In addition to the local inflammatory reaction associated with tissue injury and infection, a number of systemic responses occur consistently. Mediating most of these responses is interleukin-1 (IL-1). Once IL-1 is released into circulation one of the most dramatic effects is the induction of hepatocytes to synthesize a number of proteins, collectively known as "the acute phase proteins". IL-1 regulates the synthesis of these proteins by altering the rate of protein specific mRNA transcription. While the direct measure of IL-1 is both difficult and expensive, measuring changes in the concentration of acute phase proteins is both easy and inexpensive.

We reasoned that because IL-1 induces an acute hypoferremia by increasing the concentration of serum lactoferrin and ferritin, as well as to decrease the release of iron from the reticuloendothelial system that serum iron concentration might be a sensitive indicator of inflammation and infection in dolphins. Furthermore, there is overwhelming evidence to support the benefit of hypoferremia in reducing bacterial growth and modulating host defense systems.

Serum iron concentrations were determined in wild and captive dolphins and related to clinical, hematologic, biochemical, and pathologic findings. Analysis of the results allowed the examined animals to be partitioned into three groups 1) normal, 2) mild hypoferremia, and 3) severe hypoferremia. Healthy dolphins consistently had serum iron levels in the normal range. Mild hypoferremia was associated with chronic infections, handling stress, and bruising. Severe hypoferremia was found to be a sensitive and rapid indicator of recent severe tissue damage, acute infection, and clinical disease. In addition, repeated measure of serum iron concentrations proved to be a valuable method of evaluating the disease course, prognosis, and response to therapy.

Our findings indicate that routine measure of serum iron concentration is of value in the medical management of captive dolphins, and in the rapid health assessment of wild and recently captured animals. The technique is rapid, easy to perform, inexpensive, and requires a minimal amount of serum.