Post-mortem clinical pathology in cattle - an additional tool for the veterinary pathologist

Clinical-pathologic examination of samples collected from more or less preserved body compartments during necropsy may provide important information and contribute to the list of differential diagnoses without corresponding patho-morphologic findings. It furthermore allows for diagnoses that otherwise may only be achieved clinically. Our review presents diagnostic approaches in examining aqueous humor, urine, ruminal fluid as well as other sample types characterized by a delayed onset of auto- and heterolytic artefacts. An overview is provided concerning post mortem (p. m.) sample types and collection methods with a special focus on cattle. Furthermore, clinical-pathologic methods and parameters are presented and their validity discussed. A summary of pre-analytical caveats relevant for the final interpretation of findings is made available. Based on long-term experience in p. m. clinical pathology as well as literature information we provide practical approaches for daily routine diagnostics as well as for specific case scenarios. Especially aqueous humor, ruminal fluid, and urine are easily accessible sample types. The collection of high-quality cerebrospinal fluid allows for electrolyte and metabolite analyses. Post-mortem clinical pathology may provide an indication concerning the cause of death in specific cases e. g., recumbency and death due to hypocalcemia or hypomagnesemia. This is especially relevant in cases in which ante mortem clinical pathology investigations are hindered by rapid death of the animal as well as in cases in which the gross pathology findings cannot explain the clinical findings. Post-mortem clinical pathology may also be helpful when a clinical examination of the diseased animal is hampered. During necropsy for example uremia and ketosis may be detected based on their characteristic smell; however, the use of clinical chemical analyses allows the verification by an assessment of the metabolites in these cases. Post-mortem clinical pathology may hence help in establishing a diagnosis, narrow down the list of differentials or even reveal relevant differential diagnoses for the first time during the diagnostic process. Our review does not claim to be exhaustive; however, it serves to encourage the pathologist to make use of the so far rarely employed ancillary analyses as well as to promote the collaboration between veterinary and clinical pathologists.