EN/DE: My Greyhound has an enlarged Heart / Mein Greyhound hat ein vergrößertes Herz: was soll ich tun?
Verfasst: Di 27. Nov 2018, 09:58
Deutsche Übersetzung im Anschluss
My Greyhound Has An Enlarged Heart:
What Do I Do?
Guillermo Couto, DVM, dipl. ACVIM (Internal Medicine and Oncology)
You just adopted your first ever Greyhound, after having had several dogs from other
breeds in the past. Just to make sure everything is fine, you take him to your vet for a
physical exam.
He looks GREYT, but your vet tells you that she can hear a heart murmur; so now you
are concerned? You are not quite sure what a heart murmur is, so you either ask your vet
or Dr. Google. The normal heart has 4 chambers: right atrium, right ventricle, left atrium, and left
ventricle. It resides in the anterior portion of the thorax in between the lungs. If you place
your hand flat on the left side of the thorax, near the sternum (breast bone), a bit behind
the elbow, you will be able to feel the heart (precordial impulse). Blood comes into the
right atrium from the body and exits from the right ventricle to the lungs though the
pulmonary artery. The left atrium received blood from the lungs, and the left ventricle
delivers blood to the body though the aorta, the largest artery in the body.
There are 4 valves: 2 atrioventricular valves (AV valves) that separate each
atrium from its corresponding ventricle; the left one is referred to as the mitral
valve, and the right one as the tricuspid valve. The other 2 valves are the pulmonic and aortic valves, that
are between the right ventricle and the pulmonary artery, and the left ventricle
and the aorta, respectively. Because the heart sits somewhat upright, the pulmonic and aortic valves are higher in the thorax than the AV valves; they are located in the base of the heart.
There are several phases to the “cardiac cycle” (or the way the heart works), but the main
2 are diastole (when the ventricles fill) and systole (when the ventricles empty). When
blood travels from the atria to the ventricles, or from the ventricles into the arteries, it
generates a sound. Normal dogs have 2 heart sounds (S1 and S1).
Follow the heart cycle HERE A heart murmur is an abnormal heart sound that usually results from turbulent blood flow or from blood flowing during the “wrong” phase of the cardiac cycle. Think about the way
water flows in a quiet stream, at low velocity (speed); you sit by the stream and are totally
relaxed by this mellow sound. Now you keep walking downstream and start hearing a
thunderous sound from the rapids; the high velocity of water flow results in turbulence
(swirling of the water in the rapids).
Heart murmurs are graded in intensity from 1/6 (very faint) to 6/6 (very loud); they are
designated based on what phase of the cycle they are heard best (systolic, diastolic, or
both) and where are they heard best as basilar (if they are heard up high-base of the
heart) or apical (if they are heard best near the breast bone – apex of the heart). There
are several other terms that are used to characterize the murmurs, but it may be best to
skip those! Murmurs can be physiologic (ie; normal-more on this soon) or pathologic
(due to underlying pathology, mainly valvular heart disease). For example, pups
frequently have a low intensity murmur that eventually disappears as they get older; that
is termed innocent murmur. THIS is what a heart murmur sounds like.
As most of you know, Greyhounds are the canine version of a Formula 1 car. They have
a higher red blood cells count than other dogs (the analogous to high-octane gasoline),
and a very large spleen that stores blood. The splenic capsule in the dog contains a fair
11 http://www.greyhoundhealthinitiative.org
amount of muscle fibers. When the hounds shoot out of the starting gate (or start chasing
after something), they release adrenaline (and other catecholamines) from their adrenal
glands; the adrenaline causes the spleen to contract, and “shoot” a large number of red
blood cells that were stored there into circulation. That immediately further increases the
red blood cell count. For example, a normal (non-Greyhound dog) has a hematocrit (the
percentage of red blood cells in the blood) of between 35 and 50%; a Greyhound has a
hematocrit of 50-65% at rest, and >75% after splenic contraction! A hematocrit of 75-80%
literally doubles the viscosity (“thickness”) of the blood (think honey in the refrigerator).
In addition, the left ventricle of a Greyhound has approximately 50% more blood at the
end of diastole (filling) than an equivalent size Lab, for example. In order to get the blood
out of the ventricle in the same unit of time, the blood must be expelled FASTER (as in
the rapids we just mentioned). This results in a left 1-2/6 basilar systolic murmur, normal
in most sighthound breeds, with the notable exception of Irish Wolfhounds. These
murmurs are also called “ejection” because they occur when blood is being ejected from
the ventricle; ejection murmurs are of low frequency.
How do you think Greyhounds adapted to this increase in red cell count and blood
viscosity? They developed a VERY LARGE left ventricle, the chamber that “shoots” blood
into general (non-lung) circulation! So, when you take radiographs of the thorax (chest),
the Greyhound heart is very large. Veterinarians use an objective index to determine if a
Measurements comparing heart size (L) Greyhound vs (R) Boxer
12 http://www.greyhoundhealthinitiative.org
heart is abnormally large; it is referred to as the vertebral heart score (VHS). Most dogs
have VHS of 9-10; in Greyhounds they reach over 12.
Another way to evaluate a patient’s heart is by doing an echocardiogram, which uses
ultrasonic waves that are sent out and then captured back to generate images.
Greyhound hearts are thicker (more muscle) than in other dog breeds, so a novice
cardiologist may diagnose that as an abnormality (ventricular hypertrophy). Also, the left
ventricle in Greyhounds contracts a bit different than other breeds, so it may be
interpreted as abnormal by a beginner. Now a word about stethoscopes: most of the
cardiology type units have a bell (for low frequency sounds) and a diaphragm (for high
frequency sounds). So, back to your hound; he has a heart murmur.
Your vet tells you that it is a 2/6, left basilar ejection murmur. First, that means that she is a
REALLY good vet and is using a good stethoscope (in order to hear this murmur well, vets have to use the bell – not the diaphragm – of the stethoscope)! Second, that’s GREYT news because it is a functional
murmur (ie; normal in the breed), and that means that you do not need to worry about it!
https://www.greyhoundhealthinitiative.o ... r-archive/
My Greyhound Has An Enlarged Heart:
What Do I Do?
Guillermo Couto, DVM, dipl. ACVIM (Internal Medicine and Oncology)
You just adopted your first ever Greyhound, after having had several dogs from other
breeds in the past. Just to make sure everything is fine, you take him to your vet for a
physical exam.
He looks GREYT, but your vet tells you that she can hear a heart murmur; so now you
are concerned? You are not quite sure what a heart murmur is, so you either ask your vet
or Dr. Google. The normal heart has 4 chambers: right atrium, right ventricle, left atrium, and left
ventricle. It resides in the anterior portion of the thorax in between the lungs. If you place
your hand flat on the left side of the thorax, near the sternum (breast bone), a bit behind
the elbow, you will be able to feel the heart (precordial impulse). Blood comes into the
right atrium from the body and exits from the right ventricle to the lungs though the
pulmonary artery. The left atrium received blood from the lungs, and the left ventricle
delivers blood to the body though the aorta, the largest artery in the body.
There are 4 valves: 2 atrioventricular valves (AV valves) that separate each
atrium from its corresponding ventricle; the left one is referred to as the mitral
valve, and the right one as the tricuspid valve. The other 2 valves are the pulmonic and aortic valves, that
are between the right ventricle and the pulmonary artery, and the left ventricle
and the aorta, respectively. Because the heart sits somewhat upright, the pulmonic and aortic valves are higher in the thorax than the AV valves; they are located in the base of the heart.
There are several phases to the “cardiac cycle” (or the way the heart works), but the main
2 are diastole (when the ventricles fill) and systole (when the ventricles empty). When
blood travels from the atria to the ventricles, or from the ventricles into the arteries, it
generates a sound. Normal dogs have 2 heart sounds (S1 and S1).
Follow the heart cycle HERE A heart murmur is an abnormal heart sound that usually results from turbulent blood flow or from blood flowing during the “wrong” phase of the cardiac cycle. Think about the way
water flows in a quiet stream, at low velocity (speed); you sit by the stream and are totally
relaxed by this mellow sound. Now you keep walking downstream and start hearing a
thunderous sound from the rapids; the high velocity of water flow results in turbulence
(swirling of the water in the rapids).
Heart murmurs are graded in intensity from 1/6 (very faint) to 6/6 (very loud); they are
designated based on what phase of the cycle they are heard best (systolic, diastolic, or
both) and where are they heard best as basilar (if they are heard up high-base of the
heart) or apical (if they are heard best near the breast bone – apex of the heart). There
are several other terms that are used to characterize the murmurs, but it may be best to
skip those! Murmurs can be physiologic (ie; normal-more on this soon) or pathologic
(due to underlying pathology, mainly valvular heart disease). For example, pups
frequently have a low intensity murmur that eventually disappears as they get older; that
is termed innocent murmur. THIS is what a heart murmur sounds like.
As most of you know, Greyhounds are the canine version of a Formula 1 car. They have
a higher red blood cells count than other dogs (the analogous to high-octane gasoline),
and a very large spleen that stores blood. The splenic capsule in the dog contains a fair
11 http://www.greyhoundhealthinitiative.org
amount of muscle fibers. When the hounds shoot out of the starting gate (or start chasing
after something), they release adrenaline (and other catecholamines) from their adrenal
glands; the adrenaline causes the spleen to contract, and “shoot” a large number of red
blood cells that were stored there into circulation. That immediately further increases the
red blood cell count. For example, a normal (non-Greyhound dog) has a hematocrit (the
percentage of red blood cells in the blood) of between 35 and 50%; a Greyhound has a
hematocrit of 50-65% at rest, and >75% after splenic contraction! A hematocrit of 75-80%
literally doubles the viscosity (“thickness”) of the blood (think honey in the refrigerator).
In addition, the left ventricle of a Greyhound has approximately 50% more blood at the
end of diastole (filling) than an equivalent size Lab, for example. In order to get the blood
out of the ventricle in the same unit of time, the blood must be expelled FASTER (as in
the rapids we just mentioned). This results in a left 1-2/6 basilar systolic murmur, normal
in most sighthound breeds, with the notable exception of Irish Wolfhounds. These
murmurs are also called “ejection” because they occur when blood is being ejected from
the ventricle; ejection murmurs are of low frequency.
How do you think Greyhounds adapted to this increase in red cell count and blood
viscosity? They developed a VERY LARGE left ventricle, the chamber that “shoots” blood
into general (non-lung) circulation! So, when you take radiographs of the thorax (chest),
the Greyhound heart is very large. Veterinarians use an objective index to determine if a
Measurements comparing heart size (L) Greyhound vs (R) Boxer
12 http://www.greyhoundhealthinitiative.org
heart is abnormally large; it is referred to as the vertebral heart score (VHS). Most dogs
have VHS of 9-10; in Greyhounds they reach over 12.
Another way to evaluate a patient’s heart is by doing an echocardiogram, which uses
ultrasonic waves that are sent out and then captured back to generate images.
Greyhound hearts are thicker (more muscle) than in other dog breeds, so a novice
cardiologist may diagnose that as an abnormality (ventricular hypertrophy). Also, the left
ventricle in Greyhounds contracts a bit different than other breeds, so it may be
interpreted as abnormal by a beginner. Now a word about stethoscopes: most of the
cardiology type units have a bell (for low frequency sounds) and a diaphragm (for high
frequency sounds). So, back to your hound; he has a heart murmur.
Your vet tells you that it is a 2/6, left basilar ejection murmur. First, that means that she is a
REALLY good vet and is using a good stethoscope (in order to hear this murmur well, vets have to use the bell – not the diaphragm – of the stethoscope)! Second, that’s GREYT news because it is a functional
murmur (ie; normal in the breed), and that means that you do not need to worry about it!
https://www.greyhoundhealthinitiative.o ... r-archive/