A top breeder that I admire had earlier told be that she has successfully combated bsd using white pomeranians. In the process of using whites, she has suffered on quality but the remedy for bsd has been extremely successful.
Now, I have been informed of some white pomeranians have had black skin. So, apparently, the whites are not exempted from this problem but I am inclined to think that bsd is so much watered down in this color because it is quite undeveloped.
I believe that bsd is the result of too much inbreeding and linebreeding. Very much like the human royalties of Europe, hemophilia was the result of their cousin to cousin marriages. Their bastard children(outcross) did not have this problem. I suppose the logic behind this earlier theory is that the whites have less of these in/linebreeding. Ergo, the theory.
Biopsy findings change over time. Initially there is inflammation around the follicle. Over time, the degree of inflammation may lessen, and there is more scar formation. Thus, a biopsy of a late lesion may not yield a specific diagnosis, and sometimes a repeat biopsy of a more active area is required. If the alopecia is “burned out”, or inactive, even multiple biopsies may not help. In such cases, an evaluation by a clinician specializing in hair loss and review of the slides by a dermatopathologist specializing in alopecia may help to correlate the clinical and histologic findings and arrive at a diagnosis. Despite this advanced level of care, sometimes a specific diagnosis cannot be achieved.
DOC's primary purpose is to regulate electrolytes. However, it has other effects, such as to remove potassium from leucocytes  and muscle,  depress glycogen formation  and to stimulate copper containing lysyl oxidase enzyme  and connective tissue,  which attributes may be used by the body to help survive during potassium wasting intestinal diseases.  The greater efficiency of DOC in permitting sodium excretion (or perhaps it should be expressed as inefficiency at retention) must be partly through morphological changes in the kidney cells because escape from DOC's sodium retention takes several days to materialize, and when it does, these cells are much more efficient at unloading sodium if sodium is then added than cells accustomed to a prior low intake. Thus, paradoxically, a low salt intake should be protective against loss of sodium in perspiration.