Shock is a condition resulting from a depressed state of many vital body functions caused by a lack of effective circulation. A veterinary textbook on emergency medicine defines shock as “the clinical state resulting from an inadequate supply of oxygen to the tissues or an inability of the tissues to properly use oxygen.” The term ‘shock’ can mean different things to different people, and medical professionals still debate the true meaning of the word. Regardless of cause, shock is life-threatening and requires immediate attention and treatment. If signs of shock are recognized, or a serious injury has taken place, supportive care, such as intravenous (IV) fluids, oxygen and other measures can help reverse shock and prevent permanent organ damage. The key to successful overall treatment is prompt professional care.

Shock and the Cardiovascular System

Circulatory system. Illustration by Isaac Mayo

To gain a basic understanding of shock, one must first have an understanding of the normal cardiovascular system of dogs and cats. Think of the cardiovascular system as a closed circuit consisting of a pump (the heart) and a series of stretchable tubes (blood vessels). The system is filled to capacity with a fluid (blood) that circulates through the tubes delivering fuel (oxygen and other metabolic substances) and picking up trash (carbon dioxide and other metabolic waste). In order to be efficient, the pump must be able to deliver a proper amount of the fluid and there must be enough fluid to completely fill and stretch the system of tubes. An insult to any part of this system that results in lower fuel delivery, excess fuel burning, and/or excess waste accumulation may result in shock and decreased oxygen delivery. 

Causes of Shock

The most common cause of shock in our pets is trauma: e.g., fights with other animals, being hit by a car, and gunshots. Other causes include poisoning, insect stings, fluid loss from vomiting and/or diarrhea, infections, burns, and lack of oxygen caused by heart failure or obstruction of airways (pneumonia or choking, for example). 

Basically, it can be broken down into:

Regardless of the cause, shock is life-threatening. Immediate identification and treatment is crucial.

Signs of Shock

Early Signs of Shock

Late Signs of Shock

What to Do

When the pet is in shock, prevent loss of body heat by covering the patient with blankets or jackets. Illustration by Isaac Mayo

Successful treatment of a patient in shock involves prompt recognition of the signs, immediate initiation of first aid procedures, and safe and rapid transport to a veterinary facility for definitive treatment.

What NOT to Do

Well-meaning pet owners often use first aid procedures that may seem helpful, but, in fact, may prove dangerous to the animal.

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