Jaundice, or icterus, is an increase of biliary salts in the blood that takes one of three forms. Pre-hepatic jaundice, or hemolytic icterus, occurs due to massive blood destruction that overwhelms the detoxifying capacity of the liver.
Hepatocellular icterus comes from direct liver injury, and post-hepatic icterus is caused by obstruction of biliary drainage.
The main symptom is yellow colouration of white connective tissue in the body, skin or eye sclera, the latter being the only sign in pigs.
Several infections can affect directly the blood or the liver: Leptospira (mainly fetuses), mycoplasma, E. coli and Salmonella. In all cases other signs can help to address infective causes. Ascaris suum can also cause icterus through direct parasitosis of the liver with later migration to the lungs. At the abattoir white spots are evident in the liver.
Toxicoses such as copper excess and mycotoxins that primarily target the liver can lead to jaundice, particularly when aflatoxin and fumonisin concentrations reach high levels in feed.