A canine febrile disorder associated with elevated interleukin-6.

Familial Mediterranean Fever (FMF) is a human disorder characterized by recurrent fever of unknown origin (RFUO), renal amyloidosis, and evidence of peritonitis, pleuritis, and/or synovitis. This report suggests that Chinese Shar-pei (CSP) dogs suffer from a similar syndrome. CSP dogs with RFUO (n = 15) showed greater levels of IL-6 in serum than normal controls, hypergammaglobulinemia, and normal or supranormal in vitro lymphocyte blastogenesis in response to mitogen stimulation, when compared to healthy afebrile dogs. In patients 2 years old or older, RFUO was associated with renal failure, renal amyloidosis, and swollen joints. An epidemiological survey of privately owned dogs indicated a RFUO prevalence of 23% in CSP dogs (n = 132) and 1% in dogs of all breeds (n = 98). Increased levels of circulating cytokines, such as IL-6, have been shown to influence such processes as the febrile response, antibody production, and the synthesis of amyloid precursors. We propose that CSP dogs with RFUO, renal amyloidosis, and joint inflammation may serve as an animal model of FMF and that the clinical syndrome is associated with elevated levels of circulating IL-6.