Cyanosis in Dogs

By Malcolm Weir, DVM, MSc, MPH; Robin Downing, DVM, DAAPM, DACVSMR, CVPP, CRPP

What is cyanosis?

When there is not enough oxygen being carried to the body by the red blood cells, the skin and mucous membranes (e.g., the gums) can turn a bluish color. This is known as cyanosis. There are several different conditions involving the cardiovascular/circulatory system and/or the respiratory system that can lead to cyanosis. Treatment will depend upon the underlying reason for the low oxygen levels.

What are some causes of cyanosis involving the circulatory system?

Some dogs are born with defects or abnormalities in the structure of the heart and surrounding blood vessels. Blood with low levels of oxygen may be shunted from the right side of the heart to the left, mixing with blood that has high levels of oxygen, which reduces the oxygen level before the blood is pumped out to the rest of the body. These structural abnormalities include patent ductus arteriosus (PDA), ventricular septal defect (VSD), atrial septal defect (ASD), tetralogy of Fallot, abnormal return of blood from the lungs, and abnormal opening of the heart valves.

Some dogs will develop circulatory abnormalities that can lead to cyanosis. These acquired conditions include:

  • degeneration of the heart valves
  • deterioration of the heart muscle itself
  • accumulation of blood or fluid in the sac surrounding the heart (the pericardium)
  • blood clots in the lungs
  • high blood pressure in the lungs (pulmonary hypertension)
  • destruction of the red blood cells by the body’s own immune system (immune mediated hemolytic anemia, or IMHA)
  • shock

What are some of the causes of cyanosis involving the respiratory system?

There are many different abnormalities in the respiratory system that can contribute to cyanosis, since the respiratory system is how oxygen enters the body. These conditions include:

  • paralysis of the larynx
  • collapsing of a section of the trachea
  • abnormal narrowing of the trachea from birth
  • pneumonia
  • asthma
  • lung parasites (worms or flukes)
  • bruising of the lungs from trauma
  • smoke inhalation
  • electrical shock


Are there any other major causes of cyanosis in dogs?

Muscle damage, such as trauma to the diaphragm (the muscle between the chest and abdomen that facilitates breathing) or to the chest wall can interfere with breathing and cause cyanosis.

The nervous system can also interfere with breathing and lead to cyanosis. Nervous system issues that may influence breathing include inflammation of the brain or brainstem, brain trauma, stroke, or a brain tumor. Other nervous system influences on breathing and potential cyanosis include paralysis or poisoning.


Can cyanosis be treated?

The presence of cyanosis means there is an emergency and demands immediate care to stabilize the dog to improve oxygen levels in the blood and tissues.

"Treatment must include managing the underlying problem
that led to cyanosis in the first place."

Treatment must include managing the underlying problem that led to cyanosis in the first place. The root cause of cyanosis in a dog may be life-threatening and may or may not be reversible. Oxygen therapy, removing fluid from the chest (to relieve pressure on the lungs that prevents them from inflating), or creating an opening in the windpipe to facilitate breathing may be needed. Prescribed medications will depend upon the underlying diagnosis, and there may be a need for modified activity or a special diet depending on the underlying cause of the cyanosis.

What kind out outlook can I expect for my dog with cyanosis?

When a dog is hospitalized for cyanosis, the veterinary health care team monitors the situation very closely so they can respond to any changes in the dog’s status quickly.

Once the dog is back at home, monitoring of gum color, breathing rate, and activity/mobility will be important. Homecare will be heavily dependent upon the underlying diagnosis that caused the cyanosis. If primary heart or lung disease is present, the long-term outlook may be very guarded.

It is important to follow homecare instructions very carefully, and to seek veterinary care if something does not seem right.

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