for her symptoms (a dog's coat can often change if systemic disease is present), I'd probably want to rule out a low thyroid first.
Hypothyroid Disease isn't always the easiest thing to diagnose in a dog but in most patients, the T4 will be low; additional testing is then suggested to help confirm that this might be the problem. Most labs will run this test when chemistries are submitted which can help to evaluate her other organs systems such as kidneys, liver as well as a cbc (complete blood count) to evaluate her red and white cells and platelets so that nothing is missed.
Treatment of Hypothyroid disease is easy and fairly inexpensive although these patients will need to be treated for the remainder of their lives.
If she weren't a little off in terms of her energy and it was just her fur which was the problem, then I might suggest a different diet ...which you could do anyway...but diet is not likely to be responsible for all of her symptoms.
I might also consider adding fish oil to her diet which may help regardless of any other underlying issue although this should improve if she is diagnosed with Hypothyroid Disease and replacement therapy is started. But, Welactin is a good veterinary brand name which is liquid that can be drizzled on the food. It's often available at local pet/grain stores or online.
I hope this helps to provide options for you to consider. Deb