Cyanosis (Blue Coloration) in Cats


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

  • Purplish/bluish coloration of the tongue, gums, lips, and areas of the skin in which the blood vessels are superficial.
  • Possible purplish/bluish coloration of the foot pads.
  • Diagnosis of Cyanosis in Cats

  • Arterial blood gas measurement
  • Pulse oximetry
  • Other specific tests, depending on the disorder that is causing the cyanosis
  • Treatment of Cyanosis in Cats

    Therapy of cyanosis will depend on what is causing the condition.

  • Congenital heart disease. If the condition is caused by congenital heart disease, the treatment is surgery.
  • Chemical. If a chemical has affected the hemoglobin in such a way that it cannot carry oxygen properly, for example, by inducing the formation of methemoglobin, an abnormal type of hemoglobin that cannot carry oxygen, the treatment involves: elimination of the cause, limiting any tissue injury due to poor oxygenation, and administration of medication (methylene blue; N-acetylcysteine) if necessary.
  • Respiratory Disorder. If a respiratory disorder is the cause of the cyanosis, the underlying respiratory disease must be treated with antibiotics if pneumonia or chronic bronchitis is present, diuretics if fluid is building up in the lungs, thoracocentesis, which is removal of fluid or air from the chest cavity if fluid or air is causing the cyanosis, or supplemental oxygen as necessary.

    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.

  • Home Care

    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.

  • Central cyanosis is a result of the entire systemic blood supply being desaturated. Central cyanosis is due to a decrease in oxygenated blood throughout the systemic circulation. All tissues are affected.
  • Peripheral cyanosis is due to desaturated hemoglobin that may be confined to a specific region of the body, for example, if a blood clot has obstructed blood flow to a particular body part or if a tourniquet has been applied. Peripheral cyanosis implies a purplish coloration in the peripheral tissues (oral mucous membranes, vaginal or penile mucous membranes, paw pads or nail beds, etc). All animals with central cyanosis also have peripheral cyanosis, because the entire bloodstream is desaturated. However, it is possible to have peripheral cyanosis without having central cyanosis, if the cause of the decreased oxygenation is localized to a specific region, such as a blood clot that interrupts the blood supply to a specific limb.

    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:

  • Anything that would cause central cyanosis, with resultant bluish coloration in all peripheral tissues.
  • Hypothermia. The low body temperature constricts the vessels in the skin.
  • Thromboembolism, or a blood clot. The most common situation is a “saddle thrombus” which occurs in cats with heart disease. A blood clot develops in the heart and travels down the aorta where it obstructs the blood supply to both rear legs.)
  • Application of a tourniquet (accidental, deliberate, or malicious)
  • Shock (inadequate blood flow to the tissues)

    Causes of central cyanosis would include:

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