What dogs get this disease? This congenital disorder is most often identified in brachyocephalic (e.g. bulldogs, Boston terriers), terriers (Jack Russel terriers), Samoyeds, and Labrador retrievers. Other breeds can also be affected such as boxers and Newfoundlands.
CAUSE: Pulmonic stenosis is a congenital heart defect of the semilunar valve that is between the right ventricle and the pulmonary artery (great vessel that takes blood to the lungs). The leaflets of this valve are thickened and/or partially fused together. Sometimes the supporting structure known as the annulus is also narrow. Dogs that have this congenital defect have a wide range of stenosis to include very mild to severe obstruction to blood flow from the heart to the lungs. This defect may be associated with other congenital defects too (e.g. ventricular septal defect, overriding aorta, subaortic stenosis). Because this disease is associated with certain breeds it is likely that it is at least in part due to a mutation in as yet unidentified gene.
CLINICAL SIGNS: Many dogs have no clinical signs. Dogs with mild disease never develop any problems and may live a normal lifespan. However, dogs with advanced disease may have exercise intolerance, collapsing, arrhythmias, or heart failure.
DIAGNOSIS: Virtually all dogs with clinically important pulmonic stenosis will have a cardiac murmur heard when the chest is listened to with a stethoscope. This is auscultation of the chest. Often, but not always, how loud the murmur is in this particular disease correlates with severity. An important example of the exception to this general statement is with tetralogy of Fallot where several congenital defects are present together with pulmonic stenosis.
TREATMENT: Balloon valvuloplasty is the treatment used for valvular pulmonic stenosis. Not every dog with this defect can be helped by this procedure. Some dogs have dramatic improvement while others have adequate results. Echocardiographic examination can give indicators of dogs that are most likely to be helped. This treatment involves the passage under general anesthesia of special catheters which when an attached balloon is inflated, tears the restricted valve leaflets. Measurements of the pressure gradient before and after treatment give information as to the success of the treatment. This treatment involves specialized training of the veterinary cardiologists and the use of expensive specifically ordered catheters for each patient. Our service has published several manuscripts concerning the treatment of pulmonic stenosis. Some dogs may be treated with beta-adrenergic blockers (e.g. atenolol) either with or without the balloon valvuloplasty.
PROGNOSIS: The prognosis depends on the severity of the disease and the response to treatment.
How should an affected dog be monitored? The frequency and intensity of the monitoring depends on each patient, the severity of the disease, the response to treatment, and the status of other body systems. Usually after the balloon valvuloplasty a dog is examined 3 months later and then yearly.