Excess carbon dioxide in the blood can be very serious for cats, especially when levels or extremely high or the issue continues for an extended period of time. Proper treatment is essential for cats and other companion animals to recover.

Carbon dioxide is a gas that occurs naturally and is found in various quantities in the air. While oxygen is absorbed in the lungs during inhalation or breathing in, carbon dioxide is expelled during exhalation or breathing out. Carbon dioxide is found in the blood at all times in various forms including, bicarbonate, carbonate, carbamino compounds, dissolved carbon dioxide, and carbonic acid. Elevated levels can be dangerous, resulting in a condition known as hypercapnia or hypoventilation. This condition can result in signs of respiratory distress, impaired mental function, and can cause coma or death if not addressed. Cats that are either very old or young are at an increased risk of developing respiratory issues or ineffectively processing carbon dioxide through normal respiration. It is also possible for the condition to occur during anesthesia, often due to the carbon dioxide absorbent in the anesthesia machine being exhausted. 

When excess carbon dioxide is present in the blood, it can cause both respiratory and neurological issues. Observable symptoms include changes in breathing patterns and indications that the nervous system is not functioning properly. Symptoms may change significantly as the condition worsens. Breathing may start out rapid, however, as the levels of carbon dioxide increase; breathing can become slower and more labored. 

Symptoms Include:

Worsening Symptoms Include:

The amount of carbon dioxide in the blood can be affected if problems with the respiratory system, which includes the lungs, airways, chest cavity, and diaphragm, occur. Numerous issues can arise that affect the respiratory system. The cause of your cat’s elevated carbon dioxide levels could be from one of the following: 

Diagnosing excess carbon dioxide in the blood is a simple procedure. Your veterinarian can monitor your pet’s blood gas carbon dioxide level to confirm if it is within normal range or appears to be elevated. Although it may be a simple process to confirm that excess carbon dioxide is present and is likely the cause of your cat’s symptoms, confirming why the issue is occurring may require additional testing. Until the cause is confirmed and properly treated, your pet may still be at risk of the more serious complications. Be prepared to discuss your pet’s history, especially any circumstances that could cause elevated carbon dioxide levels. The veterinary staff may sample blood, urine, or other fluids to test for various sources of infection. X-rays or other imaging techniques might be required to view the lungs and respiratory system for potential issues. If the blood carbon dioxide levels became elevated while your pet was under anesthesia, your veterinarian might not require other tests to confirm the cause. 

The appropriate treatment for your cat’s condition will depend largely on what is causing the buildup of carbon dioxide in their blood. Until the cause is identified, treatment will be largely symptomatic or based on treating the symptoms. Symptomatic treatments include:

Once the cause has been determined, the veterinary staff will begin with treatments to address the underlying issue. These treatments may include:

Your cat’s prognosis will depend on a variety of factors. If excess carbon dioxide is identified and treated quickly, the prognosis is better. If levels remained high for too long or your pet experienced higher levels of carbon dioxide, some permanent damage may occur. Brain damage is a risk associated with elevated levels. Your pet may require hospitalization for a day or two for monitoring and treatment. Once they return home, you can help their recovery by reducing stress on your pet. Avoid making any major changes to their environment while they are recovering. Keep food, water, and litter easily accessible and continue to monitor your cat for recurrence or worsening of their symptoms. If your pet’s condition was related to inhalation of carbon dioxide or toxins in the home, ensure that these issues have been addressed before reintroducing your cat to the environment.