The association between hepatic
lipidosis (HL) and disease in 59
anorectic, ketotic, lactating Holstein heifers and cows was investigated. Severe HL, as determined by histologic evaluation of liver tissue, was present in 46 animals; only half of these animals required intensive treatment for
ketosis, and only half had serum biochemical evidence of
liver disease, as determined by the presence of a last value of 2-fold or greater than the upper limit of the reference ranges for at least 2 of the 4 serum tests: gamma-glutamyl
transferase,
aspartate aminotransferase, and
sorbitol dehydrogenase activities and
bile acid concentrations. Most cattle with biochemical evidence of
liver disease and severe HL had been lactating for 14 or more days. Cows that required intensive treatment inconsistently had serum biochemical evidence of
liver disease. Although cattle with severe HL had significantly higher serum
bilirubin concentrations and
aspartate aminotransferase and
sorbitol dehydrogenase activities than cattle with less severe
lipidosis, the specificity of abnormally high serum
sorbitol dehydrogenase activity or
bilirubin concentration for severe
lipidosis was only 8%. Abnormally high serum
aspartate aminotransferase activity was 83% sensitive and 62% specific for severe
lipidosis. Serum
glucose and total
carbon dioxide concentrations were significantly lower in cattle with severe
lipidosis than in those with mild or moderate
lipidosis, and low serum
glucose or total
carbon dioxide concentrations were rare in cattle without severe
lipidosis. From these data, we conclude that the use of a single biochemical or histopathologic criterion to define severity of disease or degree of liver compromise in
anorectic, ketotic cows results in the misidentification of many animals.