Low Blood Oxygen in Cats

Low blood oxygen is a condition in which the oxygen saturation in the cat’s blood drops below acceptable levels. The medical term for low blood oxygen is hypoxemia, hypoxia, or anoxia. Lack of oxygen in the blood can cause anemia and lead to respiratory or cardiac failure. Lack of oxygen in the blood can also cause severe neurological problems and result in the brain shutting down other bodily systems to reroute available oxygen to the brain. Low blood oxygen is commonly caused by respiratory problems, but other underlying conditions can cause it as well. As blood oxygen levels drop, life-threatening conditions including coma and cardiac arrest can result in death. Any animal exhibiting signs of low blood oxygen should be seen by a medical professional as soon as possible.

A cat suffering from low blood oxygen will exhibit several symptoms, most of which closely mimic symptoms associated with trouble breathing or oxygen deprivation. These symptoms will grow more severe as the blood oxygen level decreases. Generally, symptoms will begin with signs of breathing trouble and progress to include marked weakness and eventually fainting or, in very severe cases, coma or death.

Symptoms include:

• Lethargy
• Weakness
• Trouble breathing
• Rapid breathing or panting
• Breathing through the mouth 
• Breathing accompanied by extreme chest or side movements
• Exercise intolerance
• Bluish tint to gums, skin, or mucous membranes
• Lack of appetite
• Pain and associated vocalizations
• Depression
• Fainting or collapse
• Heart failure
• Coma
• Death

Low blood oxygen in cats is caused by one of three primary factors. Either there is a reduced ability for blood cells to carry oxygen, an issue with lung performance, or an inability of the tissues in the body to absorb and use the available oxygen. The most common underlying cause of low blood oxygen is a respiratory issue. Causes of low blood oxygen include:

• Respiratory disease
• Pneumonia
• Bacterial infections of the lung
• Asthma
• Fluid in the chest cavity
• Congestive heart failure
• Injury or trauma
• Damage to the airway
• Heart disease
• Kidney disease
• Head injuries
• Some cancers, commonly lymphoma
• Feline immunodeficiency virus
• Parasites like heartworms or lungworms
• Anesthesia
• Poisoning or toxicity
• Histoplasmosis, caused by inhalation of a fungus found around chickens

Identifying if low blood oxygen is the cause of your pet’s symptoms is only the first step in properly diagnosing the cat’s condition. Low blood oxygen is often a symptom of another underlying cause, and correctly diagnosing that issue is essential for successful treatment. Be prepared to provide your cat’s medical history, describe their symptoms, and discuss any recent issues or treatments that might have caused blood oxygen levels to fall below normal. Your veterinarian will begin with a full physical exam. They will measure the oxygen saturation in your cat’s blood using non-invasive methods like pulse oximetry or more invasive methods that help identify arterial blood gasses. 

Other diagnostic methods that are commonly employed to search for underlying issues or signs of infection will also be used. A blood sample will also likely be drawn and analyzed for a complete blood count, biochemistry panel, and electrolyte panel. If heart issues are observed, an electrocardiogram may be used to monitor the cat’s heart function. X-rays and other imaging techniques will also likely be used to look at the lungs and chest cavity for signs of infection, fluid build-up, parasitic activity, and tumors. These imaging techniques will also be used to monitor the lungs and heart for proper function. 

Depending on the severity of your pet’s distress when brought in for medical attention, your veterinarian may decide to begin treatment before attempting to diagnose the underlying cause of the low oxygen levels. Early treatment will be focused on bringing the animal’s blood oxygen level up as quickly as possible. The veterinary staff will take care to reduce any stress your animal may be feeling so they remain calm, as this will improve their response to treatments. The full course of treatment prescribed by your veterinarian may vary depending on the diagnosed cause of their condition. Common treatments include:

Oxygen Therapy 

This treatment will be used in all cases of low blood oxygen. Oxygen may be provided using tubing, a mask, or an oxygen cage. Oxygen will continue to be administered while your pet is hospitalized or until blood oxygen levels are raised to within a normal range. This therapy carries a very low risk. 

Steroids 

Steroidal medications will be prescribed if asthma or other respiratory conditions are to blame for your pet’s condition. This treatment may be continued at home after your pet is released from medical care. Proper dosing is essential to minimize the potential for side effects. 

Fluid Drainage 

If the cat’s lungs or chest cavity are filling with fluid, drainage may be required. This is a more invasive procedure and carries a moderate risk. An incision will be made, and tubing may be inserted to drain the fluid. Your pet will require monitoring by veterinary staff while the procedure is being performed. 

Antibiotics 

This category of drug is used if an infection is identified as the underlying cause. This treatment may be continued for several weeks to ensure that the bacteria causing the issue have successfully been eliminated. Proper dosing is essential to reduce the risk of side effects. 

Your pet’s prognosis for recovery will vary depending on the underlying cause of low blood oxygen levels. In cases which the diagnosed cause is treatable, the prognosis is generally good. If your pet is determined to have a chronic condition, like asthma, long-term treatments may be necessary to prevent blood oxygen levels from dropping in the future. Once your pet is released from medical care, carefully monitor for signs of worsening or recurring symptoms. Follow all of your veterinarian’s discharge instructions, including proper dosing of medications and returning for any requested follow-up visits. Reduce stress to your pet while during recovery by avoiding any major changes to their living environment and limiting their movements.