What is cyanosis?
Cyanosis is defined as a bluish discoloration of the skin and mucous membranes of the body (e.g., the gums), caused by inadequate oxygen levels. There are several conditions involving the cardiovascular/circulatory system and/or the respiratory system that can lead to cyanosis. Treatment depends on the underlying reason for 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 oxygen levels may be shunted from the right side of the heart to the left, mixing with blood that has high levels of oxygen. This mixing reduces oxygen levels 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
- 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 causes of cyanosis involving the respiratory system?
There are many different abnormalities in the respiratory system that can contribute to cyanosis, since oxygen enters the body through the respiratory system. These conditions include:
- paralysis of the larynx
- collapsing of a section of the trachea (windpipe)
- obstruction in the trachea
- abnormal narrowing of the trachea from birth
- cancer and/or masses in the lungs
- 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 chest wall or the diaphragm (the muscle between the chest and abdomen that facilitates breathing) can interfere with breathing and cause cyanosis. The nervous system can also interfere with breathing and lead to cyanosis. Nervous system issues that may affect breathing include inflammation of the brain or brainstem, brain trauma, stroke, or a brain tumor. Poisoning and hypothermia are also possible causes of cyanosis in dogs.
Can cyanosis be treated?
The presence of cyanosis means there is an emergency. Immediate care is needed to stabilize the dog and to improve oxygen levels in the blood and tissues. Treatment of cyanosis must include managing the underlying problem that led to cyanosis. 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 on the underlying diagnosis, and there may be a need for modified activity or a special diet, depending on the underlying cause of cyanosis.
What kind of outlook can I expect for my dog with cyanosis?
When a dog is hospitalized for cyanosis, the veterinary health care team monitors the situation closely so they can quickly respond to any changes in the dog’s status.
Once the dog is back at home, it will be important to monitor gum color, breathing rate, and activity/mobility. Homecare will depend heavily on the underlying diagnosis. If primary heart or lung disease is present, the long-term outlook may be very guarded.
It is important to follow homecare instructions carefully and to seek veterinary care if something does not seem right.
