Dermatomyositis is a familial disease of blood vessels (vasculitis) that is seen in Collies, Shelties and some other breeds especially the Jack Russell Terrier.
Typically it has a long course of repeated skin death and scarring. Tail tips, ears and extremities may also be involved. Sunlight makes it worse. Responds well to immuno-modulating treatment
Yarrambat Vet Hosp03 94361399