While many cardiologists medically manage AS with beta blockers, there is no known successful surgical intervention. Researchers
continue to attempt to find a correction for AS.
Valvular dysplasia affecting the mitral or tricuspid valves are also seen in both dogs and cats, though not commonly. Labrador
Retrievers, in particular, are prone to tricuspid valve dysplasia (TVD), and Bull Terriers are prone to mitral valve dysplasia
(MVD). Dysplasia refers to an abnormality in the formation of the valve, which results in regurgitation or stenosis. The consequence
of valve dysplasia is generally congestive heart failure.
On physical examination, the most common finding is a systolic murmur. However, tricuspid valve dysplasia may not cause any
murmur at all, which makes screening breeding dogs for TVD especially difficult. Medical treatment is necessary once CHF has
developed, and though attempted, surgical correction of MVD or TVD is not typically successful.
Ventricular septal defects affect both dogs and cats. The septum fails to form correctly, which results in a communication
between right and left ventricles. Because of the difference in pressure between the ventricles, blood passes from the left
into the right.
On physical exam, small defects cause loud murmurs on the right side of the chest, often with a palpable thrill. Smaller defects
actually have softer murmurs because the difference in pressure is lower. Large defects may even cause equilibration of pressures
between each side of the heart, leading to cyanosis due to deoxygenated blood from the right side of the heart entering systemic
circulation. Therefore, smaller defects causing loud murmurs have the best prognosis. Large hemodynamic defects cause left
heart volume overload and congestive heart failure. Treating the CHF as a result of the VSD is generally the only therapy
available. The location of a VSD may allow it to be corrected via a catheter procedure, but these types of VSDs are extremely
Atrial septal defects are relatively uncommon in dogs and cats, but these defects have been found in certain families of dogs,
especially Standard Poodles. ASDs result from a failure of the atrial septum to form properly. There is a variety of different
defects that arise from the abnormal formation of the septum. The most common physical exam finding is a soft basilar murmur
that is generally from relative pulmonic stenosis due to a large volume of blood passing through the RVOT. As with VSDs, the
right morphology and location of ASD may allow for correction, but this is rare. Typically, no treatment is necessary. ASDs
are often a sequela of TVD or PS due to right sided volume or pressure overload.
There are a large variety of other more rare defects, which may occur alone or in combination with other congenital anomalies.
Tetralogy of Fallot, for instance, is a four part defect with a large over-riding aorta, VSD, right ventricular hypertrophy,
and PS. Other congenital defects include endocardial cushion defects, transposition of the great vessels of the heart, and
cor triatriatum dexter or sinister.