Pro-BNP heart test (information by JP Yousha)
Several people have asked me lately about pro-BNP testing (brand name CardioPET), mostly saying they have been told this can be used as a "baseline" for heart disease in a potentially at-risk dog, and some being told they can screen for heart disease in their breeding stock using this test. Neither is true. And, except for very specific situations (which I outline below), this test really has little value for this breed at this time. So your money could be better spent. This is not my opinion, this is the information I have received in consultation with board-certified cardiologist (both clinical and research DVMs).
ProBNP is a non-specific blood test for non-specific heart disease.
It measures certain compounds found in the blood when the heart is undergoing stress. It can only diagnosis congestive heart failure (advanced heart disease), which is essentially where every compromised heart (for whatever reason) ends up. It cannot clear a dog for diseases like DCM and SAS, and, in fact, a dog could have had several echocardiograms where heart disease was amply evident, while still getting "clear" results on a BNP. It cannot tell you or your veterinarian what KIND of heart disease your dog has either. So either way, a follow-up is going to be necessary if you get a positive BNP. And a negative BNP cannot be interpreted as the dog having a healthy heart.
ProBNP was created as an inexpensive alternative to the more specific diagnostic tests for heart disease, especially those that require a referral to a specialist (like the echocardiogram). It's essentially a test developed to help your average practicing vet with the pet clientelle unwilling, unable or unconvinced about doing more viable diagnostics where heart disease is suspected. It's a fairly new tool, so quite naturally a lot of veterinarians are eager to try it out, see how useful it might be for their own individual practice. And it certainly has its uses, but they are very limited with talking about Danes.
ProBNP is normally used when a dog (or cat) has clinical signs of what could be heart disease, and the client (for whatever reason) isn't able or isn't willing to get more definitive heart testing done. Idexx created this "CardioPet" (what ProBNP is & it is used in both cats & dogs) to catch overt (clinically significant) heart disease earlier on in theory, so as to be able to manage the disease more effectively. But it's real use currently is to see how effective therapy IS once instituted. IOW where you have a Dane already diagnosed with a specific heart condition, then proBNP may certainly be used to gauge how effective that treatment is--at this it's proven very useful I am told.
But otherwise its current use is very limited.
For example, diagnostically its usefulness is VERY limited, and it has very little relevance for a dog (especially Dane) breed, as it cannot define what KIND of heart disease the dog has (it could be heartworm disease or DCM and the test results would be the same--hegative in the early stages and positive when the dog has end-stage heart disease). And it cannot diagnose even generalized heart disease until the disease is actually fairly advanced. SO for a breeder, once once you get a positive CardioPet result, you are going to have to go do the tests (like an echo) actually recommended to diagnose specific heart disease. And a negative proBNP has no real meaning at all beyond being able to say the dog doesn't have advanced heart disease--he could have undiagnosed heart disease still.
And because proBNP cannot predict disease--it can only record what is already a situation where the pet is in congestive heart failure (which is the end stage of most all heart disease)--it would make more sense for most of us in Danes to get routine exams (to ideally include echos) done by a cardiologist. Less than that is going to miss a lot frankly, and miss our most significant forms of heart disease in the most treatable stages. (Again an echo done on a dog BEFORE they have signs of heart disease--when they would still test negative on this CardioPET--is the best time to start treating. Nevermind this gives the breeder more time to intervene in the potential spread of something like DCM in their bloodline.)
So also as a SCREENING test it's value is VERY limited: it could be used as a screening test under certain circumstances where more reliable & definitive testing isn't an option (or in other breeds than ours potentially, as well as in cats). But those circumstances are critically limited for us, since any positive result would mean more specific testing was in order, and a negative result would not alone rule out any sort of heart disease.
Since this blood test has no specificity, and has no predictive value, it just doesn't have a wide applicability, especially in a breed like ours. If dealing with a high risk individual/family, there might be some relevance to using CardioPET in between more specific screenings, as more than annual exams by a cardiologist might prove impossible (for various reasons, including prohibitive cost). Certainly if treating a dog already diagnosed with heart disease, the CardioPET blood test can monitor how effective the treatment is (as it records the stress level the heart is under, so hopefully you'd get a negative result with your heart dog, meaning his treatment was effective).
If in a remote area, it might make sense to combine this test with telephonic ECGs (CDs of an ultrasound?) sent off to a specialist (both for diagnostic and possibly screening applications), as an attempt to gain more data than just an auscultation done by an average practitioner. If on a budget, it might be added in to a plan to space out echocardiograms. But the catch there is that it could then give the breeder or owner a false sense of security, because the proBPN test only records end-stage heart disease, where the heart is already compromised, and in doing so, it cannot tell you what sort of disease caused the heart failure. So with Great Danes it would simply be better to budet for better (more effective) testing 99% of the time, as the take-home message is, by the time the proBNP can register a Dane's heart disease, the dog is already experiencing congestive heart failure.
Hope that's helpful. jp
Best regards, JP Yousha
Chairman, Health and Research Committee
Great Dane Club of America