Rausch described respiratory distress as one of the settings where NT-proBNP provides substantial clinical value because these patients can be difficult to evaluate quickly. Though the test result should be combined with history, signalment, physical examination, and additional diagnostics, its high diagnostic accuracy makes NT-proBNP a highly valuable tool in high-stakes emergency scenarios
“This is not going to be the only thing we do. We’re going to do other diagnostics. We’re going to take a good history. We’re going to look at this signalment. But that’s pretty, pretty powerful just for one test,” Rausch noted. “And don’t forget, this is a really difficult setting, right? Cats coming in dyspneic—it’s the worst. Those are fragile patients, they’re hard to do diagnostics on. So, I think this is very useful.”
Predictive value depends on the patient being tested
Rausch explained that the meaning of a test result depends on the likelihood that disease is present in the population being tested
Sensitivity and specificity describe characteristics of a test, but positive predictive value and negative predictive value change based on disease prevalence. A test performed in a population with a higher likelihood of disease is more likely to produce a meaningful positive result
He used systemic hypertension as an example, explaining that a blood pressure reading of 190 mmHg has different implications in a healthy young cat compared with an older cat with chronic kidney disease because the older cat has a higher likelihood of true hypertension
The same principle applies to NT-proBNP
“The chance that a positive assay result is a true positive is directly proportional to the prevalence of disease,” Rausch said
Selecting cats with a higher likelihood of heart disease can improve the positive predictive value of NT-proBNP. Rausch noted that cats with findings such as murmurs, arrhythmias, gallop sounds, or cardiomegaly represent populations in which a positive result is more likely to reflect true disease
In cats with murmurs, NT-proBNP is better at ruling out significant disease than confirming it
In another multicenter study of 146 asymptomatic cats referred to cardiologists because of a heart murmur, arrhythmia, gallop sound, or cardiomegaly, NT-proBNP had a positive predictive value of 62% and a negative predictive value of 94% for identifying moderate to severe cardiomyopathy at a cutoff of 100 pmol/L, Rausch shared during his session.1
Most cats in the study were referred because of a heart murmur, but about 30% were found to have normal hearts
The study excluded cats with conditions that could affect NT-proBNP interpretation, including hypertension, hyperthyroidism, elevated creatinine, and recent fluid administration. Chronic kidney disease can increase NT-proBNP because the peptide is partially cleared through the urine
A positive NT-proBNP result in this higher-risk population indicated a 62% chance of moderate to severe heart disease. A negative result made significant disease unlikely, with approximately a 6% chance that the test missed disease
Rausch emphasized that the test is particularly useful for helping rule out significant disease in cats with concerning findings, rather than confirming disease on its own
Routine screening of low-risk cats can increase false positives
Because predictive values depend on disease prevalence, NT-proBNP becomes less useful when applied broadly to cats unlikely to have heart disease
Rausch cautioned against indiscriminate screening of healthy cats before anesthesia because the lower prevalence of heart disease in that population reduces the positive predictive value and increases false-positive results
“When you look at cats who are just cats in the general population, your positive predictive value is going to fall well below 50%,” he said
A normal NT-proBNP result in a low-risk cat may provide reassurance, but an elevated result may be more difficult to interpret and could lead to additional testing
Interpretation requires clinical context
Rausch discussed how veterinarians can interpret NT-proBNP results while considering the entire patient
Values below 100 are generally considered reassuring, with significant heart disease unlikely. Intermediate values, such as 150 to 250, require interpretation alongside clinical findings and kidney function. Values above 270 are more concerning, particularly when combined with respiratory signs or a heart murmur
However, Rausch noted that more detailed risk estimates for specific NT-proBNP ranges are not yet available
“A 180 can be severe heart disease too, and every once in a while, that 900 can be relatively mild disease or no disease,” he said. “But odds, I’m a lot more worried about the kind of 900.”
Ultimately, Rausch emphasized that NT-proBNP is one component of a broader diagnostic approach. When used in appropriate patients and interpreted alongside clinical findings, the test can help veterinarians identify cats that may need further evaluation while providing reassurance when significant disease is unlikely
- Rausch WP. Uses and Mis-uses of NT-proBNP as a Screening Test for Feline Cardiomyopathies. Presented at: 2026 AVMA Convention; July 10, 2026; Anaheim, CA.
- Fox PR, Oyama MA, Reynolds C, et al. Utility of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) to distinguish between congestive heart failure and non-cardiac causes of acute dyspnea in cats. J Vet Cardiol. 2009;11(suppl 1):S51-S61. doi:10.1016/j.jvc.2008.12.001
