Inflammatory and oxidative status in European captive black rhinoceroses: a link with Iron Overload Disorder?

Abstract

AbstractIron Overload Disorder (IOD) is a syndrome developed by captive browsing rhinoceroses like black rhinoceroses (Diceros bicornis) in which hemosiderosis settles in vital organs while free iron accumulates in the body, potentially predisposing to various secondary diseases. Captive grazing species like white rhinoceroses (Ceratotherium simum) do not seem to be affected. The pro-oxidant and pro-inflammatory properties of iron, associated with the poor antioxidant capacities of black rhinoceroses, could enhance high levels of inflammation and oxidative stress leading to rapid ageing and promoting diseases. In this prospective study, 15 black (BR) and 29 white rhinoceroses (WR) originating from 22 European zoos were blood-sampled and compared for their iron status (serum iron), liver/muscle biochemical parameters (AST, GGT, cholesterol), inflammatory status (total proteins, protein electrophoresis) and oxidative stress markers (SOD, GPX, dROMs). Results showed higher serum iron and liver enzyme levels in black rhinoceroses (P<0.01), as well as higher GPX (P<0.05) and dROM (P<0.01) levels. The albumin/globulin ratio was lower in black rhinoceroses (P<0.05) due to higher α2-globulin levels (P<0.001). The present study suggests a higher inflammatory and oxidative profile in captive BR than in WR, possibly in relation to iron status. This could be either a consequence or a cause of iron accumulation, potentially explaining rapid ageing and various diseases. Further investigations are needed to assess the prognostic value of the inflammatory and oxidative markers in captive black rhinoceroses, particularly for evaluating the impact of reduced-iron and antioxidant-supplemented diets.