Shock Due to Decrease in Circulation in Dogs

Your dog may go into hypovolemic shock for many reasons, but it is usually caused by a major loss of blood. This can be from an internal injury, external injury, or because of an illness such as a bleeding ulcer or cancer. Hypovolemic shock can affect the respiratory, cardiovascular, renal, and intestinal systems of your dog. When the blood levels are decreased, there are many things going on inside your dog that are life threatening. The blood pressure drops dramatically, causing blood clotting in the capillaries. The lungs and liver start to fail, causing breathing problems and a buildup of toxic substances in the body. The heart will become damaged and kidneys will shut down, causing further toxicity in your dog’s body. Not long after that, the rest of the organs shut down, leading to death.

Shock due to decrease in circulation (hypovolemic shock) is a serious and life-threatening condition that is most often caused by loss of blood due to internal or external bleeding from trauma or illness. Hypovolemic shock can block the oxygen and other essential nutrients from getting to the dog’s tissues because there is not enough blood to fill the vascular system. Without treatment, the affected parts of the body, such as the heart or lungs, can be damaged and can even lead to death.

If the initial injury or illness is not obvious, such as with internal injury and illness, the first signs you may see are:

• Extreme exhaustion
• Severe weakness
• Excessive thirst
• Decreased urination
• Panting
• Pale skin and gums
• Cold ears and extremities
• Cool and clammy skin
• Very weak pulse
• Inactivity and confusion
• Breathing erratically
• Agitation and restlessness
• Vomiting or trying to vomit
• Respiratory failure
• Fainting
• Collapse leading to coma

There are many causes of hypovolemic shock and while some are obvious, such as extreme bleeding, there are many that are not so obvious. Some of the most common causes of hypovolemic shock are:

• Loss of blood
• Excessive vomiting and diarrhea
• Major burns over a large part of your dog’s body
• Ingestion of blood thinning medication (i.e. heparin, warfarin)
• Exposure to extreme cold for a prolonged period
• Bloat (causes a buildup of high pressure in the abdomen)
• Septicemia from internal injury or infection
• Hemorrhage or bleeding ulcer

Before the veterinarian does the examination, it is important to get your dog stabilized by giving IV fluids. Once your dog is safe, tell the veterinarian what led up to the episode and what you think may be causing the hypovolemic shock. The veterinarian also needs your dog’s medical history, which includes any illnesses or injuries recently, vaccination records, if your dog could have been in an accident, and whether your dog has been exposed to other dogs (i.e. dog park, doggie day care) where your dog could have gotten hurt during rough play. A comprehensive physical examination will also be done, including your dog’s weight, body temperature, blood pressure, and heart rate.

The veterinarian will order some tests to determine the exact cause of the hypovolemic shock. If the cause of the shock is vomiting and diarrhea, the veterinarian will first do fungal, viral, and bacterial culture tests to try to find the cause. Further tests will include blood work (i.e. blood count, blood gas, chemistry panel), urinalysis, electrocardiogram (ECG), and radiographs (x-rays). Depending on the results of these tests, the veterinarian may want to do further testing which may include an MRI, CT scan, and ultrasound to try to find the cause of the internal bleeding. If these tests are inconclusive and your dog is still showing signs of shock, the veterinarian may admit your dog to the hospital for continued IV fluids and observation. You may also be referred to a specialist.

The treatment for your dog will depend on the underlying cause of the hypovolemic shock. If the IV fluid therapy needs to continue, your dog will be admitted to the hospital as long as the fluids are necessary to restore your dog’s blood volume and circulation rate. The veterinarian will continue to monitor your dog’s vital signs and possibly administer medications or blood transfusions if needed. Your dog’s urine output will be carefully monitored to be sure his kidneys are working properly. It is best to continue the treatment at the hospital as long as you can for your dog’s best chance of survival and recovery. 

If the veterinarian finds an illness or medical condition that needs to be treated, that will be treated as soon as your dog’s vitals are back to normal because if the underlying problem is not resolved, the hypovolemic shock will return.

With all of the complications that are possible during hypovolemic shock, your dog’s chances of survival are fair to good, depending on the cause of the loss of blood. If the problem is discovered and treated right away (if the reason is treatable), your dog’s chances of recovery are very good. Be sure to keep your dog calm when you bring him home and follow up with your veterinarian as often as directed.