Q + A session on Cardio
Lori Siemens, DVM - Board Certified Cardiologist
A brief introduction of myself
1992 - DVM at UC Davis 1993 - Completed a small animal internship at Michigan State University 1995 - Completed a cardiology residency at UC Davis 1996 - Became board-certified in veterinary cardiology, Currently in private practice as a veterinary cardiologist in Sacramento.
I have lost two Dobes to cardio.both came up with different signs. One at 9 years, I
found him on the floor with blood coming out of his mouth. I rushed him to emergency
and kept him going for 4 months.the other lost weight, although he didn't seem
to lack interest in food, but he did lack energy, when he was taken to the Vet she said he
had a faint heart murmur.there had been no other sign that night he started the
coughing and he was sent to the Bridge the next morning.he had advanced cardio. My questions:
Is there any way of being able to tell conclusively that a dog has Cardio.are there
signs, loss of weight, lack of energy. something that would encourage us to take our
dogs to the Vet. Can the Vets tell with a ge neral test, or do they have to do x-rays.
Your sad stories are examples as to why Doberman dilated Cardiomyopathy (DCM)
is such a devastating disease. One of its hallmarks is that it usually has a long (2-3 year)
occult phase during which the dog sho ws absolutely no symptoms. Oftentimes the first
indication that they have the disease is when they go into congestive heart failure or die
suddenly from an arrhythmia. Owners often blame themselves that they should have
noticed something earlier. They shouldn't because it is simply impossible to know from
their outward appearance and activity level that the disease is brewing. Just having a vet
listen to the heart or take chest X-rays still will not pick up most cases of occult DCM.
An irregular heart beat is one of the earliest indicators that DCM is present. If frequent,
the vet may hear it with a stethoscope or see it on an ECG strip. If infrequent, it would
take a 24 hr ECG (Holter monitor) to detect it. Statistics show that 30% of Dobies in the
occult phase of DCM die suddenly from their irregular heart beats (arrhythmias.)
If caught in the early stages, can medication keep cardio in remission or will it
automatically progress, regardless of medication and diet.
Most of the time the disease progresses no matter what supplements or medications
are given, even if caught in the early stages. One study did show that less than 5 % of the
time, there was a bit of improvement or regression of the disease when the dog was given
a nutritional supplement called L-carnitine. The dose for an adult Dobie is 2 grams
every 8 hours. If an arrhythmia is found, antiarrhythmic medications can be tried in an
attempt to stave off sudden death. It's not always effective though.
What is your opinion about the relationship of DCM to a low protein diet and possible
taurine deficiency due to that diet?
Most Dobies with DCM do not have a taurine deficiency, although a serum or plasma
taurine level is certainly worth doing and most veterinary diagnostic labs have this test
available. A few dogs have been shown to have carnitine deficiencies. As far as I know,
there is only one lab in the country that runs this test. It's almost easier to just supplement
with carnitine and see if there is a positive response. I have not heard of DCM being due
to a low protein diet, although it is important in any dog to make sure it is getting
What echo criteria is are you using for the diagnosis of occult DCM?
There are published echo measurements that are used by cardiologists to make a
diagnosis of occult DCM. The problem is that each author has their own opinion as to
where the cut-off is between a normal dog and an abnormal dog. It can be very hard to
differentiate between a dog who is normal with borderline low measurements and a dog
who has mild occult DCM whose measurements are almost normal. It gets easier as the
disease progresses of course. If you want one study's cut-off (Sandra Minors and
Michael O'Grady in a paper published in 1998), they used a left ventricular internal
dimension in diastole of greater than or equal to 46mm or a fractional shortening of less
than or equal to 16%. All of these dogs were asymptomatic for the disease. I try to look
at the whole picture and use several other measurements, such as the E-point septal
separation, to form an opinion. The presence of ventricular arrhythmias would also
make a dog more likely to have occult disease, even if the echo measurements were not
within the occult DCM ranges. If the dog is a "gray zoner" then a recheck echo in 6
months is recommended to see if the measurements have changed.
What therapy is recommending for occult DCM and you have any data with respect
of slowing of progression to frank DCM with her chosen therapy?
There is nothing that has been proven to consistently stop or slow the progression of
early DCM. I'll use antiarrhythmic drugs if ventricular arrhythmias are present and start
digoxin when the heart muscle becomes significantly weak. ACE inhibitors are used for
significant heart chamber dilation. Heart healthy supplements such as taurine, L-
Carnitine, coenzyme Q10, and omega fatty acids are also recommended in the early
stages, but there is no proof that they do a lot of good except in the rare truly deficient
If the incidence of occult DCM is as high as some centers have reported. Do you have
any thought of prophylactic strategies for ALL Dobermans?
The best way to screen for early DCM is with a 24 hour Holter monitor once a year
combined with a yearly echocardiogram. This is HIGHLY encouraged for active
breeders and may also be recommended for pets. However, since we don't have a
treatment that stops the disease from progressing, early detection in a pet may not help
his overall survival, but certainly would prepare the owner for what lies ahead instead of
being surprised. Efforts must be made to eliminate any breeders with DCM as this is the
key to truly try to decrease the incidence of the disease.
I have heard of some people that have had cardio diagnosed in their dog, others dogs
just drop dead while playing etc.what are the signs that we should be paying attention
to, if any?
No early symptoms are generally seen at home during the occult phase.
Can the Holter monitor truly catch the early warning signs of cardio?
Yes. Ventricular arrhythmias are considered the earliest evidence that DCM is
present. Greater than 50 abnormal beats in a 24 hour period would be highly suspicious
of emerging DCM.
Does health and exercise play a role in helping to decrease the odds of cardio (similar
to heart attack) or are the genetics predetermined and eventually the heart will go
Unfortunately no. A supreme athlete will develop the disease just as easily as a couch
potato if he is genetically predisposed.
I have a 9 1/2 year old Dobe who is experiencing erratic heartbeats (discovered during
routine exam). His heart has been checked by a cardiologist and I have been told that his
heart function is good (and lungs clear), but that the erratic beats are very evident on his
EKG and even through the stethoscope. The only medication he is receiving is
Atenolol. I am told I will come home one day and likely find him dead. Is there
anything at all that can be done to control this arrhythmia, and if he tries to die on me,
should I attempt to revive him?
Beta blockers, such as atenolol, are the only class of drugs that in human studies were
shown to decrease the incidence of sudden death from ventricular arrhythmias (which is
most likely what your dog's erratic heart beat is due to.) So I think it is a good choice for
your dog. However, dogs still die while taking any antiarrhythmic medication if their
heart disease becomes bad enough. Omega 3 fatty acids (such as found in fish oil) were
shown to have some protection for sudden death as well. If you see him collapse
suddenly, try to determine if he is breathing or if his heart is still beating. Occasionally
people mistake a fainting episode for a heart attack--if he faints, he will revive himself
without assistance. If there is no heart beat or breathing, you could try mouth-to-nose
resuscitation and chest compressions, but without a cardiac defibrillator, your chances of
reviving him are slim.
What's known about the inheritance pattern (if any) of cardio?
As far as I know, the mode of inheritance has not been established. However, I have e-
mailed one of the experts on the subject (Dr. Calvert at UGA) to see if he is aware of any
research that has not been published yet.
Can a dog who suffers sudden death syndrome be resuscitated (spelling??) and has
there been any cases where it was documented that the dog lived (and how long)
I've seen several Dobies with severe DCM have cardiac arrest at clinics I have worked
at. Just one was able to be resuscitated and lived an unknown time afterwards. There is
more of a chance of the dog surviving for at least some period of time if it happens in a
vet clinic with access to a cardiac defibrillator. If it happens at home, the chances are
much less likely that he will survive.
Do the dogs who drop dead suddenly do so from ventricular tachycardia, and if so,
would it not be advisable to place implantable cardioverter-defibrillators (ICDs) in these
dogs as soon as they start to show abnormal changes in EKGs.
Sudden death is usually caused by a sustained bout of ventricular tachycardia which
then degenerates into ventricular fibrillation. It would be wonderful if we were able to
implant cardiac defibrillators and there has been some discussion about trying to do so.
However, I believe the cost of the ICDs is the major limiting factor unless, like with
pacemakers, you have a human hospital that would donate used ICDs or those that have
exceeded their shelf- life. Another problem, especially with Dobie DCM, is that if the
arrhythmias don't end their lives, their heart disease will progress, usually shortly
thereafter, to the congestive heart failure stages which will.
In a recent discussion with a long time breeder - she says "older" Dobes (8+years)
with congestive heart failure do NOT have the type of Cardiomyopathy that is hereditary
and that CHF is a "normal" part of aging. Please you explain the difference between
sudden death Cardiomyopathy and congestive heart failure.
Congestive heart failure is not a normal part of aging. I have echoed many ancient
dogs (even a few Dobes!) with beautiful hearts. CHF, be it in geriatric people or dogs,
is always due to true pathology (disease) of the heart.
Dilated Cardiomyopathy causing sudden death is the same disease as DCM causing
congestive heart failure. They are just 2 different outcomes. With sudden death, the
associated arrhythmias are the more lethal part of the disease, and cause the dog to drop
over dead suddenly. 25-30% of Dobies with DCM die in this manner. The other 75%
may also have ventricular arrhythmias but they are less aggressive and don't cause death.
Instead, these dogs die eventually from congestive heart failure (fluid accumulation in
the lungs and/or in the abdomen) or from side-effects of the medications being used to
treat the CHF.
What is her best guess at when DNA testing for cardio is likely to be available?
I am not involved directly in any research in this area and nothing, as far as I know,
has been published regarding a DNA test. I am trying to contact the veterinarian who has
published the most papers on Doberman DCM to see if he has any additional
information. It would be great news if someone was getting close to developing this test.
If one is to claim a dog is "Cardio Clear," must they do both & must it be done every
It really depends on how strict the breeder wants to be---there are no set rules. In
general, we recommend a 24 hour Holter monitor and echocardiogram at least once a
year for active breeders.
If the SF in an echo is 30+ and a Holter shows 100 PVC's/hour, should this dog be on
meds for acute sudden death?
Yes. Even though this dog's echo shows that it has normal heart function, the large
number of premature ventricular contractions puts him at risk for sudden death.
If an echo was all that was done, would you say this dog is Cardio clear?
No. Some dogs with normal echoes ha ve significant ventricular arrhythmias on the
Holter which is an indicator of occult DCM.
Is a 5-10 minute EKG a false sense of security if it shows just a few PVC's?
Actually, quite the contrary. Even 1 PVC on a 10 minute EKG is abnormal.
Is a 24 hour Holter the best indicator for an acute sudden death episode?
We think so, but there are certainly some dogs with lots of PVCs that don't die
suddenly from them. We can't seem to correlate the number of PVCs with the chance
for sudden death either, since one dog with 600 PVCs/24 hrs may experience sudden
death while another with 2,000/24 hrs won't. There are other features on the Holter that
we look for to try to predict a dog's risk for sudden death such as number of runs of rapid
ventricular tachycardia (i.e., a lot of PVCs occurring one after another) and R-on-T
phenomenon (when one PVC starts before the preceding one completely ends.)
Cardio is a broad term for heart problems. In dogs that are 9 or older that develop
heart problems or die suddenly, can it be plain Cardio, or is it DCM, an embolism, a
stroke, or can it be just old dog heart?
The term "cardio" must have originated with breeders as that term is not used amongst
veterinary cardiologists. Instead, we use the specific diagnosis for the actual heart
disease. Sudden death in an older dog could be due to a number of different diseases,
cardiac-related or non-cardiac-related. Older dogs' hearts don't just wear out from old age. There is always an associated disease that causes problems such as disease of the heart valves which causes them to become leaky or disease of the heart muscle (DCM).
Have you used Sotalol as a med in dogs with high numbers of PVC's?
In my practice I see more Boxers with DCM than Dobes. Thus I have placed a
number of Boxers with ventricular arrhythmias on sotalol (trade name--Betapace.) I have
been happy with the results. The high cost of the drug is a limiting factor for many of my
clients. The one Dobe that I used it on died suddenly about 2 weeks later.
What role the Natural Diet for dogs plays in cardio health in dogs (versus the
commercial dog food)? I have my Dobe on the natural diet (raw meat/bones/veggies etc.)
I am assuming that you are referring to diets like the Bones And Raw Food diet.
These diets have not been proven to prevent DCM, since a dog who has the genes for it
will likely develop the disease no matter how healthy its heart is. However the diets
won't hurt the heart and they may be useful for other health issues such as allergies.
I have been giving my dogs Fish Oil from weaning on throughout their lives. Is there
any truth to the theory that fish oil can help prevent heart muscle damage caused by
Again, no supplement or diet or exercise regime has been proven to prevent DCM.
But studies have shown 2 benefits of using fish oil in dogs with DCM. It may help
decrease the incidence of sudden death from ventricular arrhythmias (this was a human
study, so it still may not apply to dogs, but we hope so) and seems to also help the severe
muscle atrophy (cardiac cachexia) that is seen in dog with severe DCM.
I bred a litter in Aug, 2000, and sold a puppy bitch to a couple in North Carolina. I
took the puppy to the vet for a health certificate exam the day before she was to be
shipped (She was 3 months old). The vet listened to her heart and identified an "irregular
heartbeat" - not a murmur. This puppy had been to the vet twice before and her heartbeat
was normal. They did an EKG at that time and the results showed several PVCs. My vet
said the puppy needed to see a Cardiologist. I notified the buyers I couldn't send them
the puppy. I took Mystic to a Cardiologist in the Chicago area about a week later. His
exam showed the same result as my ve t's - the EKG showed PVCs and her heartbeat was
irregular. He did an ultrasound and said there was no evidence of Dilated
Cardiomyopathy. The cardiologist then put a Holter on the puppy for 24 hrs. The results
showed 600 PVCs in 24 hrs. The conclusion was that the puppy does not have heart
disease - this was something she could outgrow. The Cardiologist said to have an EKG
taken six months later and then yearly. The next EKG was slightly irregular, the one
following that was normal. I have kept her because I could not let someone else deal
with this and the potential heartache of losing her at a young age. My Question is:
Have you seen a young puppy have PVCs on an EKG and Holter test, but then have
Normal EKG results a year later and go on to live a normal life with no evidence of Heart
Disease?" or, alternatively, " Have you seen a puppy like this who now at age 20
months has a normal EKG and heart rate, but later, say age 5 or 6, develop Heart
I have not personally seen a Doberman puppy with PVCs. It is certainly not typical of
DCM, especially since the PVCs are decreasing instead of getting worse. There is an
article in Kirk's Current Veterinary Therapy (p.749) that describes German Shepherds
that develop PVCs and other ventricular arrhythmias between 4 and 12 months of age.
This disease is called inherited sudden cardiac death in German Shepherds. About half
die suddenly during the first year of life. Others do not, and if they can get past 2 years
of age, their PVCs decrease and they tend to live normal lives. The theory in these dogs is
that there is an imbalance in the nerves that affect the electrical conduction in the heart
and that in some of the puppies the imbalance eventually corrects itself and the dogs
normalize. Perhaps that is what happened in your pup. I don't think there is a guarantee
though that your puppy will not develop DCM later in life, but I believe it would be a
totally separate disease than what she experienced as a puppy.
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