Shock – how to recognize the signs

The term ‘Shock’ covers a wide range of different conditions that result in a failure of the body to continue its essential functions. This is a true emergency and early recognition and rapid treatment is key to improving survival.

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Shock is defined as an inability of the cells to produce sufficient energy to function. This usually happens because, for some reason, oxygen supply to the body tissues is reduced.

Oxygen is carried from the lungs to the tissues by the red blood cells within the circulatory system. Conditions that affect either the red blood cells, the blood circulation or the amount of oxygen available within the blood stream can result in the development of shock.

Shock can be classified according to the underlying cause:

Hypovolemic shock

Hypovolemia literally means a low blood volume. In this form of shock there has been a loss of blood circulating within the body. This is commonly seen in animals that are bleeding, either internally or externally. Most common causes are traumatic events like road traffic accidents, gunshot injuries, a fall from a height or due to a problem with the blood clotting system. It can also be seen in animals that have lost a large amount of body fluids rather than blood (ie animals with profuse vomiting and diarrhea or extensive burn injuries).

Cardiogenic shock

In cardiogenic shock there is an underlying problem with heart function. There is poor circulation due to the heart not pumping the blood through the body effectively. Typical examples are animals with severe heart disease or with very irregular heart rhythm.

Distributive shock

Distributive shock means that there is the correct volume of blood, but it is not correctly distributed throughout the body. It usually occurs due to an abnormal dilation of the blood vessels. Rather than the blood flowing normally through the body and back to the heart and the lungs where it can get oxygenated again, it tends to ‘pool’ in the blood vessels. This type of shock is typically seen in anaphylaxis (ie severe allergic reactions), excessive heat exposure (ie ‘heat stroke’) or in severe infections that result in sepsis and septic shock (ie pyometra or womb infection in queens or an abscess which may be deep inside the body).

Obstructive shock

As the term indicates, this type of shock occurs due to an obstruction that prevents the normal blood flow to or from the heart. This could be a blood clot within a vessel or external compression of the vessel such as a severely bloated stomach that presses on big abdominal veins or fluid accumulation in the chest that compressing the heart or vessels in the lungs.

Hypoxemic shock

Hypoxia means that there isn’t enough oxygen in the blood stream to be delivered to the tissues. This can occur either because the oxygen is not being delivered to the blood through the lungs, ie severe lung disease, such as pneumonia is present; the oxygen cannot bind to the red blood cells which is usually caused by carbon monoxide poisoning or because there are not enough red blood cells to carry all the oxygen needed, ie severe anemia.

Regardless of the underlying cause, animals with shock typically present with the following common features:

• Weakness/collapse
• Altered mentation (usually dull and poorly responsive)
• Pale/blue or very red gums
• Very fast or very slow heart rate
• Cold extremities
• In septic shock a fever may initially be present but body temperature may be low once shock develops

If you notice any of these changes in your pet you should seek urgent veterinary care. Animals in shock can go downhill very quickly – any delay in treatment can significantly impair the chances of a successful recovery.

It is very important to get your pet to a veterinary practice as quickly as possible if you suspect they are in shock. It is better to make your own way to the practice if you can, rather than getting them to come out to you as they will have all the facilities they need to deal with your pet at the practice. Always ring ahead to make sure there is someone available to see you when you arrive. If there is an obvious source of bleeding, you should apply pressure to the wound using a clean material. If there are any open wounds wrap your pet in a clean towel to prevent any contamination and to minimize heat loss and chilling.

Animals in shock, particularly after trauma, may be in pain or have altered mentation, therefore unpredictable behaviors are not uncommon. Take great care when handling your pet, even if they are usually very trustworthy, to prevent injury to yourself.

When you arrive at the veterinary practice your veterinarian will examine your pet and quickly assess whether your pet is in a stable condition. If they are concerned about your pet’s health they may admit them immediately and start some emergency treatment (such as giving intravenous fluids) before they have time to take a full history from you. Your veterinarian will want to run some blood tests and may need to do some imaging tests (X-rays, ultrasound or CT) to try to establish what the underlying problem is and how severely your pet is affected.

The initial treatments of shock are emergency life-saving measures aiming to restore adequate oxygen delivery to the tissues. Your pet may need emergency treatment with drugs including antibiotics, pain killers and treatments to improve heart function. Intravenous fluids will be given, and your pet may need a supplemental oxygen supply.

Once your pet’s condition is stabilized your veterinarian will need to undertake a series of tests to identify and treat the underlying cause and to deal with any adverse effects of the damaged caused by the shock itself. It is likely that more tests will be needed to monitor response to treatment and to investigate potential causes of the shock. Medical treatment is likely, but many pets will need surgery (particularly if they have suffered a trauma or have a source of infection inside their body). There may be a trade-off between trying to make your pet stronger to withstand an anesthetic and surgery but avoiding too long a delay in surgery because the underlying cause may be making your pet worse. During this period your veterinarian will work closely with you to explain what they are doing and decide on the best time to undertake further procedures.

If treatment is successful and your pet begins to recover there may be a prolonged hospitalization period before your pet will be able to return home.

Shock is a truly life-threatening emergency and you must seek veterinary advice immediately if you are worried about your pet. The earlier treatment is started the better the chances are of your pet recovering.