Pulmonic stenosis is the second most common congenital heart defect in dogs. This diagram shows three different types of pulmonic stenosis. There is a valvular type with commisural fusion, an immediately sub-valvular fibrous type, and infundibular type in which there is severe primary right ventricular hypertrophy (RVH). The first two types have secondary RVH.

ps1-n	psa1a-n Valvular pulmonic stenosis, highlighted in yellow, due to failure of valves to separate into leaflets (cusps).
ps1b-n Subvalvular pulmonic stenosis, highlighted in yellow.	ps1c-n Infundibular pulmonic stenosis, highlighted in yellow, showing muscular separation of the right ventricle into two chambers (above and below the stenosis).