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THE
1998 ABC HEALTH SEMINAR
Dr. Theresa
Garton,
Health Committee Reporter
(Published on the Boxerunderground website http://www.boxerunderground.com)
The 1998 ABC Health Seminar
was a fact filled program. Dr. Neil Harpster started off the seminar with
data from his screening clinic last year [1997]. He is a very kind man with
impeccable credentials. His talk was interesting, but perhaps not really
geared toward the lay audience. Things to take away from his part are that
last year, he found a murmur in one puppy (eight months or younger), and
five murmurs in adult dogs. This is a total of six murmurs in 121 boxers. I
think that statistic is quite a relief, especially compared with some of the
data from England, but is still obviously a concern.
Dr. Harpster found no EKG
abnormalities in the eight months and younger group, but did find three in
the eight months to 12 months group. These three adolescents represented
16.7% of the adolescent group. The adult group included 15 with EKG
abnormalities, or 15% of the total.
This EKG data is particularly
concerning when you remember that EKG's only pick up a VERY small proportion
of abnormalities. Of the abnormalities noted, 12 had arrhythmias, five had
axis deviation (3 L and 2 R), and one had first degree A-V block. This again
from a total of 121 boxers.
Remember that the EKG only
runs for 6 minutes. The arrhythmia has to be VERY significant to display
itself consistently on an EKG. IF the arrhythmia occurs regularly (those
with Boxer Cardiomyopathy do NOT), then a single arrhythmia every six
minutes would correspond with 10/hour, or 240 per 24 hours. This is more
than twice the number of PVC's many investigators feel definitely mark the
presence of BCM, or if you believe some of Dr. Meurs’ data, could be almost
FIVE times the number she considers significant. We have no idea what
percent of boxers affected with BCM this EKG data "caught," but I don't
think it takes much imagination to see how serious our problem could be if
the 15-16% "caught" at ABC really do have BCM, and if this, as I believe,
only represents a small portion of those actually affected.
This year (1998), many
abnormalities were again noted, including one dog that Dr Harpster arranged
emergency treatment for, as he was afraid its arrhythmia (repeated runs of
ventricular fibrillation) would kill the boxer before it got home. The
owners were NOT aware there was a problem with the dog, as it had had NO
symptoms. Some may find it interesting that great efforts were made this
year to make the testing more private and confidential.
Now for the points I took
home from Dr. Meurs’ talk: Dr. Meurs is a vivacious and warm speaker, and
gets to the "meat" of the matter quickly. She started with a description of
the study, and thanked all who contributed. She expressed being overwhelmed
with the support she had received from ABC members. Dr. Meurs then reviewed
her data, and attempted to anticipate questions and address them. Here is a
review of some of the topics she discussed.
MODE OF INHERITANCE OF BCM
Many of us have suspected
that BCM is passed on by an autosomal recessive mode of inheritance, because
to outward appearances, it seems to skip generations. However, Dr. Meurs
calls it "the silent killer," because without Holter monitor data, we really
have no idea how many asymptomatic dogs actually have BCM, but just never
have any symptoms. She discussed in her talk a family of five dogs, both
parents and three puppies from one litter. All dogs were over five years
old. Both parents were affected (the data that follows is from foggy memory,
not notes, so please be kind <G>). One had 240 PVC's, the other, 2400. Of
the puppies, one had 500, another "some" (30-60, I believe), and one had
ZERO. If BCM were autosomal recessive, two affected individuals could ONLY
produce 100% affected offspring, so Dr. Meurs thinks that BCM is AUTOSOMAL
DOMINANT. "Autosomal" means that it is not sex linked - that the incidence
is the same in males and females.
HOW MANY ABNORMAL BEATS
ARE SIGNIFICANT?
Dr. Meurs later described the
basis for the numbers used to differentiate "affected" from "not affected."
She reviewed for us approximately three studies of Holter data in various
breeds of dogs. I know one of the studies was a very large one, of beagles.
This study determined that a normal number of PVC's/24 hours for dogs was
nine (yes, one digit) or less. One of the other studies was a multiple breed
study. This study found most dogs had (I think I am remembering this
correctly) 10-20 or LESS. One of the dogs tested as "normal" had 54 PVC’s;
significantly, it was a BOXER. Dr. Meurs used the data derived from these
studies to justify her opinion that - even giving boxers the "benefit of the
doubt" - your boxer should certainly have 50 or fewer PVC's per 24 hours.
RULING OUT OTHER CAUSES OF
HEART PROBLEMS
Dr. Meurs also discussed
parvovirus, having anticipated questions about whether BCM could be the
result of either environmental parvo infection, or some iatrogenic problem
resulting from vaccination programs. She spent some time discussing this in
detail. What I took away from this part of her talk was that they ARE able
to isolate parvovirus in cases of heart failure proven to be secondary to
parvo; but have NEVER, NEVER, EVER isolated parvovirus from dogs that had
been determined to have BCM.
In a subsequent one-on-one
conversation, Dr Meurs also discussed attempts to investigate a possible
role of thyroid hormone, or derangements thereof, in the cause of BCM. She
said researchers had found no correlation between thyroid values and BCM.
HOW DO WE SCREEN FOR BCM?
Dr. Meurs stressed that echos,
of any description, color doppler or not, are a very poor screen for BCM, as
90% (YES, NINETY) of those dogs with full-blown BCM have NORMAL echoes. She
discussed the problem many of us have in getting local cardiologists to do
anything but echoes. Dr. Meurs again mentioned that BCM is unfortunately
misnamed, in that it is NOT generally a disease of the heart muscle (though
it is in some cases), but in the great majority of cases, is a disease of
the electrical conduction system of the heart that initiates and regulates
the heart beat. She did discuss the few cases of heart muscle failure in
boxers, and stated that these VERY FEW dogs may actually have another
disease, and are more likely to respond to L-carnitine therapy.
Dr. Meurs said that ideally,
all boxers would have a thorough exam, echo, and Holter, but that if money
were an issue, a cardiac auscultation (examination with a stethoscope) by a
cardiologist, and a Holter were a pretty good screening program. In another
private conversation, a breeder approached her while I was speaking to her,
saying she had been informed that she had "wasted" her money on color
dopplers. Dr. Meurs and her associate, Dr. Spier, said that the money was
not wasted, as it was an excellent screen for aortic stenosis and other
valve problems, but that it just was not a screen for BCM.
HOW WIDESPREAD IS BCM?
Dr. Meurs gave some
statistics regarding Holter monitor findings in her study at the meeting,
but in a private phone call graciously gave me some updated statistics she
had prepared for cardiology meeting after her return from ABC: 17% of those
boxers studied (over 100 now) had zero PVC's. 50% of those studied had 0-100
PVC's per 24 hours, 25 % had 100-1000, and 25% had OVER 1000. So, 50% were
in the category most investigators believe represent affected dogs.
Dr. Meurs did not have a
breakdown of the 50% that had 100 or fewer PVC’s, though most investigators
believe dogs with 50-100 PVC's/24 hours are "suspicious," if not affected.
The dogs with fewer than 100 PVC's tended to be younger dogs (two-five
years) and very old dogs. We have no data yet to tell us whether the two
year old with 50 PVC's will later become the eight year old with 1000. Dr.
Meurs said the mid-range of PVC's (100-1000) tended to be in dogs four-six
years old, and that the dogs with more than 1000 PVC's tended to be older
dogs (I am assuming she meant older than six).
Here is the really scary
part: Dr. Meurs says that even one PVC puts your dog at some risk of sudden
death. Obviously, those with 100 PVC's are believed to have the disorder,
and are thus at great risk of collapsing spells and sudden death. However,
as she said in her talk, there really is no data that proves dogs more
severely affected (ie, 1000 PVC's) are at any more risk of sudden death than
those less severely affected ("only"100). Both groups are at equal risk,
according to the data we have today. |
