Vasovagal Syncope in Dogs

Syncope in a dog can resemble an epileptic seizure.
Thinkstock/Stockbyte/Getty Images

Watching your dog lose consciousness is a scary experience, even if he comes to right away. Fainting -- formally known as syncope -- in dogs occurs from various causes. If your dog appears to faint, you should get the pet to the veterinarian as soon as possible. If the fainting relates to your dog's cardiac health, it's known as vasovagal syncope.

Vasovagal Syncope

Your dog probably didn't just collapse out of the blue. If he's suffering from vasovagal syncope, there was likely an episode that triggered excitement in your dog, causing his heart rate to drop and subsequent fainting. The fainting episodes generally don't last long -- perhaps 20 seconds or so -- but they can seem an eternity while you wait for your dog to recover. Your dog might also urinate, defecate or emit odd noises during the fainting episode.

Breed Predisposition

Although any dog can develop vasovagal syncope, it's more prevalent in certain breeds. These include German shepherds, dachshunds, pugs, miniature schnauzers, boxers and cocker spaniels. Because heart disease occurs more frequently in older canines, vasovagal syncope is more likely to affect aging dogs.

Diagnosing Vasovagal Syncope

To determine why your dog faints, your veterinarian will put him through a battery of tests, including chest X-rays, cardiac ultrasound and an electrocardiogram, and will conduct blood tests and a urinalysis. It's likely your dog will wear a Holter monitor for 24 to 48 hours. This device, worn like a dog coat, continuously monitors your pet's heart rate via a portable monitor. While your dog wears the Holter monitor, you must record the time and duration of regular canine activities, such as walks, sleeping and eating.

Heart Failure Treatment

Your vet can prescribe various medications to ease symptoms of congestive heart failure in your dog. These include diuretics for reducing fluid accumulation around the heart and lungs, angiotensin-converting enzyme inhibitors, or ACE inhibitors, for blood vessel dilation, and drugs to strengthen the cardiac muscle. While the long-term prognosis for dogs with heart failure isn't promising, medication can give your dog a good quality of life for his remaining time.

Episode Prevention

While you can't fully prevent fainting episodes once your dog is diagnosed and treated, you can take precautions. Avoid placing your dog in situations in which he's likely to become excited. Such excitement could affect his heart rate, causing fainting. That might mean leaving him home rather than taking him to certain events, warning your kids not to engage in strenuous play with the dog, or it might mean the end of romping in the dog park.