Ventricular tachycardia is an arrhythmia that is caused by abnormal electrical impulses that are generated somewhere within the ventricles of the heart.  These rapid, repetitive extrasystoles or contractions can be intermittent or continuous in nature, and may be caused by cardiac disease, abnormal serum levels of calcium or potassium, as well as splenic or gastrointestinal diseases. 

Ventricular tachycardia can be life-threatening, and while some dogs be asymptomatic, this arrhythmia can lead to hypotension, destruction of cardiac muscle tissue, collape, and even sudden death.  Treatment of this arrhythmia should be initiated if the pet's heart rate is greater than 200 beats/minute, and the arrhythmia has been diagnosed by an electrocardiograph. 

Treatment is also necessary if the pet is showing any clinical signs, such as weakness, syncope (collapse), seizures, or shock.   Anti-arrhythmic drugs such as lidocaine, procainamide, and sotalol may need to be used initally to convert the arrhythmia in an acute episode, and may need to be continued indefinately.  If the arrhythmia is well controlled, treatment may be slowly decreased after a period of 2 to 3 weeks.