Handicapped by the limits of radiology, Ultrasonography and physical examination, we rely heavily on clinical pathology for the diagnosis of inflammation and disease in most cetaceans. Over the years we have become more sophisticated in our interpretation of laboratory data; however, we continue to search for new inflammatory markers which display a greater degree of specificity than those in current use.

Traditionally used markers of inflammation are white blood cell count, differential count, hemoglobin concentration, mean cell volume, reticulocyte count, erythrocyte sedimentation rate, serum fibrinogen, serum alkaline phosphatase, serum iron, and serum albumin. These parameters change under most inflammatory disease conditions, however they suffer from being nonspecific.

In species where it has been studied, Interleukin 6 (IL-6) is one of the primary cytokine initiators of acute inflammation. It is present in all cases where there is acute phase inflammation and has an active role in the regulation of the inflammatory response. In a limited number of clinical cases involving cetaceans with inflammatory disease, as evidenced by a change in one or more of the classical inflammatory markers, we have observed levels of IL-6 ranging from 5 to 22,500 U/ml by bioassay, as contrasted with normal animals which have no detectable circulating levels.

The existence of 1L-6, having been cloned and sequenced in cetaceans, provides us a tool to monitor disease in these animals. Since IL-6 is produced early in the inflammatory response one of its unique values, as a diagnostic tool, may lie in the identification of subclinical inflammatory disease not already identified by other clinical markers. In the future, we expect to evaluate its role in chronic disease states and, most importantly, determine whether IL-6 has a prognostic value.