Animal Models in Forensic Science Research: Justified Use or Ethical Exploitation?

The current state of forensic imaging - post mortem imaging

Over the last few decades, forensic imaging has become an essential part of current forensic practice. The aim of this 4-part review is to provide a comprehensive overview of forensic imaging over the first 25 years of this century. After a brief historic review, this first part details the advantages and limitations of post-mortem imaging for the indications most frequently encountered in daily practice.

Zebrafish: A Cost-Effective Model for Enhanced Forensic Toxicology Capabilities in Low- and Middle-Income Countries

Low- and middle-income countries (LMICs) are increasingly challenged by the rising burden of medicolegal cases. Traditional forensic infrastructure and in vivo rodent models often have significant limitations due to high costs and ethical concerns. As a result, zebrafish (Danio rerio) are gaining popularity as an attractive alternative model for LMICs because of their cost-effectiveness and practical advantages. Zebrafish have a lower acquisition cost, require less demanding husbandry, and have rapid development cycles, all of which facilitate faster and more economical toxicological studies, even in limited laboratory space. Additionally, the optical transparency of zebrafish embryos and larvae allows for non-invasive in vivo observations, reducing the need for extra resources. Research has shown that zebrafish can effectively investigate the behavioral, developmental, and cardiotoxic effects of various novel psychoactive substances (NPSs), including synthetic opioids, cathinones, and hallucinogens. They also excel in metabolic profiling, producing a broader range of metabolites than other models, with significant overlap in human metabolism. The presence of mammalian-like metabolic enzymes further positions zebrafish as a valuable tool for understanding human NPS metabolism and predicting potential effects. Notably, they can identify metabolites that traditional models may not detect, underscoring their potential for novel metabolite discovery. Despite these advantages, standardizing data collection protocols and addressing interlaboratory variability are crucial challenges that must be overcome for the widespread adoption of the zebrafish model. However, ongoing global efforts are paving the way to address these limitations and ensure the successful integration of zebrafish models into the field of forensic toxicology. This review highlights the potential of zebrafish as a cost-effective and versatile model for LMICs, emphasizing their growing application in NPS research and forecasting broader adoption in forensic toxicology.

Use of animals in dental research: Trends and ethical reflections

This study aimed to survey and analyze the profile of experimental dental research in animals, verifying its trends. We evaluated studies developed with the use of animals in vivo, published in 10 dental journals with high impact factors, from 2015 to 2020. From 1652 studies retrieved, 594 involved in vivo experimentation on animals and were analyzed further. Rats were the species most used and with the highest mean of animals per study. Ferrets, although presenting the lowest rate of publications, had the second highest mean of animals per study. Periodontics was the dental specialty with the highest number of publications, while oral rehabilitation had the lowest number. The data on the institution responsible for reviewing animal research protocols approval, sample size, anesthesia and analgesia were provided in 93.10%, 83%, 70.54% and 23.74% of studies, respectively. In 53% of studies, euthanasia was specified and anesthetic overdose was the method most used. Over the period analyzed, there was a reduction in animal studies in vivo, and periodontics was the specialty that most used this experimental model. Although most studies mentioned approval by an ethics committee, some publications neglected to mention sample size, anesthesia and euthanasia. The omission of essential information may raise scientific and ethical concerns.

A review of experimental design in forensic taphonomy: moving towards forensic realism

Forensic taphonomy as a discipline requires standardization to satisfy Daubert criteria for scientific data to be admissible in court. In response, there has been a shift towards quantification of methodology and estimating the postmortem interval. Despite these advances, there are still biases and limitations within the discipline not explicitly addressed in the early stages of experimental design nor in final published works. In this article, unresolved debates with respect to the conductance and reporting of forensic taphonomic research are reviewed, beginning with the nature of experimental cadavers, human or animal analogues and their body size, and second, the forensic realism of experimental setups, specifically with respect to caging, clothing and number of carcases. Pigs, albeit imperfect, are a good model to gain a general idea of the trends that may be seen in humans in subsequent validation studies in facilities where human donors are available. To date, there is no consensus among taphonomists on the extent of the effect that body mass has on decomposition progression. More research is required with both human cadavers and non-human analogues that builds on our current knowledge of forensic taphonomy to answer these nagging questions. This will enable the discipline to make the reliable assumption that pigs and donor decomposition data can be applied to homicide cases. A suite of experimental design aspects is suggested to ensure systematic and standardized data collection across different biogeoclimatic circumstances to identify and quantify the effects of potential confounding variables. Such studies in multiple, varied biogeographic circumstances with standardized protocols, equipment and carrion will facilitate independent global validation of patterns. These factors are reviewed to show the need for adjustments in experimental design to ensure relevance and applicability of data within locally realistic forensic situations. The initiation of a global decomposition data network for forensic taphonomists is recommended.

Key points

Pigs are a valuable, albeit imperfect, proxy for human decomposition studies.

There are few or conflicting data on effects of carcase size, carrion ecology, exclusion cages and scavengers.

We recommend single, clothed, uncaged carcases for baseline research to reflect regionally specific forensic casework.