A loud right-apical systolic murmur is associated with the diagnosis of secondary pulmonary arterial hypertension: Retrospective analysis of data from 201 consecutive client-owned dogs (2006-2007)

Canine pulmonary arterial hypertension (PAH) remains under-recognized and under-treated despite being prevalent. This retrospective study investigated whether selected historical and physical examination findings were associated with the diagnosis of canine PAH, defined as tricuspid regurgitation (TR) with a confirmed systolic pressure gradient ⩾35 mmHg. Two hundred and one client-owned dogs (PAH group, n = 96; control group, n = 105) were studied. Dogs in the control group had TR with a confirmed systolic gradient <35 mmHg. All dogs underwent a complete physical examination and a complete echocardiographic assessment.A loud systolic right-apical murmur (RAM) was significantly associated with TR ⩾ 35 mmHg. The proportion of dogs with PAH significantly increased as the RAM grade increased, with odds ratios of 4.4-37.6 for Grades 3/6-5/6 (P = 0.004 to <0.001), respectively. A stronger right-than-left apical-murmur had a positive predictive value (PPV) of 83% and was 96% specific for TR ⩾ 35 mmHg, and when combined with syncope, it had a PPV of 92% and was 92% specific. A Grade ⩾4/6 RAM had a PPV of 85% and was 93% specific. Syncope with a Grade ⩾4/6 RAM had a PPV of 94% and was 92% specific. Ascites combined with a Grade ⩾4 or ⩾5/6 RAM had a PPV of 100% and was 100% specific for TR ⩾ 35 mmHg. For each of these three murmur categories (Grades ⩾4/6, ⩾5/6, and a louder-right-than-left murmur), when detected with no concurrent ascites or syncope, the positive likelihood ratio varied from 4.6 to 6.4. A loud systolic RAM in dogs with degenerative valve disease is highly suggestive of concurrent PAH.