Veterinary Forensic Science: An Emerging Area
WHAT IS FORENSICS?
Forensics is the scientific presentation of evidence to:
- Establish that a crime occurred
- Determine a crime’s timeline
- Assess elements of a crime
- Provide perspective regarding the nature of a crime
- Confirm or contradict events related or circumstantial to a crime.
As a science, forensics does not determine guilt or innocence, right or wrong. Instead, evidence is used to provide an explanation and account for the events that occurred in relation to a crime.
Veterinary forensic Science is a relatively new and emerging area. The word ‘forensic’ was derived from the Latin word ‘forensis’ meaning ‘before the forum’. Fortunatus Fidelis, an Italian doctor, is regarded as the first person to practice modern forensic medicine in 1598. Forensic Science is an interdisciplinary Science which involves the application of knowledge of Veterinary and other life sciences to solve the veterolegal cases with reliable and scientifically proved facts. Though the use of veterinary forensic science has increased during the last few decades but the Veterinary forensic medicine in India is still an infant specialist area. The Veterinarians, many a times, are presented whole or partial bones, carcass, blood samples, teeth, claws, tusks, hair, hides, fur, feathers etc. for identification to solve vetrolegal cases. If the samples are large enough they can easily be identified on the basis of their gross morphology as each species has its own characteristic features. The sex of the species can be determined from the bones like pelvis, skull, mandible, teeth, vertebrae and long bones extremities with the varying degree of accuracy (Isik and Blachelioglu 2003). It has been reported that even Foramen magnum (FM) dimensions are very important anatomical landmark in sex determination (El Barrany et al. 2016). If the fragments of bones are large enough their species can be identified. Histologically, the concept of plexiform bone has been considered to be a general determinant of human and nonhuman bone tissue. Human cortical bone can be differentiated from large mammals like cattle, buffalo, horse and deer on the basis of absence of plexiform bone in humans. Besides this histomorphometry (Haversian system diameter and Haversian canal diameter) can also play an important role in species identification (Hillier and Lymne, 2007; Uppal and Bansal 2008; Uppal et al. 2015). Species can also be identified on the basis of morphology of hair. Hair shaft has outer cuticle, cortex and inner medulla. The diameter of medulla of human hair ranged between 5 to 20 µm and the diameter of medulla of animal hair between 20 to 100 µm (Kshirsagar et al. 2009). The scanning electron microscopy of hair surface provides very valuable information regarding species identification (Broeck et al. 2001). Like, the bovines show a thin cuticle, coronal scales in mosaic with serrated edges and flattened irregularly whereas in equines it is thin and imbricated with irregular waves and intermediate spaces. The cortex in the bovines is thin crust dark brown and not pigmented whereas in equines the cortex is dark brown, with light texture and isolated dark brown and black pigments (Mendiburta et al. 2021). The species can be identified on the basis of morphology of the blood cells mainly RBCs, eosinophils and neutrophils. The most appropriate way of identification of different species is by testing the genomic DNA by polymerase chain reaction (PCR) amplification. The TP53 gene can be used as a potential animal species identifier as it produces fragments of different sizes between species (Bellis et al., 2003; Uppal et al., 2011). Two complementary techniques, simple sequence repeat anchored (SSR) PCR and PCR-restriction fragment length polymorphism (RFLP), could be used successfully as routine methods in forensics for sensitive, rapid, simple and inexpensive identification of the species in bloodstains (El-Sayed et al. 2010). DNA profiling is the most reliable method of species identification. STR (Short Tendem Repeat) loci are listed on various websites for different species like dog, cat, sheep and bovine (Linacre 2021). Veterinary Forensics also play an important role in Pouching (an illegal hunting of wild animal species for the aim of obtaining valuable), illegal collection and trade and wildlife trafficking. The trade in ivory is leading to the extinction of elephants from many Asian and African countries. An elephant tusk is a potential source of DNA. DNA typing from the tusk will open the possibility to identify the number of elephants slaughtered. Such knowledge will aid in forensic investigations, or at least in highlighting the extent of the illegal trade. The STR multiplexes have also been developed for many wild animal species like elephants, bears, wolves and badgers (Linacre 2021). The STR markers have also been created for the one horned Indian rhino (Rhinoceros unicornis) as a part of the official RhODIS-India program as this species has also suffered due to poaching for their horns (Ghosh et al. 2021). Although veterinary students are taught jurisprudence yet scanty attention is usually paid to the role of the veterinarian as an expert or advisor in veterolegal cases. Veterinary Forensic has a ubiquitous role but it is not a bonafide subject within the veterinary curriculum and is given little or no recognition. There is still lack of definite status, paucity and scattering of literature and data which hampers the ability of veterinarians to contribute their skills and knowledge. Keeping in view the need of this emerging area, the educational institutions should provide opportunities in veterinary forensics by offering training/short courses for Veterinary Clinicians. A collaborative approach involving experts in different areas of Forensic Science like Anatomy, Pathology, Microbiology, diagnostic imaging etc. will strengthen this aspect. Till date the technological advancements made in human forensic genetics have been applied in animal forensic, but not successfully as unlike human forensic genetics, forensic DNA analysis for animal protection suffers very low genetic markers and secondly lack of validity in the animal forensic analysis (Mgimba, 2017). The Veterinary practitioners have to play an important role in this emerging field of Veterinary Forensic Science. There is a need to enhance the awareness of veterinarians and to introduce teaching and specialized training regarding Veterinary Forensic. We need to establish systems and protocols similar to those used in human forensic medicine. Research and development of new techniques are essential. We need to compile the available data. Although the Veterinary Forensic is yet not a recognized discipline but is rapidly evolving and new challenges demand new approaches.
Veterinary forensics is relatively new and rapidly developing field yet to get recognition in international forum. However, keeping aside, the complexity of multispecies variation, forensic veterinary pathologists are working tirelessly to establish this discipline in global sector. The job of forensic veterinary pathologists is very confusing as it comprises of multispecies variation ranging from tiny and timid companion animals to large and ferocious wildlife creatures. For this reason, present write-up concentrates on 4 selected aspects of forensic veterinary pathology (Ottinger et al., 2014).
A. Estimation of the age of skin wounds
B. Estimation of the age of bruising
C.Diagnosis of drowning
D. Estimation of the time since death.
A.Estimation of the age of skin wounds Wound examination is the toughest job for a veterinary forensic pathologist as it acts as substantial evidential interest to determine whether the wound has occurred before or after death. A well-developed wheal type response around the wound margin and leucocytic infiltration upon microscopical examination is a clear guide to anti-mortem injury. As certain leucocytes are also found after death, so, the significant period elapsed between time of injury and death of animal acts as the vital cog in determining the anti-mortem nature of wound. Ideally forensic veterinary pathologists should have a crystal-clear understanding of the pathophysiology of wound healing process in the animal under investigation. The healing process is basically divided into 3 phases: – inflammatory, proliferative and maturation. Inflammatory phase is marked by events like early blood clotting and development of extracellular matrix followed by proliferative phase that is characterised by shifting of neutrophil predomination in early inflammatory response to macrophage invasion in older lesions, angiogenesis, fibroplasia (myofibroblasts synthesise glycoproteins) and epithelisation (formation of vascular network and collagen synthesis) which ultimately leads to maturation or remodelling. These observations facilitate forensic veterinary pathologists to develop evidence against time that has been elapsed since injury (Hosgood, 2006).
B. Estimation of age of bruising Scientifically bruise can be defined as “hematoma of tissue”. In a broader sense, it can be defined as the crushing of cells and blood vessels in the injured area resulting into extravasation of blood and cellular fluids. On later stages, it may involve degeneration, inflammation of muscle and adipose tissue. Age of bruise can be calculated based on intensity of trauma which is the primary focus of forensic investigation. There are 2 types of trauma – • Blunt force trauma which includes lacerations, abrasions, and contusions. Lacerations mainly affect collagen fibres of body that leads to loosening of elasticity. Abrasions result from rough force applied over skin which results in scraping of epidermis leading to hyperemic epidermal layer. Contusions are simple extravasations of RBC into tissue that is manifested by petecchiae, ecchymoses, and hematomas. • Sharp force trauma includes incisions that arises due to application of sharp objects like scalpel, knives, scissors, ice pack, nails which sometimes lead to bone fracture (Viner and Kagan, 2018) Gross examination of bruises leads to estimation of ages based on the time duration and gradation of lesions (Munro and Munro, 2013). • 0 – 10 h post injury – Red and haemorrhagic. • 24h – Dark red • 24 -38h – watery in consistency. • Over 3 days – rusty orange and soapy touch. Microbiological examination includes Fouchet’s test with the help of Fouchet’s reagent which involves bilirubin estimation that is formed by haemoglobin degradation (Munro and Munro, 2013) • Until 50 – 60 h post injury – no colour development • 60 – 72 h – very light to blue colour • 3 – 5-day old bruises – diffuse dark green at periphery with brown centre • 5 – 8-day old bruises – little or no blue colour
C. Diagnosis of drowning -Exploration of drowning cases in domestic and companion animals serve as the most challenging job for a forensic pathologist. Detailed gross and microscopical examinations are required to establish the conformation regarding death outside or inside water. Further, taphonomonic changes due to maceration, decomposition, and scavenging must be differentiated from antemortem lesions that may indicate struggling or entrapment. Microscopic changes may include alveolar overdistension, alveolar septa attenuation, narrowing of alveolar capillaries, haemorrhagic oedema within the alveoli and aspirated foreign material in bronchi. Swallowing of excess amount of water leads to tear in stomach wall which acts as pathognomonic lesion of drowning (Viner and Kagan, 2018).
D. Estimation of the time since death Estimation of time since death seems to be a routine affair in human forensic cases but in veterinary perspective, matter is relatively complex as it is driven by multiple factors depending upon the category and species involved. But usually 2 basic approaches are essential to estimate the time of death – • Measurement of changes that took place at a known rate (Rigor mortis, Algor mortis, Putrefaction). • Measurement of changes that took place at an unknown rate (extent of digestion of last meal etc.). There are certain methods adopted in veterinary forensics investigation to demonstrate the time elapsed since death like • Temperature based methods • Postmortem chemistry • Gross appearance of body based on rigor mortis, eye shape, colour, luminosity, decomposition etc. • Histopathology and electron microscopy • Radiology • DNA and RNA analyses • Environmental and associated evidence.
As veterinary forensics field is expanding, continued research in this area will boost up the knowledge level of veterinarians and paraveterinarians who are investigating these cases involving animals. The biggest challenge in this field is cognitive biases which are inherent human factors that cannot be wiped off. But the role of veterinary pathologists is crucial as they should provide a balanced and factual interpretation of autopsy findings based on the history and evidence not on preconceived assumptions. Currently veterinary forensics field laid exciting possibilities of expansion and refinement when it would be collaborated with specialists of other disciplines including those of diverse subjects like DNA technology, forensic entomology, electron microscopy and ballistics to arrive at a certain investigative conclusion
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
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Reference-On Request.
