A UK-based retrospective study of fatal non-drowning asphyxia cases in dogs and cats

Death by asphyxia is defined as the prolonged and fatal deprivation of oxygen and/or blood to the brain and other vital organs. Strangulation, smothering, hanging, drowning, choking, suffocation and chemical asphyxia are considered the main modalities in which asphyxiation can occur. The study of injury patterns is crucial for assisting veterinary forensic experts in identifying the cause and manner of death with a higher degree of certainty. A retrospective study of necropsy cases identified using the keywords "asphyxia", "anoxia", "hypoxia", "strangulation", "hanging", "choking", "smothering" and "suffocation" was performed. A total of 33 dogs and 16 cats were included in the study. In 67 % of cases, asphyxiation was suspected from the circumstances in which the victim was found. Whereas strangulation was the most significant modality of asphyxiation in dogs (25/33, 76 %), smothering or airtight confinement were more prevalent in cats (6/16, 38 %). Some findings that are highly indicative of asphyxiation in humans were rare or even absent in our study cohort, such as external skin bruising and fracture or dislocation of the hyoid apparatus. Most lesions were confined to head and neck, including bilateral scleral reddening, meningeal congestion, circumferential laryngeal reddening, selective subcutaneous congestion and bruising within the superficial muscles and subcutaneous tissues, consistently accompanied by severe pulmonary congestion and oedema. Whereas no single lesion was considered pathognomonic; the combination of several lesions highly indicated asphyxiation. A significant association between some lesions, the modality of asphyxiation and victim's species was also noted.