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by Katherine Nevius, Minstrel Boxers

Over the past few months, slowly but surely I’ve been subjecting my current crew to the rigors of heart testing recommended by the American Boxer Club. Two have been holtered thus far, and all three echoed. This has been accomplished under the auspices of Dr. Luis Braz-Ruivo at his clinic, Beltway Veterinary Cardiology, near Annapolis, Maryland. Dr. Braz-Ruivo (who, I’m certain, would be delighted to have us learn how to spell and pronounce his name <G>) is the cardiologist who provides echocardiogramscreening at our National Specialty. During the hours I’ve spent in his company, I’ve learned a great deal that’s of crucial interest to me and, I’m sure, to others who breed and show boxers. I’ve also heard a lot that’s simply entertaining -- like the fact that, when colorflow Doppler imaging begins, the unique swishing heartsound causes all boxers (and he means ALL of them) to stop panting, prick up their ears and listen attentively.

Furthermore, NO other breed of dog behaves this way. :-) That information, of course, is of no practical use, but I trust that what follows will be.

Those who’ve read my posts on the Showboxer List have heard me claim that auscultation (listening with a stethoscope) – even by a board certified cardiologist – is an insufficient diagnostic tool in ferreting out potential valve disease in the boxer. I have mentioned that, in my first litter, a bitch cleared by Dr. Harpster at ABC at the age of twelve months, on echo a year later proved to have a flow rate (the speed/force at which blood moves through the valve) of 2.6, and a clearly audible murmur. Even I could make it out, so distinct was its odd sound. Thus, I’ve exhorted folks not to be sanguine when they’re told – especially by a general practitioner – that their boxer is free of murmur. For one thing, the doctor may be missing something. For another, things change.

Even more interesting to me, though, is the flip side of that event. Not every veterinarian is capable of drawing accurate conclusions based upon what he does hear.

Many of us have experienced the spinal chill that comes with being told that our dog has a murmur. (Will it be of the benign puppy variety and abate on its own? Will it develop into something worse, possibly lethal? Does it, in fact, sound worse than it really is? Those are typical thoughts that course through the minds of breeders everywhere, whether they test or not.)

A couple of years ago, that information alone would have been sickening; after all, we’re aware that, in the United Kingdom, for example, subaortic stenosis is routinely diagnosed ringside via auscultation. The presence of a Grade 2 murmur can spell the end of a boxer’s breeding future.

However, there’s good news for those of us on this side of the pond. Dr. Braz-Ruivo’s experience suggests that that particular valve disease is more prevalent in the U.K and, furthermore, that not all murmurs are created equal. In American boxers, they do not necessarily indicate evidence of ANY problem – even those that, upon auscultation, may be categorized as Grade 2.

In fact, he leaves the impression that most boxers have murmurs to some degree or another, and that many of them are only of the flow variety. Here’s the crucial point. Whereas a strict constructionist cardiologist, without extensive experience in the boxer breed, may label a flow rate on Doppler in the high 1’s (or, in some cases, even the low 2’s) as valve disease and disqualify it from breeding, Dr. Braz-Ruivo’s view is that it’s often not evidence of disease at all. For disease to be present, along with the flow rate there are additional criteria to be met. They are as follows:

1. Laminar vs. turbulent flow: Is there evidence of obstruction that causes the blood flow through the valve to be turbulent rather than smooth?

2. Aortic insufficiency: Is a leaky valve present? This may be seen clearly via the Doppler image.

3. Sudden change in flow rate: Is there rapid change in upward velocity -- for example, a sudden move from 2.0 to 3.0?

If the aortic flow rate is in the high 2’s, the flow is turbulent, a leak is evident and flow velocities change quickly, then the diagnosis is clear. The boxer has heart valve disease and must not be bred. But the salient point here is that the simple presence of a murmur – even above a Grade 1 and present on Doppler -- is insufficient evidence to signal disease. There are cardiologists in this country, and I have personal experience with one, who would not recognize the distinction and may well assign an inappropriate diagnosis. That, of course, can be detrimental to a breeding program.

This sort of difference of opinion is, to say the least, sobering. Are there breeders out there spaying and neutering beautiful animals who are, in fact, normal for the breed? Dr. Braz-Ruivo would suggest that yes, that’s likely. Normal FOR THE BREED. Not ideal, but standard and eminently acceptable.

Of course, it’s not only the aorta that’s of interest in our breed. Among other items, Dr.Braz-Ruivo checks pulmonic flow, inflow of the mitral valve, and atrial and ventricular size and function. To me, an interesting tidbit emerged from his having Dopplered 52 boxers at ABC this year. Fifty-two of fifty-two had tricuspid valve leaks. That would tend to suggest that they're the norm, wouldn't it? My foundation bitch has a slight one, although it's never been audible. It, too, was discovered on Doppler. Had I listened to my original cardiologist, who adopts a zero tolerance posture when it comes to breeding animals, Ch. Scarborough Take It To The Limit, dam of this year’s Best of Winners at ABC, with zero VPC's on her first Holter and a single VPC on her second at four years of age, would never have been bred. That would have been a sizable error on my part. Fortunately for me, I contacted two boxer cardiologists and was told that slight tricuspid valve regurgitation is a dime a dozen in the breed, and not a thing about which to be concerned. In fact, Dr. Braz-Ruivo says that 70% of ALL canines present some degree of tricuspid valve regurgitation.

Nevertheless, the fact of those 52 boxers who share my bitch’s idiomatic state of the heart tends to supply further evidence that boxer hearts are NOT state of the art. What we need to learn is what to accept and what to dispose of. That’s not an easy task, as Dr. Kate Meurs (the cardiologist who leads the ABC funded study of boxer cardiomyopathy) has discovered of late. It appears that the evidence she’s gleaned in her few years’ study of our dogs presents her with quandaries of interpretation. She’s not ready to offer hard and fast rules. That leaves us wondering if, indeed, there are many.

My main concern is that, currently, there's no standard evaluation available for us -- that every cardiologist will do his own thing, according to the sort of training he's received or the nature of the clientele at whatever facility trained him, and we'll have acceptable dogs being cast aside for no reason.

A friend who’s a breeder judge coined a term for our original vet – the one with the slash and burn mentality: She calls her the Nazi cardiologist. <G> This vet seeks physical perfection. And sadly, after nearly a hundred years of linebreeding (in effect, selecting for unsavory traits right along with the good ones), perfection is unattainable in purebred dogs of any breed. Unfortunately, I'm certain that there are more of that kind of doctor than there are of the Braz-Ruivo sort. All we can hope is that researchers get their findings published, and with some haste, because things are pretty murky out here in boxer breeder land.

These facts, though, should never be used to condone a refusal to look at one’s breeding stock. Your vet hasn’t heard what he considers a meaningful murmur and you’re sanguine about breeding the bitch? Don’t be. Give her six months and she may present unequivocal symptoms of disease. Your stud dog’s never had an episode of syncope and is a sensational athlete? So what? Holter him and see if he may not be throwing thousands of VPC’s each day, with multiple runs. Know what’s what, or you perpetuate KNOWINGLY what breeders in the past have unknowingly wrought: Boxer hearts that simply aren’t right, and will continue to worsen without the help of us all.

There are so many things that people keep to themselves, or about which they obfuscate, out of fear, that there may be plenty of relatively benign experiences that terrify breeders -- things that we all need to know, as Dr. Braz-Ruivo does, that might make us feel less alone and far less afraid that, in some way, we've failed.

If you can afford to show a dog, you can afford to test it. Ethically, you cannot afford not to.

Dr. Braz-Ruivo points to local Golden Retriever clubs to which you may not be admitted as a member if you refuse to test. That’s a group of people with a realistic, hopeful attitude – one that results in a realistic, hopeful goal. They make no excuses, and they do the right thing because it absolutely has to be done. We need to be realistic, too. As he told me, "I’d be happy to minimize these defects. Anyone who thinks we’re going to solve the problem in five years has unrealistic expectations. But I think it will come over time."

Part of the reason that may happen is due to this man’s efforts. I’m happy (and, of course, he’s not <G>) to report that Dr. Braz-Ruivo spends most of his weekends reading Holter results. At the time of this writing, he has 35 to review. That’s evidence that many of us have come around to understanding the imperative nature of heart testing. Although cardiomyopathy tends to present us with a bleak picture in terms of diagnostic elusiveness, that needn’t be so with valve disease. If your vet hears a murmur, don’t panic. But don’t avert your eyes, either. Seek out board certified cardiologists with experience who understand what the true litmus test ought to be.

Don’t throw the baby out with the bath water. But, for heaven’s sake, don’t fail to give it the bath!

Katherine Nevius
Minstrel Boxers
BoxerKate@earthlink.net
http://www.minstrelboxers.com 

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