Dear friend,
I think you are referring to Capstar as the oral pill to kill fleas - is that correct?
Yorkies have very sensitive skin. In addition, stress can cause cortesol to enter the bloodstream and interact with the histamine that is already being produced by an allergic reaction. It is also possible the dermatitis can turn bacterial. Frequent shampooing can actually make this reaction worse by leaving a resudue on the skin.
Use a natural, low lather, low irritant shampoo, wet your dog down thoroughly with lukewarm water, and apply the shampoo using your hands. Avoid getting water or shampoo in his eyes and ears, and lather all over, right down to his skin, then rinse thoroughly. Shampoo residue is a major cause of skin irritation for dogs. After rinsing, towel dry your dog, and avoid using any coat finishers or blow dryers, which can also cause skin irritation in a sensitive dog. I would also try an oatmeal shampoo which is very soothing. You can find it in a pet supply or:
www.onlynaturalpetstore.com
www.revivalanimal.com
www.allergicpet.com
If you cannot resolve it with these maeasures, it is likely to be bacteria and will respond to an antibiotic. In sever cases a steroid is employed to reduce swelling or an antihistamine like bendryl at 0.5 to 1 mg of body weight but try the lowest dose first.
Please let me know how he is doing and if you still have any questions. I am happy to help in any way possible.
Very sincerely,
Terri