Overview of Cyanosis in Cats
Cyanosis is a bluish or purplish coloration imparted to the skin or mucous membranes due to excessive amounts of poorly oxygenated hemoglobin in the circulation. The causes in cats include certain congenital heart diseases, various respiratory diseases, and exposure to certain chemicals that result in the creation of some abnormal forms of hemoglobin which are incapable of binding oxygen properly.
Cyanosis in cats is usually an alarming clinical symptom for pet owners and for veterinarians.
What To Watch For
Diagnosis of Cyanosis in Cats
Treatment of Cyanosis in Cats
Therapy of cyanosis will depend on what is causing the condition.
Emergency treatment involves making sure that the airway is unobstructed and providing oxygen by: face mask, nasal oxygen tube, oxygen cage, intubation of the trachea.
There is no specific home care for cyanosis. Animals who are suspected to be cyanotic should be evaluated by a veterinarian immediately. Depending on the cause of the cyanosis, your veterinarian will make specific recommendations as warranted.
In-depth Information on Cyanosis (Blue Coloration) in Cats
Cyanosis is the bluish or purplish discoloration of the mucous membranes or skin due to excessive amounts of desaturated (poorly oxygenated) hemoglobin in the blood stream. Oxygenated blood is red. Poorly oxygenated blood is dark blue. The more deoxygenated hemoglobin in the bloodstream the more bluish coloration will be imparted to the tissues.
There are two general “types” of cyanosis: central and peripheral.
In young animals, the most likely cause is a congenital heart disease where poorly oxygenated blood that is returning to the heart erroneously bypasses the lungs and is sent back out into the systemic circulation without picking up more oxygen. This is called “right-to-left shunting” because poorly oxygenated blood from the right side of the heart is shunted to the left side of the heart where it is pumped out into the general circulation.
Any age animal can develop cyanosis secondary to severe pulmonary (lung) disease, such as severe pneumonia, or to diseases that prevent the lungs from expanding properly, such as fluid or air in the chest cavity.
Genetic defects in hemoglobin can alter its ability to carry oxygen, however, these defects are rare in companion animals. Hemoglobin defects are more likely to develop secondary to ingestion of, or exposure to, chemicals and oxidants.
Causes of Cyanosis in Cats
Causes of peripheral cyanosis include:
Causes of central cyanosis would include:
Abnormal hemoglobin (methemoglobin) can result in cyanosis due to chemicals that render the hemoglobin nonfunctional.
Diagnosis In-depth for Cyanosis (Blue Coloration) in Cats
Arterial Blood Gas Measurement in Cats
Arterial blood gas (ABG) is the “gold standard” for evaluating a cyanotic patient. The test involves obtaining an arterial blood sample. For maximal diagnostic value, the ABG should be evaluated while the animal is receiving supplemental 100 percent oxygen. The response to supplemental oxygen can be used to help rule in or rule out certain causes of cyanosis. For example, if there is peripheral cyanosis due to obstruction of blood flow to one or two limbs, giving supplemental oxygen does not raise the amount of oxygen in the arterial blood, and does not resolve the cyanosis.
However, if the cyanosis is due to disease of the lungs (edema, infection), hypoventilation, or ventilation/perfusion mismatch, giving supplemental oxygen will raise the amount of oxygen in the arterial blood, and the cyanosis should resolve. Giving supplemental oxygen to animals who are cyanotic because of an abnormal form of hemoglobin (such as methemoglobin) will not be helpful, because methemoglobin cannot bind oxygen, regardless of how enriched the oxygen supply is.
Pulse Oximetry in Cats
Pulse oximetry is readily available to most practitioners nowadays. It is a noninvasive way to get an idea of the amount of oxygen in the bloodstream. A probe is applied to a fold of skin in the axillary (armpit) or inguinal (groin) area, or the lip or tongue in an anesthetized animal. The major advantage of pulse oximetry is that you get a continuous reading, allowing sequential monitoring in response to supplemental oxygen.
Further Diagnostic Tests
Depending on the cause of the cyanosis, further diagnostic tests may be warranted. For example, if cardiac abnormalities are the cause of the cyanosis, cardiac ultrasound, electrocardiography, or angiocardiography may be necessary. If respiratory diseases are the cause of the cyanosis, various diagnostic tests such as thoracocentesis (removal of fluid or air from the chest cavity), a transtracheal wash, complete blood count, chemistry panel, urinalysis, chest X-rays, thoracic ultrasound, and fecal analysis may be warranted.
One or more of the diagnostic tests described above may be recommended by your veterinarian. In the meantime, treatment of the symptoms might be needed, especially if the problem is severe. The following nonspecific symptomatic treatments may be applicable to some pets with cyanosis. These treatments may reduce the severity of symptoms or provide relief for your pet. However, nonspecific therapy is not a substitute for definite treatment of the underlying disease responsible for your pet’s condition.
Therapy of cyanosis is dependent on understanding the cause of the condition.
Emergency Measures for Treating Cyanosis in Cats
Provide supplemental oxygen. In cases of central cyanosis, a reduced supply of oxygen is to be assumed until it can be disproved and supplemental oxygen is to be provided until the actual cause can be ascertained. Obvious mechanical obstructions to airflow (such as a foreign body in the mouth or throat) are removed and a patent airway is established. Then, oxygen is administered immediately either by face mask, a nasal oxygen tube, an oxygen cage, or endotracheal intubation.
If congenital heart disease is the cause of cyanosis, the treatment may involve surgery to correct the defect.
If respiratory disease is the cause, the treatment is:
If excessive amounts of methemoglobin is the cause of the cyanosis, treatment involves: