Dermatomyositis (DM) is a skin disease that is most common in the Collie and Shetland Sheepdog. Symptoms of DM vary from dog to dog, with some cases being so severe that euthanasia is necessary. Onset of symptoms may not occur until adulthood and there are no means for breeders to identify affected dogs prior this point. We propose to collect DNA from affected Collies and family members for use in linkage studies. Our goal is to identify a marker, or markers, that can be used by breeders to identify dogs that are predisposed to develop DM. We also aim to identify the gene(s) that may be causative for DM.