Sick Sinus Syndrome (SSS) in Dogs

Sick Sinus Syndrome (SSS) is a condition where the sinus node (normal pacemaker of the heart) is diseased and not responding normally to the body’s needs.  

This disease is often a result of fibrosis/scarring of the sinus node or surrounding tissue, which prevents the signals from forming or being conducted.  

Affected patients can range in severity from mild (no clinical signs) to severe (collapse, lethargy, weakness – especially with excitement).  Often, the sinus node stops suddenly and a long pause occurs, followed by a ventricular escape beat.  

This condition carries the risk of sudden death.  

Medications may be attempted to increase the sinus rate; however, these are often ineffective or only effective in the short-term.  A permanent pacemaker is usually required to ensure the heart rate does not drop below the minimum programmed rate.