Causes of Fainting and Dizziness in Dogs

Can dogs faint?

Fainting, also known as syncope, is a serious clinical sign that needs to be addressed and treated immediately and accordingly. Diagnosis of the underlying condition is important in the treatment and prevention of future fainting episodes in dogs. If left untreated or undiagnosed, fainting and dizziness in dogs can result in various health complications and progress to severe diseases that can be fatal to canine patients.

If your dog has had fainting episodes, you must visit your vet immediately for a consultation. Early diagnosis of the cause of fainting in dogs is key to successful treatment and prevention.

Fainting vs. Seizures in Dogs

Syncope is the medical term used for fainting. This is characterized by the sudden loss of consciousness, often due to the lack of oxygenation in the brain. Most dogs that have syncope will lose consciousness for a short period and recover instantly, often without showing any disorientation after.

Most dog owners confuse syncope with seizures because of the similarities in how both issues manifest. It’s important to note that syncope and seizures are different clinical signs with different causes. Unlike syncope, which happens spontaneously followed by a quick recovery, seizures go through 3 different phases and recovery is much slower, with apparent disorientation after the episode.

Being able to differentiate between the two will help you and your vet diagnose your dog properly to come up with appropriate treatment. Chances are, your dog will have already recovered from the episode by the time you get to your vet, and a detailed description of how the episode happened will help your vet arrive at a proper diagnosis.

Common Causes of Fainting and Dizziness in Dogs

As mentioned above, most fainting or syncope incidents in dogs are due to the lack of oxygen going to the animal’s brain. This is often a result of reduced blood flow to the brain due to compromised heart function. Cardiovascular diseases account for around ⅓ of syncope cases in dogs.

Several heart problems can result in reduced brain blood supply and eventual syncope. Abnormal heart rates such as arrhythmias (inconsistent heart rate) or ventricular tachycardia (elevated heart rate) can compromise the circulation of blood to the brain and cause fainting. Conditions that affect the conduction of electrical impulses in the heart such as AV (atrioventricular) blocks can also cause syncope in dogs.

Fainting can also be a symptom of neurological diseases. Changes in the activities and the transmission of nerve impulses in the brain can cause loss of consciousness and syncope in canine patients. The presence of brain tumors has also been reported to cause syncope in dogs.

Nutrition can also cause fainting in dogs. Deficiency in nutrients such as glucose, or imbalance in certain electrolytes like sodium and calcium in the blood can be a predisposing factor for fainting in dogs.

The use of certain drugs like diuretics can increase the rate of elimination of nutrients and electrolytes and can lead to fainting spells. Excessive use of vasodilators can decrease peripheral blood pressure and reduce the blood supply to the brain leading to fainting.

How can my vet tell if my dog fainted?

Syncope in itself is not a medical condition but rather a symptom of a more serious underlying cause. Diagnosis of the underlying health problem causing the fainting episodes is important to be able to come up with an appropriate and proper treatment.

A detailed description of the episode is important in arriving at a diagnosis for syncope. When you bring your fainting dog to the vet, he or she will ask you a series of questions regarding the fainting, when it happened, what the circumstances are during the episode, were there any possible triggers, and any pertinent medical history that can help pinpoint the cause of syncope.

A complete and detailed history will be useful in helping your vet arrive at a definitive diagnosis. A thorough physical exam is also essential in narrowing down the probable causes of fainting. Your vet will run comprehensive blood work to look for infection, electrolyte imbalance, and to rule out some of the other common causes of fainting.

Diagnostic imaging such as radiographs, ultrasound, and echocardiogram may be needed to assess heart function since cardiovascular disease remains to be the most common cause of fainting in canine patients. An ECG (electrocardiogram) can also help identify the specific heart problem that may be causing the syncope.

What is the treatment for fainting in dogs?

Treatment for syncope ultimately depends on the underlying condition. A proper diagnosis is needed to determine the appropriate treatment and prevent further fainting episodes in the affected dog.

Heart conditions can be treated with inotropic drugs and diuretics to regulate blood pressure and improve the perfusion of internal organs, most especially the brain. As mentioned, most syncope cases happen due to a lack of blood circulation and oxygenation in the brain. Medications like Pimobendan and Furosemide help control arterial blood pressure and improve circulation of the blood, ensuring proper blood and oxygen supply to the brain and the blood vessels associated with it.

Electrolyte and nutrient deficiencies can easily be managed with proper nutrition and, in some cases, nutrient supplementation. Care must be taken when starting your dog on electrolyte supplements as excessive levels can also result in health problems such as seizures and tremors.

Depending on the extent, organ involvement, and location, tumors causing syncope in dogs can be removed surgically or treated via chemotherapy. A biopsy is usually needed before deciding on surgery, as there are certain locations where a tumor might prove to be very tricky to surgically remove.

Read more:

Dilated Cardiomyopathy in Dogs

Vestibular Disease in Dogs

How can I tell if my dog is blind?

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