Differentiating between congestive heart failure and respiratory disease as a potential cause of the respiratory signs may prove challenging for clinicians. In these cases, plasma N-terminal fragment of BNP (NT-proBNP) may give the clinician a first hint about the reason for the respiratory signs.
NT-proBNP is a molecule formed after cleavage of brain natriuretic peptide (BNP), a peptide stored in cardiomyocytes. As heart disease progresses, the chambers become more stretched. BNP is released in greater quantities, therefore levels of NT-proBNP increase.
However, increased NT-proBNP values may be observed in other conditions.
- Renal disease may increase the NT-proBNP levels above the reference interval, following decreased renal clearing.
- Systemic and pulmonary hypertension and drugs (e.g. diuretics) that alter the volume status of the patient.
- Certain infectious diseases (e.g. babesiosis in dogs causing infectious myocarditis).
Furthermore, levels may vary across dog breeds. Labrador Retriever and Terra Nova have the highest NT-proBNP concentration medians, which can be 3 times as high as those observed for Dachshunds. It has also been reported that Greyhounds have higher NT-proBNP serum levels than other breeds. Yet, further studies are necessary to establish specific reference values for each breed.
Conversely, very low values are suggestive of inappropriate sampling or sample degradation and a repeat sample should be submitted in those cases. Furthermore, NT-pro-BNP levels may decrease with cardiac medications.
Although particularly helpful in diagnosing cardiac disease in dogs, NT-proBNP should be used concomitantly with other diagnostic methods such as echocardiography, radiography, electrocardiography, medical record, and evaluation of clinical signs.
NOTE NT-proBNP is quite unstable and time, as well as temperature, has an impact on the result. Here, at Battlab, we ask our vets to spin the EDTA tube immediately after venipuncture, to transfer the plasma in a plain tube and to freeze it. The sample should arrive to us frozen, in a freezer pack. For more information, do not hesitate to contact us.
