19: Environmental Disorders

SECTION 19 Environmental Disorders



Section Editor: Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO



Burns

Electrical Cord Injury

Heat Prostration

Shock

Venomous Snake Bites


Burns


Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO



BASIC INFORMATION



Description


Burns may occur from exposure to heat or flames (thermal burns), caustic chemicals, or electrical currents. (See handout on Electrical Cord Injury.) The severity of the burn is determined by the depth and extent of the injury. The extent of the burn is estimated as a percentage of total body surface area (TBSA) affected.


Burns are classified as superficial (first-degree) burns if only the skin and fur are affected. Partial-thickness (second-degree) burns involve the skin, its glands, and superficial tissue. Full-thickness (third-degree) burns destroy all the layers of the skin and nearby tissues and may destroy fat, muscles, and bone.



Causes


Several types of thermal burns may occur and have a variety of causes:


• Dry, direct heat injuries may be caused by heating pads and lamps, radiators, stoves, light bulbs, and other hot surfaces.

• Wet, direct heat injuries may be caused by hot water, steam, hot tar, oils, or other liquids.

• Common sources of flame-induced injuries include house or barn fires, campfires, forest fires, and malicious burnings.

Chemical injuries may involve several classes of materials, as in the following examples:


• Acids: some toilet bowl cleaners, battery acid, metal and concrete cleaners, rust removers

• Alkaline bases: bleach, drain and oven cleaners, ammonia, Lysol, certain pool chemicals, lime

• Oxidizing agents: bleach, peroxide, manganates

• Solvents: turpentine, paint thinners, gasoline, kerosene


image Clinical Signs


Superficial burns cause redness, swelling, and ulceration of the skin, with singeing or loss of fur. Partial-thickness burns cause these signs as well as blistering, edema, and thickening of the skin. Deeper partial-thickness burns may be yellow or whitish in color, dry, and less sensitive to touch. Full-thickness burns may be charred and have a leathery texture, with no recognizable normal skin. Most burns are painful, but full-thickness burns may initially be nonpainful, because nerve endings are destroyed. Depending on the source of the burn, other serious signs may be present as a result of smoke inhalation, electrical current exposure, shock, and damage to other organs.



image Diagnostic Tests


Diagnosis is often determined by the history and physical examination. If the animal was exposed to chemicals, bring the container to the veterinary hospital. Numerous diagnostic tests may be recommended for animals with severe burns, because they can cause problems with the lungs, heart, gut, urinary system, and overall circulation.



TREATMENT AND FOLLOW-UP




image Treatment Options


Treatment involves care of burn wounds and all the other systemic changes caused by the burns. In general, the treatment of shock, respiratory distress, and cardiac problems takes priority over treatment of the wounds. Seriously injured animals may require oxygen, fluid therapy with crystalloid or colloid solutions, and blood or plasma transfusions. (See the handouts for each of these therapies.) Fluids may be supplemented with electrolytes and glucose (sugar), because many metabolic problems arise with burns. Intensive nursing care, prevention of hypothermia, pain control, and therapy for liver and kidney damage may all be needed.


Proper wound care is important to prevent infections and decrease the amount of body fluids lost by evaporation. Wound care often involves applications of ointments, such as silver sulfadiazine, silver nitrate, and mafenide acetate, and frequent bandaging. Bandage changes must be done carefully, using a sterile technique.


Burned tissue changes a lot over the first several days, and areas that are not going to survive become more obvious over time. Dead skin and tissue must be softened and removed. In some cases, medicated ointments or hydrotherapy (such as a gentle whirlpool bath) can be used, but in other cases repeated surgical procedures are necessary. Once all tissue death has occurred and the dead material has been removed, large burn sites may be prepared for grafting. If skin grafts are anticipated, your pet may be referred to a veterinary surgery specialist for this procedure.


Nutritional support is very important during the recovery period, because the body must expend a great deal of energy to heal itself from burns. A high-calorie, high-protein diet is often recommended.



image Follow-up Care


With severe burns, intensive monitoring and repeated laboratory testing are often needed for days. Close monitoring of body weight and nutritional status may be continued for weeks to months.



Prognosis


Prognosis is inversely proportional to the severity of the burn. Other organs are likely to be affected with burns that involve more than 20% of the TBSA, and animals rarely survive if more than 50% of the TBSA is burned. Healing of severe burn wounds may take up to 6 months, and multiple surgeries may be needed.



SPECIAL INSTRUCTIONS:



Electrical Cord Injury


Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO



BASIC INFORMATION



Description


These injuries usually occur when animals chew on live electrical cords. Puppies and kittens are affected most often, because the cords make attractive play items. Electrical energy is transformed into heat at the point where the exposed wires touch tissues, so a local burn results. Electrical current can also travel into the body, disrupting many normal functions. The severity of injury is proportional to the duration of exposure and the intensity of the electrical current.



Causes


Exposed electrical cords are the most common source of injury. Cords that are temporarily located in open areas, such as those used to power Christmas tree lights, floor fans, space heaters, or outdoor tools, may draw an animal’s interest and attention. Although uncommon in small companion animals, lightning strikes and exposure to live power lines can also cause electrical injuries.



image Clinical Signs


When electrical cords are bitten, pale yellow, tan, or gray burns may be present on the lips and tongue. With high arcing currents, copper deposits are also left at the site. Systemic effects of the electrical current include muscle spasms and seizures; irregular heart rhythms (arrhythmias) and cardiac arrest; respiratory distress and arrest; vomiting and abdominal pain; and unconsciousness. The gums of the mouth may be pale or blue (cyanotic) in color.


Filling of the lungs with fluid (pulmonary edema) is a delayed effect of electrical cord injuries that may produce coughing of bloody or pink fluid and difficulty breathing 12-36 hours after exposure. Arrhythmias may also occur hours after the injury.



image Diagnostic Tests


The diagnosis may be obvious if the injury was witnessed or the animal was found unconscious, convulsing, or in respiratory distress near a damaged electrical cord. The presence of oral burns and other compatible clinical signs may allow a presumptive diagnosis, especially in a young animal. Laboratory tests may be recommended to rule out other diseases that cause similar clinical signs; the results of these tests are usually normal in animals with electrical cord injuries. Chest x-rays are often performed if pulmonary edema is suspected.



TREATMENT AND FOLLOW-UP




image Treatment Options


Disconnect the electricity before touching the animal! Remove the animal from the source of current, and clear its mouth and nostrils of any mucus or fluid. If the animal is not breathing, start mouth-to-nose breathing. Seek veterinary care immediately if the animal is having muscle spasms, seizures, difficulty breathing, or weakness or is collapsed or unconscious.


At the veterinary clinic, therapy for shock is started with oxygen, intravenous fluids, and cardiopulmonary resuscitation (CPR), as needed. (See the handouts on Shock and Cardiopulmonary Resuscitation.) If the animal is not breathing on its own, it may be attached to a mechanical ventilator, if one is available.


Hospitalization may be recommended, even for animals with minimal clinical signs, so that they may be closely monitored for 24-48 hours to observe for the onset of pulmonary edema and cardiac arrhythmias. Therapy for the edema may include oxygen therapy, diuretics (such as furosemide), and drugs to dilate the airways (such as terbutaline or aminophylline). Anti-arrhythmic medications are administered as needed.


Minor oral burns are often cleaned with an antiseptic solution. Most burns heal without surgery, but severe, full-thickness (third-degree) burns may require surgery if the tissue dies and becomes necrotic. Hard foods, chew toys, and treats are avoided until the burns have healed. Antibiotics may be given for secondary infections, and pain medications are administered as needed.

Related posts:

  1. 6: Endocrine System
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  3. 2: Cardiovascular System
  4. 15: Infectious Diseases

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Sep 11, 2016 | Posted by in SMALL ANIMAL | Comments Off on 19: Environmental Disorders

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