Hi there,
First thing to mention, because I tend to forget it myself: if you've tried a lot of therapies and/or the dog is on a 'clean' meat and vegetable diet, yet you've seen no success, remember to try elimination diets to identify possible food allergies. These are rare, I believe, but need to be kept in mind when treatments fail.
Regarding this case, I see something you can try first. Here's my analysis:
- Involvement of the sides and dorsum, as opposed to the abdomen, implies a Heat pathogen invasion, and a need to boost peripheral circulation. So using acute acting formulas like Si Miao San is less indicated
- Blood stasis is suggested by the nature of the lesions, as well as the furunculosis on pressure points, which are classic for the condition in that they are focal and persistent
- Heart Fire is implied by the craziness on pred and the cystitis
- Blood and Yin deficiency is implied by the lack of tongue coating and dry hair coat
- The GI signs in response to essential fatty acids implies a Dampness drying and Heat clearing effect is needed, even as circulation is enhanced, and Blood and Yin are tonified
There's only one formula I know of that fits those criteria: Qing Ying Tang. I'd start with it.
One final thing you can do - some sort of topical astringent for the feet. Look for preparations that contain Horse Chestnut or Witch Hazel in health food stores. You'll find them in the sections with products for hemorrhoids or varicose veins. Use per the product instructions
Hope that helps you out
Steve