Thin hair like that which is not patchy seems systemic to me so I would get a second opinion from a vet who is like an internest/diagnostician. Thyroid and other genetic disorders that can be hard to diagnose can cause problems like that so possibly another veterinary mind is in order.
__________________  Jeanie and Tibbe One must do the best one can. You may get some marks for a very imperfect answer: you will certainly get none for leaving the question alone. C. S. Lewis |