Chronic care and monitoring of woodchucks (Marmota monax) during repeated magnetic resonance imaging of the liver.

We monitored the development of hepatocellular carcinoma due to chronic infection with woodchuck hepatitis virus by using monthly serum samples, physical examination, and magnetic resonance imaging. The same woodchucks can be imaged repeatedly over a 1-y period by allowing the animals to recover after each experiment, thus reducing the number of animals required without compromising the quality of the data obtained. Age- and sex-matched uninfected control (n = 5) and chronically infected (n = 5) woodchucks were group-housed according to sex and infection status.