“Seizure or syncope (fainting) take your dog to the vet to be safe.  If you can get a video of the episode this is helpful to help distinguish between the two” says Dr. Kelly Churchill.

What is fainting, and what are the reasons a dog might faint?

Fainting, or syncope, is the sudden loss of consciousness or a sudden and marked weakness. It may be associated with numerous medical conditions and can be caused by anything from low blood sugar and neurological diseases to severe heart disease.

Neurologic problems may include:

• Seizures
• Abnormal brain activity

Cardiac problems may include:

• Abnormal heart rhythms (such as sick sinus syndrome)
• A-V block
• Ventricular tachycardia
• Ventricular fibrillation

Collapsing is not fainting

Fainting in dogs needs to be differentiated from the more common problem of collapsing. With collapse, loss of consciousness typically doesn’t occur—in other words, your dog or cat may be weak and unable to get up, but he’s still conscious. There are numerous causes for collapse including:

• Dehydration
• Shock or severe hypotension (e.g., low blood pressure)
• Internal bleeding or severe anemia
• Heat stroke
• Neurologic problems (e.g., seizures)
• Neuromuscular problems (e.g., botulism, tick paralysis, etc.)
• Musculoskeletal problems (e.g., Lyme disease, joint problems, etc.)
• Cardiac problems (e.g., arrhythmias, etc.)
• Endocrine problems (e.g., low blood sugar)
• Poisonings (e.g., xylitol, etc.)
• Pregnancy

Thankfully, some causes of fainting can be treated, but often require more advanced therapy. For example, if an abnormally low heart rate (e.g., sick sinus syndrome, A-V block) is detected, sometimes a permanent pacemaker needs to be placed into the heart to help stimulate it. With severe neurologic signs, anti-seizure medications may also be necessary—depending on what the preliminary tests indicate.

What should I do if I think my dog might be having an episode?

What to Do

• Immediately position the pet with the head down and the hind quarters elevated. This will improve brain blood flow.
• Cover the pet with a blanket to preserve body heat.
• If the pet vomits, make sure he or she does not inhale any of the vomitus into his lungs by keeping the head down.
• Try to videotape the episode quickly. Often times, your veterinarian or veterinary specialist (e.g., neurologist, cardiologist) can determine the cause by physical appearance.
• Seek immediate veterinary attention.

What NOT to Do

• Do not administer anything by mouth. It can be aspirated into the lungs and cause serious problems.
• Do not slap the pet or douse him with cold water trying to shock him into consciousness.
• Do not fail to seek veterinary attention just because the animal recovered quickly and seems fine now. Several of the conditions that cause fainting or dizziness are extremely serious and require diagnostic tests in order to determine the cause and prevent future episodes.

What happens after I take my dog to the vet?

Once you get to your veterinarian or emergency veterinarian, the doctor will need to check the heart rate on an electrocardiogram (ECG) right away to look for the presence of abnormal arrhythmias, and perform blood work to make sure that there are no metabolic causes (e.g., liver, kidney, etc.) or blood sugar problems causing the episode.

If neurologic problems are detected, further evaluation by a neurologist is warranted. Unique tests such as an electroencephalogram (EEG) may need to be done to monitor the brain for any unusual seizure activity. Alternatively, an MRI or spinal tap may also be necessary. If cardiac abnormalities are detected, a referral to a cardiologist for an ultrasound of the heart (e.g., echocardiogram), x-rays of the heart, and a Holter monitor (to monitor the heart rhythm) may be necessary.