Post-mortem measurements were made of the body temperature of dogs. The aim of the study was to evaluate and verify a reliable mathematical model that can be used to establish the time elapsed since the death of a dog during the initial post-mortem period at room temperature, using the eye (vitreous body), internal organs (heart, liver, kidney and lung), and rectum as sites for temperature measurement. The measurements were performed at six points in the body using an electronic thermometer in conjunction with a temperature probe. The method of temperature measurement is simple and does not cause perceptible macroscopic changes or disfigure the carcass. Multiple regression analysis was shown to be suitable for estimating the time elapsed from death to the discovery of the body for a period up to 12 h post-mortem. The proposed multiple regression equation using body weight and the temperature at a specific site reduces manipulation of the carcass to a minimum and thus reduces error in establishing the time of death. The multiple regression model makes it possible to precisely estimate the time elapsed since the death of the animal.