Table 2 Dogs classified by the RPAD Index and according to the presence/absence of symptoms and by parasite burden. Data are shown as number of dogs (n). Animals were considered having mild pulmonary hypertension (30–55 mm Hg) with a RPAD Index between 28% and 35%, moderate pulmonary hypertension (56–79 mm Hg) with a RPAD Index between 23% and 27% and severe pulmonary hypertension (> 79 mm Hg) with a RPAD Index ≤ 22%. When the RPAD Index was ≥36% the dog was considered normotensive

From: Evaluation of pulmonary hypertension and clinical status in dogs with heartworm by Right Pulmonary Artery Distensibility Index and other echocardiographic parameters