Systemic lupus erythematosus (SLE) is an autoimmune disease affecting multiple systems and has been reported in humans, dogs, and cats. Although known since the 19th century in humans, SLE was not recognized in the dog until 1965. Since the first case report, a number of cases have been documented in the dog. On the other hand, the firs case of SLE to be suspected in a cat was in 1971, and only five further cases have appeared in the literature.