Carbon Monoxide Poisoning in Cats

What is carbon monoxide?

Carbon monoxide (CO) is a colorless, odorless, tasteless gas that is produced during the burning of fossil fuels, such as natural gas, propane, wood, and oil. It causes poisoning by binding to hemoglobin, which is the molecule in red blood cells that carries oxygen around the body.

Carbon monoxide binds more easily to hemoglobin than oxygen does, so it will gradually displace oxygen in the blood. Over time, blood oxygen levels drop (hypoxemia) and the body becomes deprived of this vital nutrient. All organ systems in the body need oxygen to function. 

If carbon monoxide builds up in your home, garage, or other enclosed space it can be extremely dangerous for you, your family, and your cat.

How does carbon monoxide poisoning occur?

Poisoning occurs from breathing in excessive levels of carbon monoxide. Common sources include malfunctioning gas stoves, furnaces, or other devices that burn fossil fuels, such as generators and cars. 

Improper ventilation can also cause poisoning. For example, running a car in an enclosed space is extremely dangerous and can have devastating consequences. Blocked chimneys and blocked car exhaust pipes can cause carbon monoxide buildup, as can running outdoor fuel-burning stoves or generators indoors.

Smoke inhalation is another potential cause. Carbon monoxide is one of several dangerous substances present in smoke. Any cat with history of exposure to residential fires or wildfires is considered at risk.

Compared to humans, cats are smaller, breathe faster, and spend more time indoors, so they are at higher risk of carbon monoxide poisoning and may show symptoms earlier. 

What are the clinical signs of carbon monoxide poisoning?

Symptoms of carbon monoxide poisoning are consistent with low oxygen levels in the body. Symptoms vary depending on severity and length of exposure. 

• Early signs include dizziness, weakness, nausea, sleepiness, and rapid breathing. 
• Cats may appear confused, agitated, or disoriented. 
• Bright cherry-red gums and ears may be noted.
• More severe signs include seizures, collapse, and loss of consciousness. 
• If left untreated, death can occur. 

Unfortunately, even with treatment, death can result in severe cases. If you suspect your pet has carbon monoxide poisoning, it is important to immediately contact your veterinarian or Pet Poison Helpline, a 24/7 pet poison center, at 1-800-213-6680 to help determine the risk of poisoning to your pet.

How is carbon monoxide poisoning treated?

Take these initial steps immediately:

• Move all cats and people to fresh air.
• Contact emergency services in your area and seek medical care.
• If it is safe to do so, shut off any fuel-burning appliances and open doors and windows.
• Call your veterinarian. If they cannot see your cat right away, you may need to contact local emergency veterinary clinics and Pet Poison Helpline. 

Once at the veterinarian, your cat will be assessed. Mildly affected cats may improve with fresh air only. For more severely affected cats, 100% oxygen therapy will be initiated. This will eventually displace the carbon monoxide from the hemoglobin.  True antidotes are available for severely affected cats.

If smoke inhalation is the cause, then other symptoms may be present, such as burns and airway damage from heat or other chemicals. Your cat should be bathed to remove any smoke residue as soon as it is safe to do so and may need additional treatment such as wound care.

How is carbon monoxide poisoning prevented?

• Working carbon monoxide and smoke detectors are vital in any home. Check them regularly and change the batteries if they are not hard-wired in.
• Have all fossil-fuel-burning appliances, such as stoves, furnaces, fireplaces, and generators serviced regularly.
• Ensure ventilation pipes and chimneys do not become blocked with snow, ice, or debris.
• Do not operate outdoor heating or cooking appliances indoors. 
• If running a vehicle in an enclosed space such as a garage, ensure doors are open and it is well ventilated.

What is the prognosis for carbon monoxide poisoning?

If carbon monoxide poisoning is caught early and symptoms are mild, the prognosis is good for full recovery. A gradual reintroduction to exercise and normal activity level will be needed for more severe cases.

Pet Poison Helpline, an animal poison center based out of Minneapolis, MN, is available 24/7 for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals, and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s per-incident fee includes follow-up consultations for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com.