Blood tests are a part of veterinary care known as laboratory medicine (for more information, see What Blood Can Tell You on TheHorse.com). Laboratory medicine is used by your veterinarian–along with physical examination findings–to aid, confirm, or disprove a suspected diagnosis. While the first part of this series discussed hematology (the study of blood), this part will discuss the second-most common laboratory analysis performed–the serum chemistry panel. What does that mean, and how can that information help your horse get well?

A Stable Horse

Remember that blood is approximately 60% water and approximately 40% red and white blood cells, with the rest of "blood" containing hundreds of elements, electrolytes, enzymes, and proteins. When measuring blood's different components, one should remember that each laboratory has its own set of normal ranges, which depend on their individual equipment, geographic population of horses, and many other factors. With serum tests, there are more gray areas of interpretation and a wider degree of variability. Your veterinarian will know which values he considers normal and abnormal for a specific laboratory.

We are now interested in some of the components in the blood's "serum." The serum is the clear-to-yellowish fluid remaining after the blood sample is allowed to clot and has been centrifuged (spun so that the red cells are removed). The serum contains electrolytes, a variety of proteins, enzymes, and many waste products of metabolism