RESEARCH COMMUNICATIONS OF THE 28th ECVIM-CA CONGRESS

Degenerative mitral valve disease (DMVD) is the most common acquired heart disease in small‐breed dogs, resulting in poor apposition of the mitral valve (MV) leaflets during systole. This leads to MV regurgitation, which is clinically detected as a left apical systolic heart murmur, the intensity of which is classically classified according to a 6‐grade scheme. Past studies have shown that an increase in heart murmur intensity over time is associated with worsening of DMVD lesions, with thrilling murmurs (TM, i.e., of grade V/VI and VI/VI) associated with more severe disease. The objectives of this retrospective study were to characterize the epidemiological, clinical, and echocardiographic features of dogs with TM related to DMVD, and to identify parameters associated with survival. The case records of small‐breed dogs (under 15 kg) diagnosed with TM related to DMVD were reviewed. The study population consisted of 374 dogs (median age at detection of TM=10.7 years [IQR=8.6‐12.5], male‐to‐female ratio=1.8). The most represented breeds were Cavalier King Charles Spaniel, Yorkshire Terrier, Poodle and Chihuahua. Thirty‐six dogs had a concurrent hemodynamically compromised systemic or cardiac disease and were therefore excluded from the subsequent analysis. According to the ACVIM classification, 24%(82/338) were in stage B2, 61% (207/338) in stage C and 7% (22/338) in stage D. Chordae tendineae rupture was identified in 75% (254/338) of the included dogs, severe pulmonary hypertension (systolic pulmonary arterial pressure >75 mmHg) in 27% (90/337), and tachyarrhythmias in 46% (157/338). Regurgitation fraction (RF), assessed using the PISA method, was >30% for all dogs (median value=70%[IQR=59‐76]), which is consistent with moderate to severe MV regurgitation.