What is smoke inhalation?
Smoke inhalation injuries can occur with exposure to smoke in large or small quantities. Fires produce a variety of damaging substances, each of which can affect a pet’s airways, lungs, and overall well-being.
Factors that play a role in smoke inhalation include:
- Carbon monoxide. Carbon monoxide is a colorless, odorless gas that is produced in fires. When carbon monoxide is inhaled and enters the bloodstream, it interferes with the body’s ability to deliver oxygen to organs and tissues.
- Hydrogen cyanide. This substance is released when plastic and other synthetic materials burn. Like carbon monoxide, hydrogen cyanide interferes with the body’s usage of oxygen.
- Chemical irritants. Smoke contains a number of chemical irritants. These irritants can trigger airway inflammation and constriction, as well as other lung damage. The irritants found in smoke may vary, depending on the substances that are being burned.
- Thermal injury. The heat contained within smoke can lead to burns within the airways and lungs, triggering severe swelling and inflammation.
What are the signs of smoke inhalation?
Signs of smoke inhalation vary, depending on how much smoke was inhaled, how long the cat remained in smoky conditions, what chemicals were present in the smoke, etc. A pet exposed to small amounts of smoke for a brief period of time will have very different clinical signs than a cat confined in an extremely smoky room for a prolonged period of time.
The most common signs of smoke inhalation are respiratory signs. Affected cats may cough, gag, or stand with their neck extended (as if struggling to take in air). Labored breathing, shortness of breath, increased respiratory rate, and wheezing may also occur.
"The most common signs of smoke inhalation are respiratory signs."
The heat and irritants contained within smoke can also cause significant damage to the eyes. Cats may squint due to pain, the third eyelid may remain up over the eye, and you may also notice inflammation and redness of the eyes (conjunctivitis).
Burns may be seen around the face and muzzle. These burns may blister, or may appear as reddened, inflamed areas. If the nostrils are burned, you may notice nasal discharge or visible blisters within the nostrils.
If the brain is deprived of oxygen due to smoke inhalation, pets may show neurologic signs. Neurologic signs are common with carbon monoxide inhalation. Signs include weakness, ataxia (impaired coordination, or walking as if drunk), seizures, and/or coma. Cats may drool excessively or vomit. Cats with carbon monoxide inhalation also tend to develop cherry red discoloration of the gums.
What tests will my veterinarian perform on my pet?
Your veterinarian will probably begin with pulse oximetry, bloodwork, and radiographs (X-rays) of the chest.
A pulse oximeter is a device that is used to assess your pet’s blood oxygenation. This helps to determine how efficiently your cat’s lungs are working and how effectively your cat is delivering oxygen to her organs and tissues. Pulse oximetry may be ineffective however, in cases of carbon monoxide exposure.
Bloodwork abnormalities can help your veterinarian determine the severity your pet’s lung injuries. Bloodwork findings can guide treatment decisions for your pet, while also providing information to better predict your pet’s prognosis.
Radiographs (X-rays) allow your veterinarian to determine the extent of lung damage that has occurred. In most cases, these changes are visible immediately. In many cases however, these changes will continue to progress over 48-72 hours after the initial injury. Radiographs are often repeated several times during the first 72 hours of treatment, providing a way for your veterinarian to monitor your pet’s lung damage and adjust treatment as needed.
An electrocardiogram (ECG) may also be performed, to assess your pet’s heart rate and rhythm. Oxygen deprivation can lead to heart damage, which may be detected using the ECG.
The heat associated with smoke inhalation and fires often results in ulceration of the eyes. Therefore, your veterinarian may perform a corneal stain or other ophthalmologic tests to assess your cat’s eyes and rule out injuries such as corneal ulceration.
How is smoke inhalation treated?
The treatment of smoke inhalation depends upon the severity of your cat’s signs. In most cases, the injuries seen with smoke inhalation progress over 48-72 hours; therefore, you can expect that your cat will probably be hospitalized and monitored for at least 72 hours.
In the early stages, most cases of smoke inhalation are treated with oxygen therapy. Oxygen clears carbon monoxide from the bloodstream, improving oxygen delivery to the body’s tissues. Your cat may be placed in an oxygen cage, where concentrated oxygen can be delivered in a way that is non-stressful. If your veterinarian does not have an oxygen cage, they may administer oxygen via facemask or 'flow-by' oxygen (holding an oxygen tube near your cat’s face). If your cat has extreme upper airway swelling that prevents breathing, your veterinarian may need to place a tracheotomy tube (breathing tube inserted through the trachea) to administer oxygen.
Your veterinarian will also likely place an intravenous (IV) catheter in your cat. This catheter allows IV fluids to be administered, in order to keep the lungs moist and decrease the risk of complications. Additionally, your cat may be unwilling or unable to drink water for the first few days after smoke inhalation, so IV fluids can be used to prevent dehydration.
Smoke inhalation often results in painful burns, so your veterinarian will also administer pain medication to your cat. Affected cats are typically given injectable pain medications to keep them comfortable. Oral anesthetic rinses may also be used, if burns within the mouth are present.
"Smoke inhalation often results in painful burns, so your veterinarian will also administer pain medication to your cat."
Your cat may also receive bronchodilators to help keep his airways open if needed. In some cases, antibiotics may be required to treat secondary infections that can occur following lung damage.
In some cases, cats may require additional supportive care, such as nebulization and coupage. These techniques can be used to deliver medication directly to the lungs and to remove lung secretions. See handout "Techniques for Nebulization and Coupage in Cats" for more information on these techniques.
What is the prognosis with smoke inhalation?
Most cats with smoke inhalation have a good prognosis. Estimated survival rates for animals without skin burns are approximately 90%, according to multiple studies.
Cats that present with neurologic signs, extensive skin burns, or whose condition deteriorates on the second day of hospitalization typically experience worse outcomes. The prognosis is guarded for these patients.