Environmental and Situational Injuries/Death

Introduction

This chapter will explore causes that may result in environmental and situational injury or death encountered by companion animals in animal abuse scenarios. Situational injury or death may result from burns (thermal, chemical, or electrical in origin) or drowning from submersion in water. Environmental injury or death may result from hyperthermia or hypothermia caused by extremes in temperature through climate, confinement, and lack of shelter.

Burns

Heat may be directed at the tissue in various forms; depending on the duration and intensity, necrotizing lesions may occur (Maxie, 2016). There are two types of heat: moist and dry. Dry heat uses hot air predominantly free from water vapor. Moist heat has moisture content in the form of liquid or vapor (Maxie, 2016). Dry heat causes desiccation and carbonization. Moist heat causes coagulation (boiling) (Maxie, 2016). Heat may affect the body internally via inhalation of steam, smoke, and chemicals. The lowest temperature that tissue can burn is HUF (44°C) (Maxie, 2016).

At the University of Missouri Veterinary Teaching Hospital between 1990 and 1999, 18 patients were treated for burn-related injuries (Pope, 2003). In an 11-year period, in a report from a large metropolitan area, only 22 cats and 27 dogs were treated for smoke inhalation (Pope, 2003). Burns are relatively uncommon in veterinary medicine (Pope, 2003; Garzotto, 2015). When burns are encountered in companion animals, animal abuse as a differential should be ruled out, especially with the frequency that burns are encountered in veterinary medicine. The most common causes of burns in companion animals are electric heating pads, scalding water, fire exposure, heat lamps, vehicle engines, improperly grounded electric cautery units, and radiation therapy (Garzotto, 2015).

Burns are assessed using two major parameters: the degree of injury and the percentage of body surface area. A good place to start is a review of skin anatomy. The outer layer of the skin is the epidermis and the deeper layer is the dermis. The dermis consists of a superficial plexus and a middle plexus; this is where hair and glandular structures originate. Below the dermis resides the hypodermis containing the deep (subdermal) plexus and the panniculus muscle. This layer provides the blood supply to the above skin via the superficial and middle plexuses. There are capillary loops in the superficial plexus that supply the epidermis; these are poorly developed in companion animals compared to humans, resulting in less severe erythema and blistering than human burn victims (Garzotto, 2015).

Burn Classifications

Burns are classified by the cause or mechanism of the injury and by the depth and severity of the body tissue involved (Pope, 2003). Mechanisms of burns are categorized as thermal, radiation, electrical, and chemical (Pope, 2003; Wohlsein et al., 2016). Flames, hot liquids, semi-solids or semi-liquids such as hot metals, auto engines, or tar can cause thermal burns. In small animals, radiation burns are usually caused by therapeutic radiation sources. An electric burn may be caused by direct contact with an electric current or arcing of the current (Pope, 2003; Schulze et al., 2016). Chemical burns are caused by contact with strong acid or alkali substances resulting in tissue destruction by denaturing proteins or interfering with cell metabolism (Pope, 2003; Merck & Miller 2013).

Most of what is known about burn injuries to humans is from studies conducted on animal models. Veterinary medical texts have in-depth chapters detailing the evaluation and treatment of animals who have been burned or who have suffered from smoke inhalation. This material should be reviewed by any veterinarian investigating animal abuse cases involving burn injuries (Sinclair et al, 2006).

Burn wounds have been referred to as first-degree, second-degree, third-degree, and fourthdegree injuries. Terms that are more common now are superficial, partial thickness, and full thickness; these terms are considered more concise for animals (Garzotto, 2015; Pope, 2003). A first-degree burn is superficial and is localized in the external layer of the epidermis. The skin will be erythemic, dry, and painful to the touch. A second-degree burn is a partial-thickness injury that involves the epidermis and partial segments of the dermis. With only a superficial portion of the dermis involved, thrombosis of the blood vessels and leakage of plasma can occur. The hair follicles are usually not affected. Hair follicles can be destroyed in deeper partial-thickness wounds. The skin will appear yellow-white or brown, and sensation is usually minimal except with applied deep pressure (Garzotto, 2015; Sinclair et al., 2006). A third-degree burn wound is a full-thickness injury that obliterates the epidermis and the dermal layers. The skin lacks sensation and appears leathery and charred. A fourth-degree burn wound has similar characteristics to a third-degree burn, however it also involves deeper tissues such as muscle, tendon, and bone (Sinclair et al., 2006; Garzotto, 2015).

Companion animals with burns over 20% of their total body surface area (TBSA) may develop significant metabolic compromise (Garzotto, 2015). Animals with over 50% of their TBSA have a poor prognosis (Garzotto, 2015). TBSA can be calculated or estimated.