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Causes of Fainting in Dogs

Has your dog ever fainted? It can be a terrifying experience to witness your furry friend suddenly collapse and lose consciousness. But what causes dogs to faint? Understanding the underlying causes can help you identify potential health issues and seek appropriate treatment.

While fainting in dogs is relatively rare, it can be a sign of an underlying medical condition.

From heart problems to neurological disorders, there are several factors that can contribute to fainting episodes in dogs.

By exploring these causes, you can better understand how to keep your dog healthy and prevent future episodes.

Causes of Fainting in Dogs

In this article, we will delve into the various causes of fainting in dogs, ranging from cardiovascular issues to heatstroke, and offer insights into how to recognize the signs and seek proper veterinary care.

By being aware of these potential causes, you can ensure the well-being of your beloved pet and take the necessary steps to keep them safe and healthy.

Symptoms Pre-ceding the Fainting Episode

Dogs may develop a series of symptoms before they actually ”blackout”.

The symptoms generally consist of the following:

  • Weakness
  • Glassy Eyes
  • Vocalization
  • Rigid Legs
  • Lack of Bladder and/or Bowel Control

Causes of Fainting in Dogs

Causes of Fainting Episodes in Dogs

Low Blood Sugar

Low blood sugar, better known medically as hypoglycemia, takes place often in toy-breed dogs.

These furbabies are prone to hypoglycemia and for this reason, the condition is often known as ‘toy breed hypoglycemia’.

Carrying some Karo Syrup or some honey may be helpful to prevent the dog from collapsing.

Warning symptoms suggesting a hypoglycemic attack are shaking, drowsiness, incoordination, slow heartbeat, cold temperature, and loss of consciousness.

Cardiovascular Problems

A troubled heart may be unable to deliver sufficient oxygen-rich blood to the brain ad therefore, it can cause episodes of collapse in dogs.

Heart problems that can cause fainting spells may include cardiomyopathy, arrhythmias, heartworm disease, and congestive heart failure.

Neurologic Disorders

Possible underlying medical conditions such as epilepsy and other neurologic disorders can be the reason for a loss of consciousness in dogs.

A seizure-like episode, or syncope, is often characterized by muscle twitching and disorientation which can lead to a faint.

In some cases, a dog may appear to faint from fear or excitement, but this is not truly fainting.


Low red blood count causes anemia and in severe anemia, the dog may be unable to receive sufficient oxygen-rich blood to the brain.


The mechanism remains the same: the dog may suffer a severe coughing spell or asthma attack to the extent of not being able to receive sufficient oxygen.

Heat Stroke

On hot days, dogs can suffer severe heat stroke which can lead to fainting.

If the dog is exposed to high temperatures for a prolonged period of time or engages in strenuous activity without proper ventilation, their body temperature will rise and they will be unable to receive sufficient oxygen.

Symptoms include panting, heavy salivation, rapid breathing, lethargy, and collapse.


Ingestion of certain toxins can cause fainting in dogs.

For instance, chocolate and raisins are known to induce low blood sugar levels that result in fainting.

If you suspect your dog has ingested any toxic substances, it’s important to seek immediate veterinary care.

Collar pressure

Some dogs may faint after too much pressure is placed on the dog’s neck by the collar.

This syndrome is known as hypersensitive carotid sinus syndrome.

In Conclusion

While fainting may be a scary episode most dogs recover just fine in a few seconds. However, dogs fainting and exhibiting trouble breathing along with pale or bluish gums need immediate emergency treatment.

The underlying cause of repeated fainting episodes needs to be addressed. It is especially important because it is often attributed to important functions related to cardiovascular or pulmonary function.

It is also important to be aware of the various causes of fainting in dogs to ensure their well-being.

Whether it’s a heart condition, low blood sugar, or simply overheating, being proactive in identifying and addressing these issues can save your furry friend’s life.

So, keep a close eye on your dog’s health, seek veterinary advice when needed, and provide them with a safe and comfortable environment.

Remember, a little knowledge and care can go a long way in keeping your four-legged companion happy and healthy!

Robert B.

Wednesday 16th of September 2020

Good information

Debbie P

Wednesday 24th of June 2020

I had no idea. Thanks for the great article.

Cheryl Markle Bomar

Saturday 15th of February 2020

Thanks for the info!!

LeAnn Harbert

Saturday 15th of February 2020

This is great information to have. I hope I never experience this with any of my dogs.

Antoinette M

Friday 14th of February 2020

Very interesting. I didn't know about fainting spells in dogs.

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