Carbon Monoxide Poisoning in Dogs

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3 min read

Key takeaways

Carbon monoxide (CO) poisoning in dogs results from excessive exposure to CO gas.

  • The presentation of CO poisoning varies depending on severity and progresses from weakness and breathing difficulties with bright red gums, to coma and death
  • Investigation involves physical examination and blood work including measurement of blood levels of carboxyhemoglobin
  • Treatment involves removing the dog from the source of CO, oxygen supplementation, correction of blood acid levels, and medication to treat secondary symptoms such as seizures
  • Prognosis depends on the extent of toxicity
  • Mild cases improve rapidly with nothing more than removal from the source and fresh air
  • Severe cases can be fatal
  • Dogs with suspected exposure to CO gas require emergency veterinary treatment
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A closer look: Carbon Monoxide Poisoning in Dogs

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas and is a product of incomplete combustion and builds up due to poorly functioning oil, gas, and wood-burning appliances. Dogs may also be exposed when left in a car in an enclosed space with the engine running. CO enters the bloodstream, displaces the oxygen in the red blood cells and triggers hypoxemia (insufficient oxygenation of the blood). Dogs with suspected exposure to CO gas require emergency veterinary treatment.

CO poisoning is an uncommon condition with a variety of presentations. Low level CO exposure results in mild symptoms and responds well to treatment whereas severe CO exposure is an emergency condition.

Carbon monoxide poisoning in pets is primarily a concern because humans are likely to be exposed along with their pets.

Risk factors

Symptoms can vary depending on the severity and duration of exposure. Dogs with low grade, chronic exposure to CO gas present with less severe symptoms such as vomiting, lethargy, and exercise intolerance. Dogs with severe, acute exposure are more likely to present with breathing difficulties, seizures, vision or hearing defects, coma, or death. People in the same environment as an affected dog are also likely to be affected.

Possible causes

Common means of exposure to CO include dogs kept in a car, in an enclosed space, with the engine running, faulty gas and oil fuel burners in furnaces and water heaters, blocked chimneys, and house fires.

Main symptoms

Testing and diagnosis

Investigation of CO poisoning in dogs involves:

  • Physical examination
  • Blood work (measurement of carboxyhemoglobin levels in the blood)

Steps to Recovery

Treatment of CO poisoning includes:

  • Being moved to fresh air
  • Oxygen supplementation
  • Fluid therapy
  • Symptomatic medication (Anti-seizure medication)

Prognosis following CO poisoning varies significantly. Mild cases that are quickly removed from the source of CO gas normally recover completely without treatment. Severe, prolonged exposure is often fatal and cases that survive require extensive rehabilitation such as exercise management and seizure treatment. Some cases of blindness or deafness are irreversible.


Prevention involves vigilance regarding possible hazard:

  • Regular servicing of chimneys and gas or oil fuel-burning appliances.
  • Turning off the engine in enclosed spaces
  • Installing CO detectors

Is Carbon Monoxide Poisoning in Dogs common?

Carbon monoxide poisoning is uncommon in dogs.

Typical Treatment

Treatment of CO poisoning includes:

  • Oxygen supplementation
  • Fluid therapy
  • Symptomatic medication (Anti-seizure medication)


PetMD Editorial - Writing for PetMD
Graham Bilbrough MA VetMB CVA MRCVS - Writing for Vetlexicon

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