Adjunct ambrisentan therapy had clinical benefits in 5 dogs with sildenafil-refractory pulmonary hypertension

Although sildenafil is used in dogs with severe pulmonary hypertension, they sometimes become resistant and clinical signs deteriorate over time. The objective of this study was to determine the benefits of adjunct ambrisenran therapy in dogs with sildenafil-refracrory pulmonary hyperrension. In 5 dogs with severe pulmonary hypertension with deteriorating clinical signs despite ongoing sildenafil treatment, adding ambrisentan improved appetite, activity, and respiratory functions. Although peak tricuspid valve regurgitation velocity, as measured by Doppler echocardiography, did not necessarily decrease after ambrisentan administration, there was improved partial pressure of arterial oxygen and the alveolar-arrerial oxygen gradient, with no apparent side effects. We concluded that ambrisentan has potential as an adjunct treatment in dogs with pulmonary hyperrension that are refractory to sildenafil therapy.