Nondrowning Asphyxia in Veterinary Forensic Pathology

Abstract

Asphyxia in a forensic context refers to death by rapid cerebral anoxia or hypoxia due to accidental or nonaccidental injury. Death due to nondrowning asphyxia can occur with strangulation, suffocation, and mechanical asphyxia, each of which is categorized based on the mechanism of injury. Individuals dying due to various types of asphyxia may or may not have lesions, and even those lesions that are present may be due to other causes. The interpretation or opinion that death was due to asphyxia requires definitive and compelling evidence from the postmortem examination, death scene, and/or history. Beyond the postmortem examination, pathologists may be faced with questions of forensic importance that revolve around the behavioral and physiological responses in animals subjected to strangulation, suffocation, or mechanical asphyxia to determine if the animal suffered. While there is no prescriptive answer to these questions, it is apparent that, because of physiological and anatomical differences between humans and animals, for some mechanisms of asphyxia, consciousness is maintained for longer periods and the onset of death is later in animals than that described for people. Veterinary pathologists must be cognizant that direct extrapolation from the medical forensic literature to animals may be incorrect. This article reviews the terminology, classification, mechanisms, and lesions associated with asphyxial deaths in companion animals and highlights significant comparative differences of the response to various types of asphyxia in animals and people.

Spatiotemporal accumulation of fatal pharyngeal entrapment of flatfish in harbour porpoises (Phocoena phocoena) in the German North Sea

“…With regard to choking there are two lethal mechanisms described in the literature. The first one is asphyxiation due to a mechanical obstruction of the airway by food items or foreign bodies which inhibit respiration ( McEwen, 2016 ). A different lethal mechanism described in humans is the cardiac arrest due to reflex vagal inhibition which is also known as bolus death and can be caused by food items stimulating the superior laryngeal nerve ( Althoff & Dotzauer, 1976 ).…”

Eternally Vulnerable: The Pathology of Abuse in Domestic Animals

“…Lesions in cases of animal abuse are similar to those reported in people; however, detecting, documenting, and aging these lesions presents a unique challenge to veterinary pathologists because of the many anatomic and physiologic differences between humans and animals, between animal species, and even sometimes even within breeds (7,14,18,32). The greatest challenge to veterinary forensic pathology, though, is the absence of an infrastructure similar to the medical examiner system.…”

“…Species differences in the anatomic blood supply to the brain affect the physiological and behavioral responses to strangulation. The numerous intracranial and extracranial vascular anastomoses in dogs and cats makes them far less susceptible to cerebral isch-emia than people [reviewed by Boghossian (40) and McEwen (14)]. The internal carotid artery is vestigial in cats and small in dogs: the maxillary and vertebral arteries contribute significantly to the cerebral arterial supply and consciousness is maintained for longer periods than in people during strangulation (14).…”

“…Each jurisdiction, though, may have different laws on what constitutes animal abuse and what species or classes of animals are included in that definition (2)(3)(4). Regardless of the definition, animals are subjected to the same types of physical abuse, sexual abuse, cruelty, and neglect as people (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). Unlike people, they are also bred and trained to fight to the death in blood sports, and racing animals may be doped with illicit substances or other compounds that are perceived to give them a competitive edge (16,17).…”

Manual Strangulation of a stray cat

“…Strangulation lesions that have been reported in animal cases include the ligature mark, abrasions or muscle contusions, soft tissue hemorrhage of the neck, laryngealhyoid fractures, conjunctival petechiae, pulmonary edema, congestion or hemorrhage, atelectasis, emphysema, and lesions of acute respiratory distress syndrome; however, none of these lesions are pathognomonic (Munro and Munro 2008;Merck 2012;Bradley 2016;McEwen 2016McEwen , 2018. The critical objective of forensic necropsy for suspected cases of strangulation lies in finding sufficient evidence of compression to support the suspicion.…”