Burns

Definition

Burns are injuries to tissues as a result of contact with heat, electricity, chemicals, friction or abrasion; or more specifically:

Thermal burns are caused by exposure to heat / flames, scalding liquids, and steam.
Electrical burns result when electrical current passes through the body to ground as in the biting of an electrical cord.
Chemical burns are caused by contact, ingestion, inhalation, or injection of alkalines or vesicants.
Friction or abrasion burns result when skin is rubbed against a course, abrasive surface.

Clinical Signs

Any of the following clinical signs may be observed depending on type, location, and severity of burn:

First Degree (Superficial) Burns

Epidermis (outer layer of skin) erythematous (reddened)
Blisters not usually present
Hair/fur singed but attached
Minor pain

Second Degree (Partial Thickness) Burns

Epidermis and part of dermis affected. Tissue erythematous, or tan.
Blistering of the skin.
Edema (swelling) at the site and the surrounding tissue.
Hair/fur or whiskers at site may or may not be intact, and if present singed.
Pain is present.
A peeling of the skin.
Eschar (pronounced es-`kar) which is a dry scab or slough formed on the skin as a result of a burn or a corrosive or caustic substance.

Third Degree (Full Thickness) Burns

The destruction of the epidermis and dermis.
Possible damage to muscle and tendon.
Tissue that is pale, white, grey, or charred.
The loss of hair/fur or whiskers.
Pain will be absent since nerve endings are destroyed.
The presence of eschar.

Smoke inhalation

Damage to lungs
Wheezing
Congestion

Additional signs for burns affecting the oral cavity

Tissue of the tongue, buccal or lingual mucosa may appear reddened, blistered, tan, gray, or pale yellow with charred margins.
The presence of eschar.
An increased oral sensitivity.
The presence of drooling.
A hesitance to eat or drink due to pain, sensitivity, or swelling of tissues in or around mouth.

Systemic Effects in Second degree, Third degree, and Electrical burns

Hypovolemic shock (rat may appear to be shivering, feel cool to touch, be less responsive or unresponsive)
Hyperventilation (breathing more rapidly than normal)
Respiratory distress or arrest
Seizures
Cardiac arrhythmias
Cardiac arrest
Muscle tetany (muscle spasm)
Dehydration
Muscle weakness
Neurological impairment

Etiology

Burns may be caused in a variety of ways such as thermal, chemical, electrical, or friction and abrasion.

Burn injuries can disrupt the normal protective function of the skin which can result in both local and systemic effects. Local injury, at the site of the burn, results in the release of histamine and vasoconstriction followed by vasodilation and increased permeability of the capillaries. Damage to tissue escalates as swelling, ischemia and cell death occurs. In systemic effects, shock, tissue loss, and suppression of the immune system are involved.

With electrical burns, heat is generated as electrical current passes through body tissue. It is the thermal energy released that actually causes the burn injury. Alternating Current (AC) that is found in most homes uses a flow of electricity that regularly reverses direction. Direct Current (DC) that which is found with batteries or high voltage power lines uses a flow that has constant direction. It is the alternating current that is more dangerous. If a rat bites an electric cord with alternating current it can result in muscle tetany so that the animal is unable to let go of the cord. In addition, the muscle tetany can result in the rat experiencing cardiac arrhythmias or arrest, as well as, respiratory arrest.

Inhalation injury due to smoke can cause edema to the upper airway resulting in obstruction, tissue damage, congestion, and respiratory failure.

The extent or severity of burn injuries will vary depending on the type, duration, and intensity of exposure to the burn agent and the area of the body involved.

The prognosis for burns depends on several factors:

Amount of tissue burned
Degree of burn
Areas of the body affected
Complications (e.g., infection) may develop
General health of rat

Complications such as: pulmonary edema, pneumonia, tissue sloughing, gangrene, nephritis, and neurological impairments can play a factor in the overall prognosis.

Minor burns generally have a good prognosis. However, with extensive and severe burns the prognosis may be grave. Your veterinarian can help evaluate whether the burns are treatable or if euthanasia needs to be considered.

Figure

Burn Case History

Fig. 1: Electrical burn in a 10.5-month-old female rat (Scampers)

First Aid (care prior to transport to the veterinarian)

Remove pet rat from the source of the burn. If the source is electricity be careful with removal. Attempt to shut off power to source. If this is not feasible then use a non-conducting object like a wooden spoon, rug, or rubber mat to gently move the rat away from the source.
If the rat is unconscious check for foreign objects in the mouth and remove if visible. Check for signs of breathing by watching for rise and fall of chest. If the rat is not breathing the following techniques may be tried to restore breathing:
1. Very firmly massage or rub the rat’s chest rapidly.
2. Artificial respiration, if massage is unsuccessful, may be tried. Care must be taken when using the following technique so as not to blow so forcefully as to damage the rat’s lungs:
  Lay the rat on its back with the head extended only enough to open airway. It is important to have support for the head to prevent cervical (neck) injury. Creating a seal around the rat’s muzzle, blow puffs of air into the rat’s nose so as to see a rise in the chest. Rats normally breathe rapidly so the blowing of puffs of air should be done rapidly. Note: be aware breathing into the rat’s mouth may cause air to enter and bloat the stomach.
Cease or do not use any of these techniques on a rat that is breathing!
In the event the rat has stopped breathing and a heartbeat cannot be detected, begin CPR by alternating two quick mouth-to-muzzle breaths with 30 chest compressions (compressions should be rapid to a rate of 80 to 100 times per minute ²⁹).
Chest compressions can be done by squeezing the chest between the thumb and forefinger for small rats, or by compressing the palms of the hands one on each side of the widest portion of the chest for larger rats. Stop between every 5 cycles of breaths and compressions (5 cycles equals about 2 minutes) to check for breathing and a heartbeat. Continue CPR if heartbeat is not detected and there is no breathing. ²¹^, ²⁹

Cease compressions, vigorous rubbing, or artificial respiration once the rat begins to breathe and/or respond on its own.
Once the rat is stable or conscious check for burn areas. Because rats can quickly become hypothermic when rinsed in cold water, try to gently rinse the burn area or apply a clean cloth rinsed in lukewarm water to the site of the burn to halt the continued burning of tissue.
Wrap the rat in a clean dry towel or cloth to keep warm and transport quickly to a veterinarian for further treatment.

Diagnostics

Obtain history and observations by the owner of the pet rat
Examine rat
Determine mechanism and extent of burn
Assess for potential complications

For more severe or extensive burns

Thoracic x-ray to rule out pulmonary edema.
Obtain and evaluate lab work: PCV, TS, BUN, blood glucose, CBC, urinalysis.
Do ECG if possible.
Do blood pressure by Doppler, if available.
Do Pulse oximetry.

Treatment

The treatment for burns may vary depending on the type and extent. However, certain aspects of care are common to all burns:

Use aseptic technique to keep the burned area clean and prevent infection.
Care for wounds as directed by the veterinarian.
Relieve pain when present.
Prevent dehydration.
Maintain a normal electrolyte balance.
Maintain a normal body temperature.
Maintain nutrition by increasing protein and caloric intake.

Treatment for minor first degree or second degree burns involving small area

Flush burn wounds with tepid water to prevent loss of body heat to the rat, and to stop further burn damage to tissue.
Keep rat warm enough to maintain normal body temperature and see veterinarian for additional treatment.
Do not apply ice to burn as this can cause further damage to burn tissue and lead to loss of body heat in the rat.
Do not break blisters as this could set up an environment for infection.
Do not apply ointments until directed by veterinarian.
Veterinarian may prescribe the application of Silvadene to burn wounds. The use of antibiotic ointments (e.g., Polysporin or Bacitracin) should only be applied if directed to do so by a veterinarian.
Administer analgesics such as ibuprofen, or meloxicam as prescribed by veterinarian.
Administer broad-spectrum antibiotic if infection thought to be a concern.

Treatment for electrical burns

Administer oxygen if required.
Gently flush oral burns with tepid water. Do not break or peel blistered skin.
If pulmonary edema is present give furosemide and administer bronchodilators such as aminophylline, or theophylline, or albuterol.
If shock is present warmed SQ electrolyte crystalloids such as Ringers Lactate may be given. Give cautiously if pulmonary edema is present.
Avoid the use of corticosteroids, such as dexamethasone, unless shock or laryngeal swelling is present.
Administer analgesics.
Apply Sucralfate suspension or Orabase to oral burns.
Initiate a broad-spectrum antibiotic such as trimethoprim/sulfa.
Esophagostomy tube placement may be necessary if burns involve the mouth, and the rat’s normal feeding ability is temporarily impaired, so food and water may be given.

Treating inhalation injury

Provide humidification and oxygen.

Treatment for moderate to severe burns

Administer CPR if necessary.
Wrap rat in clean, soft cloth or bed sheet to maintain warmth.
Seek out emergency veterinary care if primary veterinarian is not available.
*Note: euthanasia needs to be considered if severity of burns precludes comfort and quality of life for the rat.

For information regarding medications refer to the Rat Medication Guide.

Nursing Care

Provide hospital cage during recovery
Provide clean bedding daily such as felt, soft t-shirt type material or ink-free paper towels. Avoid using material such as terry cloth type towels that can ravel. Also avoid litter-type bedding, post-op, until healed to prevent the chance of wound contamination or infection.
Provide additional warmth to maintain body temperature within normal limits. It is essential that the rat does not become overheated or dehydrated. The rat should also be able to move away from the heat source if it becomes uncomfortable. If the rat is unconscious or immobile extreme care must be taken to keep the heat low and stable.
- You can use an isothermic product that is heated in the microwave such as SnuggleSafe®. Make sure to follow the product directions carefully and wrap in a towel before placing in the cage. SnuggleSafe® will provide heat for 12 hours before needing to be reheated. Other similar types of products may vary in re-heat time. Check directions for individual product.
- If using a heating pad (good for long term use) use only the low heat setting, put a thick towel in between the pad and the cage bottom, and place beneath a corner of the cage.
- If none of these options are available you can use a plastic bottle filled with hot water, and wrapped in a towel, in the corner of the cage.
Give topical or oral medications as prescribed by veterinarian.
Clean burn wounds as directed by veterinarian.
Assess nutritional status:
- Provide fluids to prevent dehydration. If the rat is willing to drink on its own or by syringe (using needless syringe), the following are suggested: fresh water, or a glucose mixture of 3 teaspoons of honey in 1 pint of warm water (be sure water is warm enough to dissolve honey and then cooled just enough so as not to burn rat’s mouth), or Jell-O water, or electrolyte replacement drinks such as Pedialyte or Gatorade (which can be found in local grocery stores). Care should be taken to prevent aspiration when giving fluids with an oral syringe. If the rat is not drinking discuss providing warmed SQ fluids with your veterinarian.
- Please note that Pedialyte is only good refrigerated for 24 hours after opened, but can be frozen as ice cubes and thawed as needed.
- Provide additional nutritional supplement, such as soy baby formula, Ensure, Boost, NutriCal paste (for dogs and cats, found in pet store), mashed avocado, pureed foods or baby foods.
- Where oral burns are involved, soft foods will be required until swelling of tissue is resolved and blisters are healed.
- If the rat is not willing to eat on its own, provide feeding in an oral needless syringe every 2 hours, being careful to prevent aspiration. Providing small amounts of food in this fashion will help to promote intestinal motility during illness. Include multi-vitamin supplement (can be found in pet store) if food intake is poor.
See veterinarian if condition worsens and for all follow-up appointments.

Outcome

Vital signs stable
Pain relieved
Burn wounds heal
Nutrition maintained
Weight maintained
Infection prevented
Euthanasia if severity of burns precludes quality of life

Prevention

Burns from scalding water can be prevented by monitoring bath water temperature prior to bathing the rat.
Be cautious when cooking in the kitchen if your rats are free-ranging.
Cover unused electrical outlets with safety plugs. Elevate electrical cords out of reach or place safety plastic cord covers on those that can’t be elevated.
Prevent thermal burns by monitoring use of heating pads or elements during post-op recovery or severe illnesses where a heating pad may be required to maintain the rat’s body temperature.
Rat proof free range areas as you would childproof play areas for children.
Ask vet to dilute caustic medicines before injecting.