Key takeaways
Cyanosis is described as the blue or grayish discoloration of skin and mucous membranes due to lack of oxygenation. The most noticeable symptom of cyanosis in horses is bluish discoloration of the gums, outer ear (pinna), and genital regions.
- Cyanosis can result from several different underlying conditions, particularly circulatory and respiratory abnormalities
- Cyanosis can be either central or peripheral. The former occurs when all of the animal's tissues are affected by a lack of sufficient oxygen
- Peripheral cyanosis is localized and occurs despite oxygen levels being in the normal range, due to diminished blood flow to a single area of the body
- Cyanosis must always be considered a medical emergency
- The first step in treatment is stabilization, and subsequent treatment options vary in accordance with the underlying condition
- Prognosis is highly dependent on the underlying cause
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A closer look: Cyanosis in Horses
Oxygen is used by the body’s cells to perform all of its basic functions. Blood is responsible for carrying oxygen throughout the body. When blood has sufficient levels of oxygen to support bodily functions, it appears red. As oxygen is removed from the blood by the body, the color of blood changes from red to blue until it travels back to the lungs where oxygen levels are replenished by breathing.
If blood does not receive sufficient oxygen supply, or if it is unable to flow back to the lungs for replenishment, tissues throughout the body start to turn blue as the blood changes color. This color change is most evident where skin is thin and there are high concentrations of blood vessels close to the surface of the skin, such as the gums, extremities, genitals, and outer ears. This phenomenon is referred to as cyanosis.
Cyanosis is an emergency, and immediate veterinary attention is paramount. Many causes of cyanosis are immediately life-threatening, and can result in death if not treated appropriately.
Possible causes
Blue or purple discoloration of skin and mucous membranes, such as the gums, is caused by poor oxygenation. Generally, poor oxygenation is related to heart and/or lung dysfunction. Localized deoxygenation can occur if blood vessels are restricted, such as by traumatic injury or vascular congestion. There are several conditions that can lead to cyanosis.
Risk factors
There are two types of cyanosis:
Central cyanosis affects all the animal's tissues. It is caused by the decrease of oxygenated blood in the body as a result of heart or lung problems.
Peripheral cyanosis is a localized discoloration affecting a particular region of the body. Peripheral cyanosis is caused by obstructed blood flow to a specific area of the body due to vasoconstriction, thrombosis, or heart failure.
Testing and diagnosis
Before diagnostics begin, a horse with cyanosis must be stabilized. Animals presenting with cyanosis typically require supplemental oxygen. Once stabilized, diagnostics include
- Physical examination
- Arterial blood gas analysis
- Diagnostic imaging, including ultrasound
- Bloodwork
- Colic work-up, include rectal examination and nasogastric intubation
Note: nasogastric intubation should only be performed by a veterinarian. There is no safe way to intubate a horse at home.
Treatment of cyanosis is dependent on the underlying cause, and may include:
- Blood transfusions
- Blood thinners
- Removal of fluid from the lungs
- Antibiotics
- Surgery
- Removal of a foreign body, in the case of airway obstruction
Similar symptoms
Horses’ gums are usually pale pink, and the normal color of the gums can vary between horses. Examining a horse’s gums when they are healthy provides the best baseline for identifying cyanosis in the future.
Associated symptoms
Depending on the underlying cause, a number of other symptoms can be commonly seen in association with cyanosis.
