Burns

Basic Information

Definition

A lesion caused by contact with heat or fire

Epidemiology

Species, Age, Sex

• Barn fires are one of the most common causes of burn in horses of any age.

• Horses housed in at-risk barns (no fire detection or protection systems) are more predisposed to burn injury.

Clinical Presentation

Disease Forms/Subtypes

• Burns are classified by the depth of the injury:

• First-degree burns involve only the most superficial layers of the epidermis. These burns are painful and are characterized by erythema, edema, and desquamation of the superficial layers of the skin. The germinal layer of the epidermis is spared, and these burns heal without complication.

• Second-degree burns involve the epidermis and may be superficial or deep.

Superficial second-degree burns involve the stratum corneum, stratum granulosum, and a few cells of the basal layer. Tactile and pain receptors remain intact. Because the basal layers remain relatively uninjured, superficial second-degree burns heal rapidly with minimal scarring, within 14 to 17 days.

Deep second-degree burns involve all layers of the epidermis, including the basal layers. These burns are characterized by erythema and edema at the epidermal-dermal junction, necrosis of the epidermis, accumulation of white blood cells at the basal layer of the burn, eschar (slough produced by a thermal burn) formation, and minimal pain. The only germinal cells spared are those within the ducts of sweat glands and hair follicles. Deep second-degree wounds may heal spontaneously in 3 to 4 weeks if care is taken to prevent further dermal ischemia that may lead to full-thickness necrosis. In general, deep second-degree wounds, unless grafted, heal with extensive scarring.

• Third-degree burns are characterized by loss of the epidermal and dermal components, including the adnexa (Figure 1). The wounds range in color from white to black. There is fluid loss and a marked cellular response at the margins and deeper tissue, eschar formation, lack of pain, shock, wound infection, and possible bacteremia and septicemia. Healing is by contraction and epithelialization from the wound margins or acceptance of an autograft. These burns are frequently complicated by infection.