What is Aortic stenosis?

Aortic stenosis is a dog disease characterized by ventricular outflow tract obstruction on the left side of the heart. Aortic stenosis is a congenital disease and it is especially common in Newfoundland dogs. Aortic stenosis is also fairly common in Boxers, Bulldogs, English Bull Terriers, German Shepherds, German Short-haired pointers, Golden Retrievers, Rottweilers, and Samoyeds. In the United Kingdom, 50% of the reported cases are today found in Boxers.

In dogs with aortic stenosis, the outflow channel located between the aorta (the main artery of the body) and the left ventricle is much narrower than it should be. This narrowing can occur at three different places; at the same level as the aortic valve (so called valvular aortic stenosis), over the aortic valve (supravalvular aortic stenosis), or in the ventricle under the aortic valve (subvalvular aortic stenosis). Subvalvular aortic stenosis is by far the most common form of aortic stenosis in dogs and over 90% of the diagnoses cases are of this type. Supravalvular aortic stenosis is very rare, but can occur in pregnant bitches receiving vitamin D supplementation. 

Symptoms of Aortic stenosis in dogs

A lot of dogs with aortic stenosis will show no symptoms at all and when examined by a vet, the only sign of the problem will be an abnormal heart sound in the form of systolic murmur. In dogs suffering from aortic stenosis, the sound will be louder on the left side of the chest than on the right side; at the level of the heart base.

In dogs that do show symptoms of aortic stenosis, the two most commonly observed symptoms are fainting and exercise intolerance. The dog become weak, lethargic, and may have a poor growth rate. In some dogs, sudden death occurs without any previous warning. Aortic stenosis can be lethal if the cardiac output becomes so impaired that it results in left-sided heat failure. Death from aortic stenosis is however uncommon.

Aortic stenosis prognosis

In order to provide you with a fairly accurate prognosis, the vet will measure the pressure gradient across the stenosis in your dog. This can be done by Doppler or by direct catheterisation. In a dog with a grade 5/6 murmur and a pressure difference of more than 100mm Hg, the prognosis is guarded and the estimated life expectancy is nor more than 3-4 years. A normal life expectancy is likely for dogs with a murmur grade 2/6 and a pressure difference of less than 50mmHg.

Aortic stenosis treatment for dogs

A most dogs, the aortic stenosis is mild enough to require no treatment. If the dog starts to display serious symptoms, the veterinarian can administer medications in order improve the cardiac output while simultaneously controlling any abnormal heart rhythms. Two of the most commonly used treatments are beta blockers (b -blockers) or calcium channel blockers Propranolol is one example of a beta blocker that can be used to treat aortic stenosis in dogs. The normal Propranolol dose is 0.25-0.5mg/kg tid. Procainamide can be administered to dogs suffering from ventricular dysrhythmias.

It is possible to surgically open the stenotic area of the dog’s heart and make it wide.

Cardiovascular and circulatory problems in dogs: (click for more info)
Aortic stenosis in dogs
Congestive heart failure in dogs
Degenerative mitral valve disease in dogs
Dilated cardiomyopathy in dogs
Heart valve dysplasia in dogs
Hemolytic anemia in dogs
Patent ductus arteriosus in dogs
Pericardial effusion in dogs
Pulmonary hypertension in dogs
Pulmonic stenosis in dogs
Thrombocytopenia in dogs
Ventricular septal defect in dogs
Atrial septal defect in dogs
Tetralogy of Fallot in dogs
Von Willebrand disease in dogs