The dog was glowing in the dark! Jaundice is defined as a yellow discoloration of the sclera, skin and mucous membranes. This is due to the deposition of the pigment bilirubin. Icterus is another term used interchangeably with jaundice. Hyperbilirubinemia, however, is applicable whenever the serum bilirubin exceeds normal.
One of the most common manifestations of hepatobiliary disease is ‘icterus’. The places to look for icterus on physical examination are the
sclera, third eyelid, soft palate, & below the tongue. Icterus can often be visibly detected in the serum before it is visible in tissues. Causes of hyperbilirubinemia are divided into three main categories. Increased production (haemolysis), also termed prehepatic; Hepatic disease causing inadequate uptake, conjugation and/or excretion of bilirubin; and Posthepatic causes (abnormal biliary excretion of bilirubin). Mild elevation of serum bilirubin can also occur with the artifacts of haemolysis/lipemia.
Approximately 10% of all patients with liver disease have clinical jaundice. In cats with hepatic lipidosis, greater than 95% present with hyperbilirubinemia. Conjugated bilirubin in plasma binds irreversibly covalently with albumin (called delta bilirubin), whose half-life is about 2 weeks. Therefore, a patient may remain visibly icteric for several weeks despite resolution of the problem!
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