Hepatic disease

A.  Serum bile acids (SBA)

Bile acids are produced in the liver and stored in the gall bladder. Feeding results in gall bladder contraction and release of bile acids into the intestine where the majority undergo enterohepatic circulation. As such, measurement of serum bile acids can be used as an indicator of hepatic function, although increases in serum concentrations are not specific for a particular disease process, or for the severity of disease present. Additionally, diseases such as hyperadrenocorticism, which can secondarily affect the liver, can also result in increased serum concentrations.

Determination of both 12-hour fasting and 2-hour post-prandial serum bile acids is suggested in dogs and cats. Horses lack a gall bladder, therefore a randomly timed sample is adequate. Cows have a wide reference interval for serum bile acids in health, thus decreasing their use for detection of hepatic disease.  

A number of variables may affect serum bile acid results.

Prolonged fasting, intestinal malabsorption, or altered gastrointestinal transit time may lower serum bile acid concentrations and decrease the ability to detect concurrent hepatobiliary disease.

Spontaneous gall bladder contraction may result in a fasting bile acid concentration which exceeds the post-prandial result. Patients receiving ursodeoxycholic acid (Ursodiol) will have falsely increased serum bile acid values because this drug is detected by the method used at the Animal Health Laboratory.

Serum bile acids will be simultaneously increased in patients with clinical icterus or increased serum conjugated bilirubin as a result of interruption of enterohepatic circulation, thus serum bile acid determination does not provide any indication of hepatic function in these circumstances.

B. Hepatic fine needle aspiration

Fine needle aspirate (FNA) of liver can be useful in the diagnosis of generalized hepatic disease, e.g., hepatic lipidosis, lymphoma.