Synovial fluid from an African spur-thighed tortoise (Geochelone sulcata).

A 4.5-year old, male African spur-thighed tortoise (Geochelone sulcata) was presented to the University of Florida Veterinary Teaching Hospital with a 2-week history of lethargy, anorexia, constipation, dyspnea, and coughing up fluid or vomiting. Laboratory results included an inflammatory leukogram and a marked increase in plasma uric acid concentration. Synovial fluid from multiple joints was thick, chalky white, and opaque, with a grainy consistency. Microscopically, the fluid contained numerous brown, needle-like crystals consistent with urates (gout). Gross necropsy findings and histopathology confirmed a diagnosis of systemic gout, with urate deposition, gout tophi, and underlying necrosis in multiple organs, including kidneys, lung, and liver. Dehydration with concurrent renal insufficiency may have impaired urate excretion and led to a build-up of urates in the blood and tissues of this tortoise. A high protein diet also may have contributed to the development of gout. Cytologic evaluation of synovial fluid can be used as a quick and definitive tool to diagnose gout in tortoises.