Estimation of the post-mortem interval in beagle dogs
Introduction
Estimation of the post-mortem period contributes to the investigation of death by narrowing the “window of time” during which death may have occurred. The more precise the estimate, the greater are the possibilities of eliminating specific people or events from the investigation. In a veterinary context, these investigations may involve incidents of out-of-season shooting of game animals, poaching, deaths of animals during transportation and cases of neglect or deliberate abuse of companion animals. Similarly, determination of the time of death may be crucial where several animals are found and the question arises of whether this was a single episode or an ongoing problem. Accurate estimation of the time of death is also important in cases where alleged offences are related to statutory time limits regulating, for example, the checking of traps and snares or disposal of carcasses.
In human forensic medicine, study of the time of death is one of the most popular topics for research [1]. However, in the veterinary medical field there is a paucity of published data on estimation of the post-mortem interval. Limited information is available on certain species of deer and other wildlife [2], [3] but studies on companion animals and domestic livestock are lacking.
Veterinary pathologists rely on their experience of autolysis and putrefaction to estimate the time that has elapsed since death. The diversity of animals and the variety of circumstances in which they are found renders these judgements very subjective. James and Knight [4] point out in their article “Errors in estimating time since death” that experienced forensic pathologists frequently underestimate the post-mortem interval. Although no similar data have been published on the subject of veterinary pathology, it is probable that, given the range of species covered and the variety of circumstances, similar errors may be commonplace.
In an attempt to provide objective criteria for the measurement of the post-mortem period in dogs, the current study was conducted on dogs of the same breed, similar weights and held under identical conditions. This study complements published texts on post-mortem changes in domestic animals [5], [6], [7] by highlighting specific gross and histological changes that may assist in refining the estimation of the time of death.
Section snippets
Materials and methods
The dogs included in this study were laboratory beagles from a large breeding facility. They were either ‘retired breeders’ or fell outwith the requirements for use in regulatory scientific procedures. After thorough assessment and ethical review, it was decided that they were suitable for this study. Six females and four males with a median weight of 12.1 kg were grouped in pairs of similar weight and same sex. Following euthanasia with pentobarbital sodium the dogs were placed in lateral
Temperature
Ambient temperature in the storage room varied from a minimum of 10.9 °C to a maximum of 16.8 °C. Humidity ranged from 34% to 63%.
The rectal temperatures of all ten dogs are shown in Table 2. By 17–17.5 h after death the rectal temperature of each dog was less than 19 °C. Fig. 1 shows, in the form of ‘box and whisker’ plots, the fall in rectal temperature over the first 13 h post-mortem for dogs 1A, 1B, 2A, 2B, 4A and 4B. The rectal temperatures of all ten dogs approximated ambient temperature
Discussion
A number of factors in the study design influence the interpretation of the data. Standardisation was introduced by ensuring that all the dogs were of the same breed and of similar weights. They were all in good, but not fat, condition, lying undisturbed in dry, cool conditions. However, only two dogs were necropsied at any one time point. Although the gross pathology and the histological observations represent snapshots of particular times, the similarity of the dogs, and the holding
Conclusion
Experience in medical and veterinary forensic examinations has shown that establishing an exact time of death may not be feasible but an estimate that defines a specific period of time can be most valuable. This study shows that under the circumstances pertaining during the study, a combination of rectal temperature, environmental temperature, gross pathology and histological changes can provide a scientifically based estimate of the post-mortem interval during the first 10 h following death,
Acknowledgement
The authors are extremely grateful to Michael Thrusfield for his advice on the analysis of the temperature data and for his valuable comments on the text.
References (9)
The evolution of methods for estimating the time of death from body temperature
Forensic Science International
(1988)Wildlife Forensic Field Manual
(1996)- et al.
Temperature-based estimation for the time of death in white-tailed deer
Biometrics
(1984) - et al.
Errors in estimating time since death
Medicine, Science and Law
(1965)
Cited by (46)
Determination of postmortem interval (PMI) using histological changes in the cattle skin – A preliminary investigation
2023, Forensic Science International: Animals and EnvironmentsCharacterization of Traumatic Injuries Due to Motor Vehicle Collisions in Neotropical Wild Mammals
2022, Journal of Comparative PathologyEstimation of postmortem interval in myocardial stab wounds and firearm injuries: An immunohistochemical comparative study using C5b-9 and cardiac Troponin C
2021, Forensic Science InternationalCitation Excerpt :Architecture of the myocardium is stable against autolysis at room temperature and at early period of autolysis, but prolonged autolysis causes gradual loss in the gross architecture of the myocardium by the 12th to 20th days [15]. Besides, another study raised the possibilities for the use of histopathology, as well as IHC, in refining the estimation of the time of death through making up a table of differential findings at various time points (<1day, 3days, 7days and 23 days) after death [16]. Results of the current study showed, in H&E-stained myocardial sections several autolytic changes that slightly appeared in<24 h PM in all groups (control, firearm injury, and stab wound) that increased in intensity with the increase in the postmortem period, till after 48 h PM.
Algorithm for establishing the time of death of a dog based on temperature measurements in selected sites of the body during the early post-mortem period
2018, Forensic Science InternationalCitation Excerpt :The role of veterinary forensics, as a science applied in the pursuit of objective truth, is immensely important in protecting the rule of law. Its role as an applied science has grown considerably in recent years [33]. This is in part directly due to the development of veterinary legislation and legislation associated with animal protection, as well as to society’s increasing awareness and expectations regarding legal protection of animals.
Estimation of the Time Since Death Based on the Post-mortem Histopathological Changes in a Rat Brain: An Observational Study
2023, Journal of Advanced Veterinary ResearchReview of the current and potential use of biological and molecular methods for the estimation of the postmortem interval in animals and humans
2023, Journal of Veterinary Diagnostic Investigation