The following case report describes the presentation, diagnostic workup, and treatment of a 9-year-old female spayed Lhasa Apso who presented to the Emergency Service at Cornell University Hospital for Animals with a presumptive diagnosis of systemic lupus erythematosus (SLE) from the referring veterinarian. Definitive diagnosis of SLE is often complicated given the many clinical manifestations of the disease. A discussion of the diagnostic procedures, diagnostic criteria, as well as the theoretical pathogenesis of the disease, follows. Canine SLE is the animal model for the more common disorder of human SLE. Therefore, though the disease is not very prevalent in the canine population, it is an area of intense research.