Prognosis

1. Mild VSD – presents no morbidity.
2. Severe VSD – if pulmonary hypertension develops:
   • response to therapy and prognosis are unknown, but likely very poor
   • if heart failure develops, the animal will likely succumb within 6 months.

Comments:

• chronic excessive fluid flow through the pulmonary circulation may result in pulmonary hypertension and right to left shunt flow.
• this is likely a rare occurrence.
• if it does occur, polycythemia (increase in RBC mass of the blood) may develop and can be treated with hydroxyurea, which suppresses bone marrow production of RBCs.