Toxicologic veterinary clinical pathology—how is it different from diagnostic clinical pathology?

Abstract

Veterinary clinical pathology is a board examination specialized discipline in veterinary medicine focused on the study and understanding of animal disease based on measured variables and analytes, predominantly in peripheral blood, but also other body fluids, and their diagnostic significance. In clinical veterinary medicine, clinical pathology has been established as a standard component of the diagnostic process for decades, similar to human clinical medicine. Likewise, the collection of clinical pathology data in laboratory animals is an established standard practice in preclinical studies in drug development. However, non-pathologists such as toxicologists and study directors in the pharmaceutical and agrochemical industries can find it difficult to understand the relevance of the clinical pathology data. This review will outline and discuss certain important differences between diagnostic and toxicologic clinical pathology (TCP) and list some typical examples mainly in hematology and clinical chemistry including some important contextual considerations in addition to treatment-related changes in peripheral blood, such as urine; in-life observations; and histopathology. Most importantly, while in clinical diagnostics, the main question is whether an animal or patient is sick or healthy, and in case of obvious disease, what exactly the animal is suffering from, the question in toxicologic clinical pathology is whether there are treatment-related effects that can be determined based on dose-dependent differences in laboratory data between treated groups and the control group with or without statistical significance and of adverse relevance. As in clinical diagnostics, some very specific preanalytic but also analytic considerations are required for scientifically and toxicologically sound final data analysis, interpretation, and reporting.