The effect of environmental storage conditions on bone marrow fat determination in three species

Diagnostic laboratories are frequently required to assess the antemortem nutritional condition of deceased animals. The percentage of fat in the bone marrow is used to diagnose starvation because this fat depot is typically the last in the body to be depleted. Diagnosticians rely on measurement of bone marrow adipose content using fat solvent-extraction methods; however, the effects of tissue storage conditions before processing have not been fully assessed. The current study focuses on evaluating the effects of 3 storage conditions (refrigeration [4 °C], freezing [-20 °C], and ambient temperature [9.9-34.4 °C]) on the percentage of fat in the bone marrow from 3 species. Equine, bovine, and canine humeri and femurs were removed within 24 hr of death from adult animals in adequate body condition and then stored as described for a minimum of 30-60 days. Bone marrow was harvested from these tissues at the time of necropsy and after 30-60 days. Percentage of fat was measured using an automated solvent extractor. Mean percentage of fat in the bone marrow in initial equine, bovine, and canine samples was 81.75%, 86.33%, and 59.96%, respectively. The results indicate that bovine and equine percentage of fat in bone marrow does not change after 30-60 days, regardless of the storage condition, whereas the fat content from canine tissues varies when stored at ambient temperatures. Results suggest that postmortem interval and environmental conditions of samples must be considered in the postmortem evaluation of bone marrow fat concentration in at least some species.