A TECHNIQUE FOR SERIAL LIVER BIOPSIES IN THE WOODCHUCK (MARMOTA-MONAX)

In a long-term study on the additional effect of aflatoxin B-1 on wood chucks (Marmota monax) experimentally infected with woodchuck hepatiti s virus (WHV) sequential individual biopsy samples of the liver were n eeded for cytomorphological, cytochemical and molecular genetic analys is of hepatocarcinogenesis including the virological status. Standard biopsy techniques were inadaptable to the woodchuck and to the specifi c requirements of the study. We performed surgical biopsies by cutting the edge of one liver lobe after placement of overlapping horizontal mattress ligatures to secure hemostasis. With the technique described here 107 operations were performed with a mortality of 1.9%. 33 woodch ucks were operated twice, 31 of them with an interval of 12 months (sp ring - spring) and 2 with an interval of 6 months between the operatio ns. Another 13 animals were operated 3 times with intervals of 6 month s (spring - autumn - spring). In general there were no serious intra- or postoperative complications. Local antibiotic treatment was necessa ry to prevent wound infections. After the first and second operation a ll animals had adhesions and fusions of the liver and the greater omen tum with the abdominal wall so that it was not possible to take liver tissue in 10 out of 107 operations. In 97 operations samples of the li ver with a size of approximately 2.0 cmx0.5 cmx0.3 cm were taken. The time from induction of anaesthezia to freezing of the samples was 40 m inutes on an average. The specimens were of sufficient quantity and qu ality for histomorphological, histochemical, molecular genetic and vir ological examinations. Woodchucks are hibernators and their endogenous circannual cycles persist even under laboratory conditions. Seasonal metabolic changes led to reduced tolerance to anaesthestics and prolon ged wound healing in autumn. Thus, for a detailed serial monitoring of hepatocarcinogenesis it is advisable to perform liver biopsies in spr ing only and to replace them by ultrasound imaging and plasma biochemi stry in autumn.