Experimentally induced chronic aflatoxicosis in rabbits
Clark, J.D.; Jain, A.V.; Hatch, R.C.; Mahaffey, E.A.
American Journal of Veterinary Research 41(11): 1841-1845
1980
ISSN/ISBN: 0002-9645 PMID: 7212413 Document Number: 165598
Male New Zealand White rabbits were given (orally) 4 dosage levels of aflatoxin B1 (AFB1): 0.025, 0.0375, 0.05 and 0.0625 mg/kg of body wt daily for 24 days. Feed was available ad lib. Other rabbits were ration-fed without added AFB1, with the following amounts: 10, 20, 40, 80 and 160 g/day. Clinical condition, feed consumption, selected blood values and gross and microscopic pathologic changes were determined. The 2 smaller doses of AFB1 did not produce clinical toxicosis or blood changes. The 2 larger doses produced anorexia, decreased weight gains, lethargy, emaciation, dehydration, icterus and death. Clinicopathologic changes included decreased plasma total protein (TP) and increased blood clotting time, serum bilirubin concentration and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. There were no consistent dose-related changes in serum alkaline phosphatase (ALP) activity and little change in PCV and Hb concentration. Reduced feeding did not affect clotting time, serum bilirubin and AST values. Mean values for PCV, Hb and TP were within usual limits but gradually decreased in animals given 10, 20 and 40 g feed/day. In the latter rabbits, mean serum ALP activity decreased to less than that of control rabbits. Mean serum ALT activity was normal except on day 23 when values were moderately increased in rabbits given 10 and 40 g feed/day. Gross pathologic changes were observed in most rabbits given 0.05 and 0.0625 mg AFB1/kg per day. Icterus of body tissues was apparent and liver of icteric animals was yellow to orange. Traces of fresh blood were found within jejunal lumen. Microscopic changes were observed only in liver and were more consistent and severe in animals given daily dosages of 0.05 and 0.0625 mg AFB1/kg. Histopathologic changes in liver sections from rabbits given 0.025 and 0.0375 mg AFB1/kg dosage included increased cytoplasmic eosinophilia and loss of cytoplasmic granularity of hepatocytes. In livers of some rabbits, a mild increase in the proportion of binucleate hepatocytes and mild karyomegaly were noted. Bile duct hyperplasia was not evident. Liver sections from rabbits given 2 larger dose concentrations of AFB1 had similar but more severe changes in hepatocytes. In addition, bile stasis was found within biliary canaliculi of several rabbits. Portal triads in some liver sections contained many cells with fusiform nuclei and little visible cytoplasm. Hepatic necrosis was not detected in any rabbit. Hyperplasia of biliary ductular epithelium was seen in 1 rabbit.