Carbon Monoxide- How Dogs are Affected

• Once man discovered fire, the issue of being poisoned by pollutants began. One of the most common (and the most fatal) is Carbon Monoxide (CO). The toxic gas is odourless, tasteless, and invisible. It is a highly toxic gas that’s the incomplete combustion of carbon-based fuels such as gasoline. Sources of carbon Monoxide are unventilated kerosene or propane heaters, gasoline engines, automobile exhaust, or fumes from carbon-based fuel heating systems. Some causes of carbon monoxide exposure include accidental enclosure of dog in garage with automobile engine turned on, poorly ventilated areas with any source of carbon monoxide (e.g., fireplace, oven, barbecue grill). Another danger to dogs is being left alone in the car while the engine is running.
•     In an article on the PetMD website it is noted that carbon monoxide affects the ability of the blood to carry oxygen, by attaching itself to the hemoglobin (a protein) in the red blood cell. Once inhaled, CO molecules are attracted to hemoglobin several hundred more times than oxygen. CO then replaces the oxygen attached to the hemoglobin and is carried to the dog’s brain and heart thereby causing damage to the heart, lungs, and brain. The condition of low oxygen levels in the blood is known as hypoxemia.   (PetMD, ©1999-2013 ). The combination of hemoglobin and CO is called Carboxyhemoglobin. (The medical dictionary, 2007 ). In addition to binding to hemoglobin, 10% to 15% of CO attaches to other proteins, especially myoglobin within the heart. Chest pains and myocardial injury can occur with just a mild exposure to CO.  ( Quinn, et al., 2009). In a study published in the Annals of Clinical and laboratory Sciences, LR Goldbaum (et al) noted “Dogs inhaling CO (13 percent in air) for 15 minutes died within 15 minutes to 65 minutes with an average COHb (Carboxyhemoglobin) level of 65 percent”. (Goldbaum, et al., 1976 ) .  In the journal “Environmental Health Perspectives”, DG Penney wrote “Dogs were found to be more resistant to Carboxyhemoglobin than humans. (Penney, 1988). Carboxyhemoglobin can also affect the dog’s Central Nervous System whereby a dog would be too weak to walk, and may not be able to stand at all. Carbon Monoxide poisoning affects the hippocampus in the cerebral cortex causing spatial problems, along with memory loss. Some of the symptoms and behaviors (in dogs) of Carbon Monoxide poisoning are sleepiness, Lethargy, Depression, Seizures, loss of exercise stamina, and many more.
•   If you suspect your dog may have CO poisoning, it is imperative to bring the dog to your Vet immediately. The vet will immediately start the dog on oxygen and begin diagnostic tests. A complete blood count, a biochemistry profile, a urinalysis and other applicable body fluid tests will be performed. The vet will collect blood samples for determination of carboxyhemoglobin levels. Obtaining the levels of carbon monoxide in the blood is the most useful test for putting together the initial treatment plan. Treatment will include 100% oxygen and plenty of fluids to improve the flow of blood through the body tissues to areas such as the brain. If you Vet does not have the facilities to treat your dog for carbon monoxide poisoning, you can bring your dog to the local hospital. Long-term treatment will include limiting the activity of the dog such as short walks in lieu of longer walks and running. Observation is important to watch for signs of nervous symptoms, awkward gait and movement and other abnormal behaviors. Usually once the dog is removed from the affected area, the carboxyhemoglobin levels (the dog’s blood) will begin to lower just as fast as they rose.
• Philip K Greis

Works Cited

Quinn, D. K., McGahee, S. M. & Stern, T. A., 2009. Complications of Carbon Monoxide Poisoning: A Case Discussion and Review of the Literature. Primary Care Companion to The Journal of Clinical Psychiatry, 2(11), p. 74–79.

Goldbaum, L. R., Orellano , T. & Dergal , E., 1976 . Mechanism of the toxic action of carbon monoxide. Annals of Clinical and Labratory Sciences, VI(IV), pp. 372-376.

Penney, D., 1988. Hemodynamic response to carbon monoxide. Environmental Health prospectives, Volume 77, pp. 121-130.

PetMD, ©1999-2013 . Carbon Monoxide Poisoning in Dogs. [Online]
Available at: http://www.petmd.com/dog/conditions/respiratory/c_dg_carbon_monoxide_toxicosis#.Uc-8xqLD8zs
[Accessed 30 June 2013].

The medical dictionary, 2007 . carboxyhemoglobin. [Online]
Available at: http://medical-dictionary.thefreedictionary.com/carboxyhemoglobin
[Accessed 30 June 2013].