Serous fat atrophy in forensic veterinary pathology of domestic mammals

Serous fat atrophy is the result of prolonged energy insufficiency and represents an important finding to confirm a diagnosis of emaciation in forensic veterinary pathology. The objective of this study was to investigate the presence of serous fat atrophy at multiple anatomical sites in different mammalian species in order to identify the most suitable sampling locations when emaciation is suspected. In addition, the study evaluated different fixation methods and a panel of histochemical stains to improve the histopathological diagnosis of serous fat atrophy. In all species included, bone marrow was the most reliable site for demonstrating serous fat atrophy, often followed by the adipose tissue surrounding the knee joint. In the carnivorous species, epicardial adipose tissue was limited, yielding a space or an unidentifiable amount of extracellular material. Retrobulbar adipose tissue was also suboptimal for evaluating serous fat atrophy in several species. Fixation in 10% buffered formalin produced stronger metachromatic staining with Toluidine blue compared with Carnoy's solution, indicating superior preservation of glycosaminoglycans in the tissue. While multiple histochemical stains were useful in showing the formation of glycosaminoglycans, the metachromatic stains ease the identification process, making them a preferable option. Therefore, when performing forensic necropsy of an animal suspected of emaciation, bone marrow should be considered the tissue of choice for identification of serous fat atrophy, the tissue should be fixated in 10% buffered formalin and metachromatic stains are recommended for optimal visualization.