Smoke Inhalation in Cats

Overview of Smoke Inhalation in Cats

Smoke inhalation injury is direct damage to the airways and lung tissue caused by exposure to heat, particulate matter in smoke and the gaseous by-products of fire.

Smoke inhalation injury can be caused by:

• Thermal (heat induced) injury to the upper airways
• Inhalation of particulate matter that settles in upper airways and the lungs
• Asphyxia (suffocation) since the fire reduces the oxygen content in the air that is breathed
• Chemical injury, due to chemicals such as carbon monoxide, cyanide, acrolein, hydrogen chloride and aldehydes that are released as gases within the fire

Smoke inhalation injury can lead to bronchospasm and bronchoconstriction (spasm and constriction of the airways), carbon monoxide poisoning, pulmonary edema (accumulation of fluid in the lungs), acute respiratory distress (inability to breathe) and pneumonia. Smoke inhalation can be fatal.

What to Watch For

• Bright red mucous membranes (inside of lip and gums)
• Dry, unproductive cough
• Raspy breathing sounds
• Wheezing
• Increased respiratory rate
• Increased effort of breathing
• Irritation of the eyes
• Discharge from the eyes or nose
• Collapse
• Unconsciousness
• Respiratory distress
• Respiratory or cardiac arrest

Diagnosis of Smoke Inhalation in Cats

In addition to a thorough medical history and physical examination your veterinarian may recommend the following diagnostic procedures and/or diagnostic tests:

• Thoracic radiographs (chest X-rays) are done to look for evidence of injury or pneumonia. Multiple X-rays may be required to document changes in the lungs over a several day period.
• Arterial blood gas measurements are taken to determine how well the pet is oxygenating and to determine the need for supplemental oxygen administration.
• Carboxyhemoglobin levels. This blood test is done to measure the level of carbon monoxide poisoning.
• A complete blood count (CBC) measures the white blood cell count to assess for evidence of infection and/or inflammation.
• A biochemistry profile is a blood test that is performed to assess for internal organ damage secondary to smoke inhalation injury or secondary to shock.
• Tracheal wash for cytology and culture. This test is performed to look for evidence of pneumonia and to culture the particular bacteria causing the pneumonia. Based on this information, a specific antibiotic can be chosen to fight the infection.
• A fluorescein stain of the surface of the cornea (surface of the eye) is performed to document ulcers or erosions caused by smoke.

Treatment of Smoke Inhalation in Cats

Treatments may include:

• Administration of supplemental oxygen to aid cats with difficulty breathing
• Placement of an intravenous catheter for administration of medications and intravenous fluids
• Bronchodilators such as terbutalline, albuterol, aminophylline or theophylline
• Nebulization (humidification of the air the patient breathes)
• Pain medication for associated burns
• Mechanical ventilation if the patient is unconscious or shows signs of impending respiratory or cardiac arrest
• Physical therapy for the chest (frequent position changes and coupage)
• Eye medication for eye irritation or ulceration

Home Care

Remove pets from burning buildings and transport to a veterinary hospital as quickly as possible. Do not place your own life at risk by attempting to rescue a pet from a burning building.

If possible, have firefighters or medical personnel at the site of the fire administer oxygen to pets suffering from smoke inhalation injury for 10 to 15 minutes prior to transport. Administering oxygen as soon as possible reduces the amount of carbon monoxide poisoning and may stabilize pets that are at risk of dying prior to reaching the hospital.

In-depth Information on Smoke Inhalation in Cats

Smoke inhalation causes direct damage to the upper airways, which include: the nose, sinuses, oropharynx (back of the mouth), trachea (the windpipe), bronchi, and bronchioles (lower airways) and the lung tissue. Additional damage caused by smoke inhalation include the following:

• Heat from the fire (thermal injury) can burn the airways so that they become dry, irritated and lose their ability to remove particles away from the lower airways. Burns to the airways predispose the patient to infection with bacteria.
• Particulate matter within smoke is deposited in both the upper and lower airways and increases irritation and the risk of infection.
• Gases within fires can cause chemical burns in the upper and lower airways, constriction and spasm of the airways, and poisoning, such as cyanide or carbon monoxide poisoning. Carbon monoxide poisoning is a main component of smoke inhalation injury.
• The combined effects of smoke, heat and gases lead to difficulty breathing, respiratory distress and sometimes death of the patient. Respiratory symptoms may develop immediately after exposure to heat and smoke or may take up to 48 hours before they appear. Pulmonary edema (accumulation of fluid within the lungs) can take 6 to 72 hours to develop. If the patient survives the initial injury, pneumonia can follow (2 to 3 days after initial injury) before complete recovery.

Smoke inhalation injury is usually not confused with other diseases because of the circumstances under which it occurs, for example, the pet is removed from a burning building. Other findings can support a diagnosis of smoke inhalation such as the smell of smoke on the pet’s fur and singed or burned hair and whiskers. However, if it is not clear that smoke inhalation is the cause of the pet’s respiratory difficulty, the following should be considered:

• Pulmonary edema. The accumulation of fluid within the lungs an can result from congestive heart failure, biting through an electric cord or an obstruction in the upper airways.
• Pneumonia. This infection within the lungs can lead to difficulty breathing.
• Pleural effusion. An accumulation of fluid within the chest cavity around the lungs makes it difficult for the lungs to expand when the pet takes a breath. The effusion may be blood, pus, chyle (fluid from the lymphatic system) or may result from diseases such as congestive heart failure or hypoproteinemia (low protein levels in the blood).

Diagnosis In-depth

• Thoracic radiographs (chest X-rays) are taken to identify changes in the lungs, due to smoke inhalation. Chest X-rays may be normal for the first 36 hours so, depending on your pet’s condition, your veterinarian may need to take a series of X-rays to document changes and/or the development of pneumonia over a period of several days.
• An arterial blood gas allows the veterinarian to assess the pet’s oxygenating ability, which is often compromised following smoke inhalation injury. Not only does it help determine the need for oxygen supplementation but may also be helpful in determining the pet’s prognosis. Blood gases also provide information about the blood pH (acidity and alkalinity), which can be altered due to respiratory problems or due to shock. Arterial blood gases are not helpful in determining the extent of carbon monoxide poisoning.
• Carboxyhemoglobin levels, which is the amount of carbon monoxide in the blood stream, may be measured to determine the extent of carbon monoxide poisoning present in a patient as well as prognosis. Carboxyhemoglobin levels can be measured only at certain hospitals because the test requires special equipment. However, inability to perform this test has no impact on the ability of your veterinarian to provide appropriate care for your pet.
• A complete blood count (CBC) may be performed to assess the general condition of a pet and to look for high or low white blood cell counts that may be present with pneumonia.
• A biochemistry profile is a blood screen done to evaluate the kidneys, liver and other internal organs, which may be affected due to lack of oxygen or due to shock.
• A tracheal wash is done if pneumonia is suspected. In this procedure, the patient is sedated and a small amount of a sterile saline solution is flushed down the trachea into the lungs and then retrieved by aspiration through a syringe. This sample is examined with a microscope to look at the cells (cytology) and to look for bacteria. The sample is also submitted for culture to identify the type of bacteria causing the pneumonia and to determine which antibiotic should be chosen. Cultures generally take three days to process.
• A fluorescein stain is performed to look for ulcers on the cornea (surface of the eye). Ulcers are outlined by the green dye and indicate the need for eye medications.

Treatment In-depth

Because many of these patients are experiencing breathing difficulties, the majority of smoke inhalation patients will be placed in an oxygen cage immediately upon presentation to the hospital and prior to a complete physical examination. While your pet is allowed to rest in oxygen, your veterinarian will gather the medical history and then complete the physical examination.

If your pet is in a state of unconsciousness, it may be necessary to place an endotracheal tube (through the mouth into the trachea) and assist the pet to breathe to prevent respiratory or cardiac arrest. If your pet remains unconscious and unable to breathe on his own, mechanical ventilation may be offered, in which a ventilator breathes for the patient. In most instances, however, treatment proceeds at a less frantic pace as follows:

• Administration of supplemental oxygen is an essential part of treatment for smoke inhalation injury because difficulty breathing is the main problem associated with this type of injury. Oxygen may be provided by a tube inserted in the nostril and attached to an oxygen line (nasal oxygen), via a facemask or by placing the pet in an oxygen cage. Oxygen therapy may only be required for a few hours or may be necessary for many days depending on the extent of injury and whether the pet develops pneumonia as a secondary problem.
• Intravenous fluids are administered to correct dehydration and to treat shock if present. The intravenous line can also be used for administration of medications such as bronchodilators or antibiotics.
• Bronchodilators such as terbutaline, albuterol, aminophylline or theophylline are used to dilate the airways, which can be constricted due to irritation from the heat and smoke. Dilation of the airways makes it easier for the pet to breathe.
• Nebulization (humidification of the air breathed by the pet) is provided to help the pet mobilize secretions and particulate matter deposited in the airways toward the mouth to be eliminated when the patient coughs.
• Pain medication is administered to pets with burns on their body.
• Mechanical ventilation may be provided for those patients who breathe with great difficulty despite administration of supplemental oxygen and medications. The patient must be placed under general anesthesia for the duration of time they are on the ventilator. An endotracheal tube is placed and the patient is attached to the ventilator, which breathes for the patient.
• Physical therapy is done to help mobilize secretions and particulate matter in the patient’s lungs and airways. Changing the patient’s position helps with drainage and prevents airways from collapsing. Coupage, or percussion of the chest wall by gently hitting the chest wall with cupped hands, helps loosen secretions and particles that can then be removed by drainage or coughing. Encouraging patients to stand and walk if they are capable is as effective as coupage and frequent position changes.
• Eye medications containing antibiotics are used to provide lubrication for irritated eyes and to treat corneal ulcers.
• Antibiotics are not administered to smoke inhalation patients unless pneumonia is documented. Administration of antibiotics when pneumonia is not present can cause patients to develop resistant infections.

Home Care of Cats with Smoke Inhalation

Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not improve rapidly.

Administer all prescribed medication as directed. Alert your veterinarian if you are experiencing problems treating your pet. Some antibiotics can cause nausea, decreased appetite and diarrhea. If your pet experiences these symptoms while receiving antibiotics, notify your veterinarian. An alternate antibiotic may be available.

Exercise restriction is appropriate for a pet recovering from pneumonia because lung capacity is diminished and pets will tire easily if they attempt to exercise. If your pet has pneumonia, your veterinarian will likely set up a date for repeating chest X-rays after antibiotic administration is complete to ensure the pneumonia has resolved completely.