Cardiac Arrest in Dogs - Symptoms, Causes, Diagnosis

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sad dog sick dog
Sad Dog Sick Dog

What happens if cardiac arrest occurs in your dog? It’s frightening to think about your dog’s heart suddenly stopping. Although the likelihood of this happening to your dog is relatively low, it’s a good idea to understand cardiac arrest in dogs. Learn what to do if your dog experiences cardiac arrest.

What Is Cardiac Arrest in Dogs?

Dogs do not experience heart attacks in the same way that humans do. However, they can experience heart failure that ultimately stops the heart.

Cardiac arrest (or cardiopulmonary arrest) occurs when the circulatory and respiratory systems cease to function. Simply put, it means that the heart has stopped functioning. A working heart muscle pumps oxygenated blood throughout the body. When the heart stops pumping blood, the body cannot function. Cardiac arrest is a cause of death.

When a dog experiences cardiac arrest, the process is rapid. The dog will collapse, lose consciousness, and stop breathing (not necessarily in that order). All other bodily functions will rapidly begin to shut down. Unless the dog can be resuscitated within minutes, death will occur. Generally speaking, a dog cannot survive if the brain and other organs are deprived of oxygen for more than about four to six minutes.

adult tricolor rough collie closeup photography
adult tricolor rough collie closeup photography

Sadly, the chance of successful cardiopulmonary resuscitation after cardiac arrest is low. Even if the dog can be resuscitated, continued survival is statistically unlikely. However, the chances of survival often depend on the actual cause of cardiac arrest.

Causes of Cardiac Arrest in Dogs

Many different conditions can lead to cardiac arrest in dogs. Some are medical emergencies that require immediate veterinary attention. Others are chronic diseases or even dormant conditions. The outcome depends on the severity of the damage to the heart and other organs as well as the advancement of the disease process itself.

  • Trauma. This is a common cause of cardiac arrest. Excessive blood loss or injuries to the body can directly impact the heart’s ability to function. Some injuries affect a dog’s ability to breathe properly. Without adequate oxygen supply to the brain, the rest of the body cannot get the signals they need to function. Lack of oxygen can also cause direct injury to the heart muscle. Head trauma can cause damage to the brain that results in cardiac arrest. Dogs suffering cardiac arrest due to trauma may or may not respond to CPR. Some dogs may recover from some types of trauma.
  • Heart disease. This can lead to heart failure, ultimately causing cardiac arrest. Some forms of heart disease can lie dormant until sudden cardiac arrest occurs. In most cases, dogs develop heart disease that gradually worsens until they eventually suffer cardiac arrest. Heart disease may be congenital (present at birth) or acquired (develops over time). There are many different types of heart disease seen in dogs. Senior dogs may develop heart disease. Certain dog breeds are especially prone to various forms of heart disease. Fortunately, many types of heart disease can be managed medically, extending survival times and improving the quality of life in the meantime.
  • Toxin Exposure. This can adversely affect many bodily functions and lead to cardiac arrest. Poisonous substances may include plants, foods, chemicals, and more. Symptoms depend on the type of toxin and how much was absorbed into the body.
  • Heartworm disease. This will eventually cause cardiac arrest if left untreated. When too many adult heartworms invade the dog’s heart, the organ can no longer properly function and stops. Also, even as little as one worm can cause death by breaking off and traveling to the lungs. This is known as a verminous embolism. The damage to the lungs can be severe and result in not enough oxygen getting to the heart, leading to cardiac arrest.
  • Anesthetic Complications. Although uncommon, this can lead to cardiac arrest. Fortunately, most veterinary hospitals use monitoring equipment that will signal problems before the heart stops. The veterinary team will take the necessary actions in an attempt to reverse the process and wake up the dog. Though many dogs will survive anesthetic complications, some cannot be revived.
  • Electrocution. This can cause the heart to stop suddenly. This is why it's important to keep electrical cords tucked away so dogs cannot chew on them. Chewing electrical cords is common in puppies.

Some other diseases and disorders can lead to cardiac arrest. Any health problem that cannot be cured or treated can have enough impact on the organs and other bodily functions that lead to the heart ultimately stopping.

short-coated brown dog opening mouth
short-coated brown dog opening mouth

What to Do If Your Dog Goes Into Cardiac Arrest

It will be very obvious if your dog experiences cardiac arrest. Your dog will lose consciousness and stop breathing. The gums may appear bluish or very pale. The pupils may be dilated. If anything like this happens to your dog, it's important to begin first-aid steps as soon as possible.

If your dog is unconscious and not responding to attempts to rouse him, check for signs of breathing. Try to hear the heartbeat by placing your ear against the left side of the chest just behind the elbow. You may also be able to feel the heart in this location in some dogs. You can also try to feel a pulse by putting two fingers on the inside of a back leg (in the middle of the inner thigh near the belly). If you cannot detect a heartbeat or pulse, the dog's heart has likely stopped, although, finding a heartbeat or pulse can be difficult in overweight dogs.

Although CPR is best performed by trained professionals, there is no time to waste. If your dog is not breathing and has no heartbeat, you cannot cause more harm by attempting CPR. You will need to breathe into your dog's mouth in between chest compressions. It's a good idea to learn how to properly resuscitate your dog before a situation like this occurs. You may even wish to take a pet first-aid class.

If your dog's heart begins to beat again and he can breathe, the danger is not over. There is an underlying reason for the cardiac arrest, so your dog's heart could stop beating again at any moment.

white and tan dog
white and tan dog
long-coated brown dog on gray surface
long-coated brown dog on gray surface
close-up photography of copper and white Siberian husky
close-up photography of copper and white Siberian husky

It is important to get to a veterinarian as soon as possible while keeping yourself safe. Be sure you know where the closest open veterinary office is at all times. Familiarize yourself with the veterinary emergency clinics in your area in case something happens after hours.

Remember, if you think your dog is in cardiac arrest, do not delay. The faster you act, the better your dog's chance of survival. Unfortunately, not all dogs can be saved, no matter how skilled the medical team is.