Spondyloarthritis in Taihangshan Macaques (Macaca mulatta tcheliensis)

The rhesus macaque (Macaca mulatta) is the most widely distributed nonhuman primate species, and captive populations play an important role in biomedical research due to close phylogenetic and physiological similarity to human beings. However, to our best knowledge, the spondyloarthritis (SpA) in rhesus macaques has been exclusively reported in captive or semicaptive populations rather than wild counterparts. In the present study, we report 2 cases of SpA observed in Taihangshan macaques (Macaca mulatta tcheliensis) inhabiting the Taihangshan Macaque National Nature Reserve, Henan Province, China. Among these 2 cases, one can be diagnosed as ankylosing spondylitis (AS) following accepted medical criteria, and another case showed evident fusion at the pubic symphysis which could be specific to rhesus macaque AS. We discuss the potential causes leading directly or indirectly to the development of SpA.