Cardiology Resident University of Florida/Small Animal Hospital Gainesville, FL, United States
Background: Cardiogenic pulmonary edema is incompletely explained by increased hydrostatic pressure. Blood-lung barrier dysfunction, as indicated by circulating surfactant, might contribute. Hypothesis:Dogs with acute heart failure (stage C) have higher circulating surfactant protein-B (SP-B) concentrations compared to healthy and stage B2 dogs. Animals:Twenty healthy, 41 stage B2 myxomatous mitral valve disease (MMVD), and 41 acute stage C MMVD dogs.
Methods: Prospective observational study. Serum SP-B was measured using an ELISA kit (LSBio; lower detection 1.56 ng/mL). Lyophilized canine lung was a positive control with Western blot verification. Dogs were fasted for serum collection. Samples from C dogs were collected within 12 hours of admission. Results are expressed as median (range). SP-B was compared between groups (Kruskal-Wallis test). Relationships between SP-B and clinical variables were explored with Spearman’s correlation coefficients (rs). Proportion of dogs with detectable SP-B having daily cough and < 1-month survival was tested with Fisher’s exact test.
Results: Circulating SP-B was detected in 9/102 dogs (9%) with no group differences (healthy: 0 (0-36.8 ng/mL), B2: 0 (0-32.5 ng/mL), C: 0 (0-161.9 ng/mL; P=0.93). The proportion of dogs with detectable SP-B was not different between coughing and non-coughing dogs (P=0.68) or < 1-month survival (P=0.12). SP-B was weakly correlated with total furosemide administered (P=0.04, rs=0.3173). Conclusions and clinical importance:Circulating SP-B was detected in a small number of dogs but not more so in acute C dogs. If total furosemide dose relates to disease severity, its weak relationship to SP-B might indicate barrier disruption in some dogs.
