Acute phase proteins in sheep and goats – function, reference ranges and assessment methods: An overview

Acute phase response (APR) is activated by disorders in systemic homeostasis. The main purpose of APR is to prevent further tissue damage by isolation and destruction of causative agent, removing the toxic products and providing conditions for tissue repair. Probably the most significant change during APR is a transformation in the liver protein spectrum expressed by increased rate of synthesis of acute phase proteins (APPs) or acute phase reactants. Numerous APPs that perform specific functions are established whose quantitative variations vary considerably among different animals. Some of them are mediators (C-reactive protein, fibrinogen), others act as inhibitors (protease inhibitors – α1-antitrypsin) and especially in small ruminants, the most specific APPs are scavengers and transporters (haptoglobin, serum amyloid A). Despite considerable progress, many of the characteristics of APPs in domestic animals are still poorly understood especially in sheep and goats. Little is known about some other proteins such as lipopolysaccharide binding protein, hemopexin, alpha-1 antitrypsin, lactoferrin, transferrin, C-reactive protein, ceruloplasmin, fibrinogen and alpha-1 acid glycoprotein. The aim of this study is to present information concerning the most important functions of APPs, as well as their ranges in healthy sheep and goats and laboratory assay methods.