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by Sandie Snider


Although syncope is not a seizure, it looks so much like a seizure it is worth mentioning on this website.  The term syncope (or fainting) refers to cerebral anemia.  Syncope causes collapse, which may last from seconds to minutes.  Most fainting spells are due to low blood pressure or lack of oxygen delivery to the brain.  Syncope is a symptom not a disease and can be caused by a wide number of disorders.

During a fainting episode of syncope a dog will collapse usually on one side.  The limbs may become stiff or he/she may paddle his/her legs just like with a seizure.  Some things you can look for to determine whether it’s a seizure or syncope are the eyes are not dilated during syncope, heart rate may be normal and temperature is normal unlike with a seizure.  Syncope may also cause the mouth or tongue to turn blue from lack of oxygen.

The cause of syncope may be relatively simple such as moderate to severe anemia, causing inadequate delivery of oxygen to the brain.  Severe respiratory dysfunction or airway obstruction can cause fainting because the blood oxygen level will fall.  There are some problems with the involuntary nervous system that are difficult to diagnose which can lead to fainting.  However, in most cases the cause of syncope is traced to cardiovascular disease (abnormal function of the heart or blood vessels).

A complete medical history should be obtained and your veterinarian should complete a thorough physical examination with an emphasis on stethoscope examination of the heart and lungs.  Some other tests may be necessary such as exercise test.  Pre and post exercise heart rate and rhythm to determine if routine exercise incites an incident or change in heart rate.  Measurement of blood pressure in order to exclude high blood pressure.  An electrocardiogram, chest X-ray, pulse oximetry or test of blood oxygenation, heartworm test.  Blood work including a chemistry panel, CBC, thyroid test and possibly ACTH stimulation to rule out Addison’s disease.  Based on these findings other tests may need to be performed.

This is one of the reasons why it’s so important to have an examination by your vet when your pet first starts having seizures, as it may not be a seizure at all but a problem with your dog’s heart.  The sooner you go to the vet, the better.


Page last update: 09/04/2011

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