Hezzell MJ, Rush JE, et al. Differentiation of cardiac from non-cardiac pleural effusions in cats using second-generation quantitative and point-of-care NT-proBNP measurements. J Vet Intern Med. 2016 Jan 27.
There you are, the veterinarian, on a busy Friday afternoon at the clinic. The schedule is packed, and then Mrs. Smith frantically walks in with her beloved 4 year old neutered Persian cat, Mr. Muffins. Mr. Muffins started open-mouth breathing at home about 30 minutes ago. He’s stressed out from the car ride to the clinic and now has dilated pupils, open-mouth breathing, purplish tongue, and a pronounced abdominal breathing effort upon expiration. You give him some butorphanol to relax him and put him in an oxygen cage. What’s up? Is it cardiac failure with underlying cardiac disease, feline infectious peritonitis, chylothorax, pyothorax, asthma attack, neoplasia, electrical shock, etc.. More simply put – Is it cardiac disease, or non-cardiac disease, that is the question.
Regardless whether this is cardiac disease or not, this is a very fragile cat. Let’s say we determine this cat has pleural effusion (i.e. fluid around the lungs), drain most of pleural effusion from his chest and stabilize him, for now. You probably have ruled out pyothorax, but many other pleural effusions (i.e., transudates, modified transudate, chylothorax, etc.) could still be secondary to cardiac or non-cardiac diseases and you need to get closer to the underlying diagnosis in order to treat appropriately.
Researchers at the University of Pennsylvania and collaborators evaluated a new quick in-hospital test (IHT)a and a second generation quantitative ELISA testb that measure N-terminal pro-B-type natriuretic peptide (NT-proBNP) in plasma or pleural effusion. proBNP and NT-proBNP are secreted into the blood predominantly from the heart in response to excessive stretching of heart muscle cells secondary to cardiac disease. NT-proBNP turns out to be a useful marker in humans and cats for diagnosing cardiac disease.
In this prospective cohort study, 21 and 17 cats in a US cohort, and 22 and 18 cats in the UK cohort were classified as having cardiac or non-cardiac pleural effusion, respectively. NT-proBNP tests were performed for each cat. Results demonstrated that measurement of NT-proBNP in plasma samples using either an in-hospital test or a quantitative ELISA test can differentiate cardiac from non-cardiac disease with good diagnostic accuracy.
Back to Mrs. Smith and Mr. Muffins. An in-hospital NT-proBNP test would be quite useful to help determine if his symptoms were most likely due to cardiac or non-cardiac disease, and thus help direct additional diagnostic tests and/or therapy. In the past, NT-proBNP testing usually required sending a blood sample out to an outside laboratory and results took at least 24 h to report. [GO]
a SNAP® Feline proBNP, IDEXX Laboratories Inc., Westbrook, ME
b Cardiopet® Feline proBNP, IDEXX Laboratories Inc., Westbrook, ME
Humm K, Hezzell M, et al. Differentiating between feline pleural effusions of cardiac and non-cardiac origin using pleural fluid NT-proBNP concentrations. J Small Anim Pract. 2013 Dec;54(12):656-61.