Background and Aim: Pulmonary hypertension (PH) is a common complication of degenerative mitral valve disease (DMVD). Sildenafil, a phosphodiesterase-5 inhibitor, has effects in reducing pulmonary arterial pressure by selectively dilating pulmonary vessels. The study aimed to evaluate the effects of sildenafil in combination with conventional therapy in dogs with PH caused by DMVD.

Materials and Methods: Fourteen dogs diagnosed with PH secondary to DMVD Stage C on conventional therapy were randomly assigned to placebo (n=7) and sildenafil (n=7) groups. On day 0, the recruited dogs underwent physical examinations, clinical score assessments, electrocardiography, systolic blood pressure measurements, blood collection, thoracic radiography, and echocardiography for baseline. The dogs then received a combination of conventional therapy with sildenafil or placebo every 8 h for 1 week. On day 7, all dogs underwent the baseline evaluations again.

Results: The sildenafil group experienced a significant decrease in estimated systolic pulmonary artery pressure (sPAP) (p=0.043) from day 0 to day 7. Moreover, the total clinical scores were decreased in dogs treated with sildenafil relative to those who received the placebo (p=0.007); however, the lung scores were not different between before and after treatment with sildenafil.

Conclusion: Sildenafil had a synergistic effect with conventional therapy in reducing the estimated sPAP and clinical scores in dogs with PH secondary to DMVD.

Keywords: degenerative mitral valve disease, dogs, pulmonary hypertension, sildenafil.