Burns and Other Heat Injuries
How do Burns Occur?
Burns occur when heat energy is applied at a faster rate than tissue can absorb and spread it. Common sources of heat burns in dogs are fires, heating pads, hair dryers, boiling water, cooking oil, car exhausts and hot pipes. The extent of injury is influenced by the temperature of heat source, time the heat source is in contact, and conductance of tissue.
How are Burns Classified?
Burns are classified according to the depth of tissue affected. This can sometimes be difficult to determine as the depth of injury is not always uniform, and the affected skin surface is often leathery and covered by clotted tissue.
First degree burns are superficial and involve only the skin surface. Affected area is painful, thickened, red and moist. Healing occurs over three weeks by cells forming from the deeper part of skin.
Second degree burns affect a large part of skin thickness. Swelling of tissue below the skin surface occurs and there is noticable inflammation present, but the hairs do not easily pull out. The wounds do heal naturally over several months, but may leave quite extensive scarring. During healing the wounds must be protected against trauma and contamination as ineffective treatment may allow the wounds to progress to third degree burns.
Third degree burns are full thickness skin burns with all skin structures being destroyed. Affected areas appear brown and leathery, and hair can easily be pulled out. These burns are less painful than both first and second degree burns as the skin nerves have been destroyed. Healing occurs via contraction and cell multiplication unless the wound is surgically reconstructed.
Fourth degree burns occur when the burn extends beyond the skin layer. These burns have the same characteristics as third degree burns, but with further tissue damage extending into muscle and bone. Healing occurs via formation of granulation tissues unless surgically reconstructed.
Why are Burns so Serious to the Dog's Life and Well Being?
Burn wounds are sterile or colonised by surface bacteria during the first 24 hours after a burn. However, surface bacteria multiply and invade the tissues under the damaged area within 4 to 5 days of injury as the large volume of dead tissue provides an excellent environment for the growth of bacteria, and the occlusion of local blood supply to the affected area impairs delivery of body defence cells and administered drugs to the area. The condition can be restricted by early removal of sloughing tissue and application of topical antibiotics.
Burns often cause shock and multiple organ failure due to fluid loss, electrolyte imbalances, protein loss, heart depression and increasing viscosity of blood.
What are the Treatments for Burns?
The first priority in treating burn wounds is to minimise tissue loss by administering first aid and preventing shock. Then good wound management is applied to prevent septic complications.
The wounds should be lavaged with cold water or ice packs applied immediately after the injury. The dog should be administered pain relief medication when required.
Minimal supportive therapy is required if the dog suffers a partial thickness burn involving less than 15% of the total body surface area. A dog with burns to more than 15% of the total body surface area requires emergency supportive care which includes placing the dog on an appropriate quantity of intravenous fluids and possibly protein fluids or blood transfusion. Oxygen therapy may also be required if the dog suffers from respiratory distress. High protein and high calorie diets should be fed to counter the increased metabolic demand and protein loss that occur with burn patients. Euthanasia may be considered for a dog suffering from burns to more than 50% of the total body surface area.
Dead tissue must be removed from the wound once the burn victim is stabilised to control sepsis and provide a viable vascular bed for the wound to be closed surgically. This can be performed by surgically debriding the affected area, or by medical treatment.