Veterinary necropsy, postmortem change and specimen integrity
Establish the history and permissions
A necropsy begins with the identity, species, age, circumstances of death, clinical history and the actual diagnostic questions. Determine whether a serious infectious or occupational hazard changes the permitted examination and laboratory pathway. An unexplained sudden death does not justify opening every carcass in an ordinary setting. Suspected anthrax and other dangerous conditions require competent advice and suitable containment. Record the source of the history and distinguish observed facts from an owner's interpretation.
Separate disease from change after death
Cooling, rigor, autolysis, blood redistribution and bacterial decomposition evolve under different environmental conditions. One clock time is not a universally reliable estimator of the interval since death. Pseudomelanosis can arise from sulfur compounds reacting with iron, whereas true pigmentation has other causes. A distended bowel at necropsy does not alone prove a fatal antemortem obstruction. Congestion, hemorrhage, inflammation, tissue injury and the relationship between affected and unaffected regions help evaluate whether a process occurred during life.
Examine systematically and preserve relationships
Describe external and internal findings with location, extent, distribution, consistency and relevant measurements. Photographs should include orientation and scale without replacing a written description. Maintain the relationship between an organ lesion and associated vessels, ducts, lymph nodes or adjacent tissues. A complete examination can reveal competing causes or incidental findings. The most dramatic lesion is not automatically the cause of death, and a normal gross appearance does not exclude important microscopic or functional disease.
Plan specimens for several possible investigations
Histology, microbiology, toxicology and molecular tests may require separate containers, temperatures and handling. Choose representative tissue, label it unambiguously and communicate the laboratory question before collection. Formalin preserves morphology but is not appropriate for every culture or chemical analysis. Avoid cross-contamination and retain chain-of-custody information when relevant. Fixation quality depends on tissue access, dimensions, time and appropriate conditions, not one universal volume ratio alone. Report limitations such as decomposition or incomplete sampling explicitly so a negative finding is not mistaken for a comprehensive exclusion of disease.