How is cyanosis diagnosed in dogs? Tips and Tricks

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Cyan is a beautiful color when you see it in the sky on a sunny day, but if you ever notice that your dogs gums have more of a purple or blue tone to them, it may indicate cyanosis, and you should contact or rush to your veterinarian immediately. Not just a color change, cyanosis in dogs is a blue to purple discoloration of the skin or gums due to low oxygenation in these tissues. A number of causes can result in blue skin in dogs, but they all relate to a lowered oxygen level in the blood vessels near the surface of these tissues. Lets take a closer look at this condition.

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
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    What is cyanosis? Cyanosis is a bluish to red-purple tinge of the tissues, seen best in the gums and skin, and typically accompanying respiratory distress (i.e., difficulty breathing). When cyanosis is seen in dogs and cats, it’s an indicator of a severe lack of oxygen in the blood (called hypoxemia). It typically means that hemoglobin in the red blood cells doesn’t have enough oxygen or isn’t able to carry oxygen at all.

    Why is cyanosis difficult to diagnose? There are several factors that may hinder you and your veterinarian from being able to detect physical signs of cyanosis. For example, the red blood cell (RBC) count can affect signs of cyanosis—a pet with severe anemia and a low number of RBCs may never show signs of cyanosis. The lower the hemoglobin concentration in a pet, the more the oxygen levels must fall before cyanosis can be clinically detected. Also, patients with shock, carbon monoxide poisoning, or those with abnormal hemoglobin may not show cyanosis well during a physical exam.

    Keep in mind that just because your pet’s gums are pink, it doesn’t necessarily mean that his oxygen levels are normal. Signs of cyanosis aren’t always seen until end-stage or severe hypoxemia.

    How is cyanosis diagnosed? To find out what’s causing the cyanosis, diagnostic tests may include blood work, chest x-rays, measurements of oxygen levels (e.g., pulse oximetry, arterial blood gases, etc.), electrocardiogram, an ultrasound of the heart (i.e., echocardiogram), a chest tap, and more.

    How is cyanosis treated? Treatment for cyanosis typically includes immediate oxygen therapy along with certain types of medications to aid in breathing: diuretics, antibiotics, or even steroids depending on the underlying cause. The prognosis varies based on what the underlying cause is, but the sooner you get to the veterinarian for treatment, generally, the better the prognosis.

    If you do notice signs of cyanosis in your dog or cat (a bluish to red-purple tinge of the tissues), an immediate trip to the veterinarian is imperative; it means your pet has a life-threatening respiratory problem or hemoglobin problem. Without immediate treatment, cyanosis can be fatal within a few minutes.

    As previously published by Dr. Justine Lee on Pet Health Network. Copyright Justine Lee Veterinary Consulting, LLC.