Clinical relevance of Veterinary hematology parameters
Hematology is one of the most common diagnostic tests performed worldwide, and it is important to understand the relevance of each parameter. Understanding the origin of the cells, their developmental stages, and factors that can affect the abundance and production is equally important.
When working with veterinary hematology, the variation in cell morphology and behavior between and within different species adds complexity and call for special considerations.
Anemia, for example, is a very common clinical diagnosis that is generally associated with low hemoglobin (HGB), hematocrit (HCT) and red blood cell (RBC) count. To assess the symptoms, set the diagnosis, and determine the cause and prognosis, however, several parameters need to be taken into consideration. For example, the reticulocyte count reflects the regeneration of red blood cells in the circulation and is thus a valuable parameter when investigating anemia in humans. For animals, however, the reticulocyte count varies greatly between and within species, and sometimes even within an individual. Among the anomalies are horses, having no reticulocytes at all, even when suffering from severe anemia; rodents, with a variation in reticulocyte count that ranges from 2% to 90% over the lifetime of an individual; and cats, having two distinct types of reticulocytes that need to be assessed separately to provide sufficient insights for a diagnosis. In other words, the utility of reticulocyte count for anemia investigation in animals is limited and can only be applied for certain species.
Basophil and eosinophil counts are two other hematology parameters, which are readily associated with allergies, parasite infections, and certain forms of cancer. In animals, an increased count of one of them is most often accompanied by an increased count of the other. For several animal species, however, the basophil count is very low (<<1%) and basophilia rare, making eosinophil counts a more versatile and relevant parameter to assess.