NAVLE Integumentary

Canine Burns Study Guide

Burns are painful injuries involving partial or complete skin damage caused by heat (thermal burns), chemicals, electricity, friction, cold, or radiation.

Overview and Clinical Importance

Burns are painful injuries involving partial or complete skin damage caused by heat (thermal burns), chemicals, electricity, friction, cold, or radiation. While burns are relatively uncommon in dogs compared to other traumatic injuries, they can be serious and even life-threatening when they occur. Burns represent a significant emergency medicine topic on the NAVLE due to their complex pathophysiology, need for immediate intervention, and potential for systemic complications.

Thermal burns are the most common type encountered in veterinary practice, often resulting from domestic accidents (scalding liquids, contact with hot surfaces, house fires), inappropriate use of heating pads during anesthesia, or hot dryer injuries at grooming facilities.

Burn Type Causes and Characteristics
Thermal Burns Most common type. Caused by flames, hot liquids (scalds), steam, hot surfaces, or heating devices. Includes scalds (boiling water, hot oil), contact burns (heating pads, dryers), and flame burns (house fires). Severity depends on temperature and duration of contact.
Chemical Burns Caused by acids, alkalis (drain cleaners, lye), or other caustic substances. Alkali burns penetrate deeper than acid burns. Can cause systemic illness if ingested. Require immediate copious water lavage.
Electrical Burns Most common from chewing on electrical cords (especially puppies). Can cause tissue charring at contact site, severe internal injuries to heart and lungs. May result in non-cardiogenic pulmonary edema (NCPE) with delayed onset up to 36 hours.
Friction Burns Also known as rope burns, carpet burns, or road rash. Occur when skin is abraded by mechanical contact with hard surfaces. Combination of abrasion and heat burn.
Cold Burns (Frostbite) Caused by severe or prolonged cold exposure. Ice crystals form causing cell damage and necrosis. Extremities (ears, tail, digits) most susceptible.

Burn Classification

Classification by Etiology

High-YieldOn NAVLE, electrical cord bite injuries in puppies are frequently tested. Remember that clinical signs may be delayed up to 36 hours, and non-cardiogenic pulmonary edema is a major complication. Always recommend monitoring even if patient appears initially stable.

Classification by Depth

Burn depth is classified according to the layers of skin affected. In veterinary medicine, the terminology has evolved from the classic human degree system to a more descriptive system based on tissue layers affected.

NAVLE TipRemember that full-thickness burns are LESS painful than partial-thickness burns because nerve endings are destroyed. A patient with an extensive burn reporting minimal pain may have a more severe injury than one in significant pain.
Classification Tissue Affected Clinical Signs Healing
Superficial (1st degree) Epidermis only Red, dry; painful; no blisters; like sunburn Heals in 2-5 days without scarring
Superficial Partial-Thickness Epidermis + superficial dermis Blisters; moist, pink; very painful Heals 10-14 days; minimal scarring
Deep Partial-Thickness Epidermis + deep dermis Mottled pink/white; reduced sensation 3-6 weeks; significant scarring; may need grafting
Full-Thickness (3rd degree) All skin layers + subcutaneous Leathery, charred; painless; eschar Requires surgery and grafting
Subdermal (4th degree) Through to fat, muscle, bone Charred; exposed structures Extensive reconstruction; often fatal

Total Body Surface Area (TBSA) Estimation

Estimating the percentage of TBSA affected is critical for determining burn severity, guiding fluid resuscitation, and predicting prognosis. The Modified Rule of Nines has been adapted for canine patients.

Modified Rule of Nines for Dogs (Mesocephalic)

Clinical Significance of TBSA

  • Local burns: Less than 20% TBSA - manageable with local wound care
  • Major burns: Greater than 10-15% TBSA - systemic inflammatory response expected
  • Severe burns: Greater than 20% TBSA - life-threatening systemic complications
  • Critical burns: Greater than 50% TBSA - poor prognosis; euthanasia should be discussed
High-YieldBurns greater than 20% TBSA in adults (or greater than 10% in pediatric/geriatric patients) require formal fluid resuscitation. The NAVLE frequently tests fluid calculations for burn patients.
Body Region Percentage of TBSA
Head 14%
Neck 9%
Each Forelimb 9% each (18% total)
Thorax 18%
Abdomen 14%
Each Hindlimb 11% each (22% total)
Pelvis and Tail 5%

Pathophysiology of Burn Injury

Local Response: Jackson's Burn Wound Model

The burn wound consists of three concentric zones of tissue injury:

Systemic Response to Severe Burns

Burns affecting greater than 20% TBSA trigger a massive systemic inflammatory response:

  • Cardiovascular: Capillary leak, hypovolemia, decreased cardiac output, burn shock (peaks 8-12 hours)
  • Metabolic: Hypermetabolic state (2-3x normal energy needs), protein catabolism, electrolyte disturbances
  • Immunologic: Impaired cell-mediated immunity, decreased neutrophil function, high infection risk
NAVLE TipMemory tip - "SHIFT": Systemic inflammation, Hypovolemia (capillary leak), Infection risk, Fluid loss (evaporative), Tissue hypermetabolism.
Zone Characteristics
Zone of Coagulation (Central) Irreversible tissue necrosis. Direct thermal injury causes immediate cell death. Cannot be salvaged.
Zone of Stasis (Intermediate) CRITICAL - potentially salvageable. Decreased perfusion; cells viable for 24-48 hours. Prone to burn wound conversion. Goal is to preserve this tissue.
Zone of Hyperemia (Peripheral) Increased blood flow from inflammatory response. Usually recovers fully unless complicated by infection.

Treatment

Emergency First Aid

Thermal Burns

  • Remove from heat source
  • Cool with room temperature to cool (2-15 C) running water for 20-30 minutes
  • Do NOT use ice or ice water (causes vasoconstriction and hypothermia)
  • Cover with sterile, non-adherent dressing
  • Do NOT apply butter, oils, or home remedies

Electrical Burns

  • CRITICAL: Disconnect power source before touching patient
  • Check airway, breathing, circulation
  • Initiate CPR if indicated

Fluid Resuscitation

Aggressive fluid resuscitation is critical for burns affecting greater than 20% TBSA in adults or greater than 10% in pediatric/geriatric patients.

Parkland Formula

Example Calculation

A 25 kg dog with 30% TBSA burns:

  • Total fluid = 4 x 25 x 30 = 3,000 mL in 24 hours
  • First 8 hours: 1,500 mL (187.5 mL/hr)
  • Next 16 hours: 1,500 mL (93.75 mL/hr)

Monitoring Goals

  • Urine output: 1-2 mL/kg/hr (primary endpoint)
  • Heart rate: Return to normal range
  • Blood pressure: Maintain adequate perfusion
NAVLE TipParkland formula provides an ESTIMATE only. Adjust fluids based on clinical response. Under-resuscitation causes burn shock; over-resuscitation causes pulmonary edema. Monitor urine output as primary endpoint. For cats, reduce calculated volume by 25-50%.

Wound Management

Topical Antimicrobial Therapy

High-YieldSilver sulfadiazine is the gold standard topical agent for burns. Be aware of potential keratoconjunctivitis sicca (KCS) with prolonged use in dogs. Do not use in animals with sulfonamide allergies.

Special Considerations

Electrical Burns

Electrical cord bite injuries are common in puppies. The electrical current converts to thermal energy causing tissue burns and may cause systemic effects.

Clinical Features

  • Oral burns: Characteristic lesions at lip commissures, tongue, palate
  • Pulmonary edema: Non-cardiogenic (NCPE); onset may be delayed 12-36 hours
  • Cardiac effects: Arrhythmias (may be immediate or delayed)

Treatment

  • Oxygen therapy
  • Diuretics (furosemide) for pulmonary edema
  • Soft food diet for 2+ weeks during oral healing
  • Monitor for 36-72 hours even if initially stable
NAVLE TipKey points for electrical burns: (1) Disconnect power BEFORE touching patient, (2) NCPE may be delayed up to 36 hours, (3) Even stable-appearing patients need monitoring, (4) Chest radiographs may be normal initially - repeat in 24-48 hours.

Smoke Inhalation Injury

Smoke inhalation significantly worsens prognosis. Three primary mechanisms: thermal injury to upper airways, chemical injury from toxic gases (CO, cyanide), and particulate injury.

Clinical Signs

  • Singed whiskers/facial hair, soot in nares or oral cavity
  • Coughing, dyspnea, stridor, wheezing
  • Cherry-red mucous membranes (CO toxicity)

Treatment

  • High-flow oxygen: Displaces CO from hemoglobin
  • Bronchodilators: Albuterol (nebulized), terbutaline
  • Nebulization and coupage: Helps clear particulate matter
High-YieldDogs and cats with smoke inhalation alone (no burns) have survival rates up to 90%. Concurrent burns significantly worsen prognosis. Pulmonary changes may be delayed 24-72 hours.
Agent Indications Notes
Silver Sulfadiazine 1% First-line for 2nd/3rd degree burns Broad-spectrum. May cause KCS in dogs with prolonged use. Apply 1-2x daily.
Triple Antibiotic Ointment Superficial burns; minor wounds Contains neomycin, polymyxin B, bacitracin.
Medical-Grade Honey Natural antimicrobial; promotes healing Creates moist environment. Promotes autolytic debridement.

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