Biomarkers for differentiation of causes of respiratory distress in dogs and cats: Part 1--Cardiac diseases and pulmonary hypertension.

Objective: To review the current veterinary and relevant human literature regarding biomarkers of cardiac disease leading to respiratory compromise.

Data Sources: Veterinary and human medical literature: original research articles, scientific reviews, consensus statements, and recent textbooks.

Human Data Synthesis: Cardiac troponins (cTn) and natriuretic peptides are routinely used in human medicine.

Veterinary Data Synthesis: Although biomarkers should not be accepted in lieu of gold standard diagnostics, they may be useful in directing care in the stabilization process. Biomarkers of congestive heart failure (CHF) include natriuretic peptides, cTn, and endothelin. cTnI is useful in differentiating causes of pericardial effusion, but is unlikely to be useful in differentiating CHF from other causes of respiratory distress. The most extensively studied and promising cardiac biomarker is amino-terminal probrain natriuretic peptide, although a bedside test is not currently available. Other natriuretic peptides have also proven useful, but have lower availability. Endothelin is unlikely to be clinically useful. Although critically evaluated for their use in cardiac diseases, many of the biomarkers are affected by more than one type of respiratory or systemic disease. Several cardiac biomarkers are increased in cases of pulmonary hypertension (PH), but discerning CHF alone from PH or a combination of heart disease and PH is challenging when evaluating biomarkers alone.

Conclusion: At this time, there are no point-of-care tests for biomarkers that can reliably differentiate among causes of dyspnea of cardiac origin in dogs and cats, although there are reference laboratory tests that show promise and future development of point-of-care tests that may be useful in certain situations.