Carbon Monoxide 


Carbon monoxide is ‘the silent killer. It is a tasteless, colourless and odourless gas that can quickly lead to sickness and even death, in dogs or people.


Carbon monoxide bonds with the haemoglobin in red blood cells and has 6 times higher affinity than oxygen. Hence it competes with oxygen and wins every time. Consequently the blood loses oxygen and the body’s cells begin to suffer and die.


Small animals with less lung capacity are more sensitive to high levels of carbon monoxide than larger animals or humans.


Birds are particularly susceptible and often show signs first.


In fact, your pet becoming ill may be the first indication there is a problem, so knowing the symptoms in your dog and other pets is vitally important.


Always investigate a carbon monoxide leak if your pet becomes lethargic, behaves out of character or ill, particularly if this coincides with putting the heating on, using a gas fire or some other appliance.  If your pet dies unexpectedly and suddenly in circumstances not related to their age or an existing health issue, you should immediately consider carbon monoxide as a possible culprit and ensure you protect yourself and other animals.


Read on to learn more about carbon monoxide, including how to stay safe so you can protect your dog and other pets, and keep yourself and your family safe too.


What is it?


Carbon monoxide poison is a natural by-product of fuel combustion present in car exhaust and improperly vented furnaces, space heaters, water heaters, fireplaces, and even tobacco smoke.


Usually carbon monoxide gas is safely carried outside the home by means of the chimney, extractor fan or flue. However faulty or badly fitted appliances can allow the noxious gas to escape into our living and sleeping areas. If the rooms are poorly ventilated levels of the poisonous gas get higher and more dangerous. Yet even lower levels of carbon monoxide can build up within the bloodstream over time, causing a toxicity known as carbon monoxide poisoning. Prolonged exposure to carbon monoxide will eventually lead to death.



Common causes of carbon monoxide poisoning in dogs and cats


Most cases of carbon monoxide poisoning in animals occur as a result of human error. For example a dog left in closed garage with car engine running can receive toxic levels of carbon monoxide in about ten minutes.


Pets left in a running car that has a blocked exhaust pipe have died in just 15 minutes from carbon monoxide poisoning inside the car.


Poisonous carbon monoxide fumes exist the cargo space of aeroplanes which is also a risk to pets.



Other potential sources of poisoning for pets


Other sources of dangerous levels of carbon monoxide gas can include: barbecue grills, gas fireplaces, gas water heaters, paraffin lamps or heaters, ovens, propane space heaters, furnaces and camping stoves.



Poisoned pets


Affected pets act in the same confused and lethargic way that affected humans do. If your usually energetic pet doesn’t want to play, yet revives after being outdoors for a while, that could indicate a potential poisoning problem.


If you notice any change in your pet’s behaviour (or your own health) that coincides with cold weather or putting the heating on, check your appliances and don’t assume it’s a seasonal illness.




A distinctive sign common to both people and pets are particularly red gums in the mouth. Other symptoms of carbon monoxide poisoning include one or more of the following:


  • Drowsiness
  • Weakness
  • Red lips, ears, and gums
  • Lack of co-ordination
  • Difficulty breathing
  • Exhaustion and not wishing to exercise
  • Nausea
  • Vomiting
  • Collapse




If you suspect that your dog has been exposed to carbon monoxide:

  • immediately call the vet
  • remove your dog to a location where they can breathe fresh air and take them to the vet
  •  stop using all appliances and switch them off.
  •  open doors and windows to ventilate the property
  •  evacuate the property immediately
  •  call the gas emergency number on 0800 111 999 to report the incident, or the (HSE) Gas Safety Advice Line on 0800 300 363
  •   don’t return to the property until it has been checked





The goal of treatment for carbon monoxide poisoning is to re-oxygenate the blood as quickly as possible.


Oxygen therapy – using a breathing mask or oxygen chamber your vet will begin oxygen therapy immediately.


Intravenous fluids – oxygen deprivation makes the blood more acidic.

Intravenous fluid therapy helps bring the blood pH back to normal levels.


Respiratory support – in some cases you may need a ventilator to bring a pet to a stable condition over a longer period of time.





If you treat mild cases early, the pet should make a full recovery.


Depending on the severity of carbon monoxide poisoning, your pet may need to go to hospital until symptoms reside and blood oxygen levels return to normal.


In cases of prolonged exposure to carbon monoxide gas, or in cases of severe poisoning, the pet may suffer long-term side effects to the brain.



Going forward


Limit your pet’s activity for at least six weeks.

Replace long walks with short ones and reduce playtimes until recovery is complete.

Keep your dog calm and relaxed and offer extra reassurance.

You may see nervous symptoms in affected pets weeks after they seem to recover.

Rest, a healthy diet and plenty of water can support recovery.

Monitor your dog for recurrence of symptoms.

If you are unsure about anything, call your vet for advice.



Carbon monoxide detector



To prevent possible or re-occurring episodes


  • experts  should annually check all fuel burning devices


  • chimneys and flues should be swept at least once a year


  • get carbon monoxide detectors fitted and serviced regularly. These will alert you to a leak. Make sure it’s approved to the latest British or European Standard (BS Kitemark or EN50291)




Further reading: to read our other article on carbon monoxide poisoning, what to do if you suspect carbon monoxide poisoning in humans and what you can do to prevent it, click here.



First Aid for Pets provides this information for guidance and it is not in any way a substitute for veterinary advice. The author does not accept any liability or responsibility for any inaccuracies or for any mistreatment or misdiagnosis of any person or animal, however caused. It is strongly advised that you attend a practical First Aid for Pets course or take our online course to understand what to do in a medical emergency.

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