Transthyretin (TTR), also known as thyroxin-binding prealbumin, is a serum protein with a molecular mass of 55 kDa made up of four identical subunits. The prealbumin name is derived from its mobility during electrophoresis as it migrates faster than albumin. It is one of the three major thyroxine binding proteins and forms a complex with retinol binding protein to aid the transport of vitamin A in plasma. TTR is a negative acute phase reactant and serum levels fall due to decreased synthesis in inflammation, malignancy and protein wasting diseases of the gut or kidney. Human serum levels of TTR are measured in diagnostic laboratories as an indicator of health status and a number of commercial assays are available for this purpose. However, such tests have yet to be established for the pig. The aim of this study was to develop an assay to measure TTR in porcine serum.