Evaluation of actin and desmin expression by immunohistochemistry to determine the time since death in dogs

The estimation of the time since death can be of vital importance in a forensic investigation. Several different methods are available to the forensic investigator for estimation of time since death, including temperature- and molecular-based methods, and entomology. The use of immunohistochemical (IHC) methods has rarely been studied for estimation of time since death. To determine whether IHC staining can be used for estimation of time since death in dogs, we selected skeletal muscle as it is abundantly available and slower to decay compared to other tissues. Euthanized dogs (Canis familiaris) were allowed to decompose for up to 30 days in a walk-in refrigeration unit. Thigh muscle tissue was collected from a single dog on postmortem days 0, 2, 4, 6,…, 28, 30. Tissues were formalin-fixed and IHC-stained for muscle-specific actin and desmin. IHC staining was evaluated using the immunoreactive score (IRS) system. Skeletal muscle from all dogs stained positive for the duration of this study. Desmin staining was negative at days 10 and 26. The results show that immunohistochemistry can be performed on dog skeletal muscle for at least 30 days postmortem and support the further investigation of the use of immunohistochemistry for muscle markers to investigate the time since death for periods longer than 30 days.