Hines DVM PhD .
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Cardiomyopathy In Cats
some non-heart -related causes of coughing, go here.
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like their owner, the hearts of our pets are often the first thing to wear out. But our pets do not develop the plaques in the blood vesicles of their heart and blood vescle blockages that we do (arteriosclerosis,
coronary artery disease) so they do not get the heart attacks
we humans experience.
Nowadays, veterinarians rely more on ultrasound and veterinary heart specialists to identify heart problems. But there was a time that the sounds your vet heard using his/her stethoscope gave important clues. In young pets, the heart murmur and rapid heart rate of anemia is distinctive. You can hear that, and others, below. Pets with a hole between heart chambers (patent ductus arteriosus) also had a distinctive "machine" murmur. Those with a narrow aorta (SAS) had another. In old pets, the mitral valve is often the first to fail. and in a few, hearts failed suddenly (cardiomyopathy). Perhaps it was your pets lack of energy, rapid heart rate and rapid respiration that caused you to bring it in for the examination.
I generated these MP3 tracks using audio and multimedia software. Please do not rely on them in any way when it concerns the health of your pet
all mammals, dogs and cats have a four-chambered heart. It consisting
of a left and right upper chambered atrium and a left and right
lower chambered ventricle.
left and right atria receive blood from the lungs and body respectively.
The left ventricle is responsible for pumping oxygen-rich blood
from the lungs out through the aorta into the body, while the
right ventricle pumps the blood through the pulmonary artery
to the lungs for oxygen.
Heart' Four Valves :
heart has 4 one-way vales to keep blood flowing in the right
direction. The valve between the left atrium and ventricle is
the mitral valve. The one between the right atrium and
ventricle is the tricuspid valve. The one regulating
blood going into the aorta is the aortic valve and the
one regulating blood going to the lungs is the pulmonic valve.
mitral valve is the most fragile of the four valves in your
pet's heart. In dogs, it is often the first one to wear out.
Signs Would I See If My Pet Had A Heart Problem ?
first sign that most owners notice is a cough. this is because
enlarged, failing hearts allow fluid to back up into the lungs
and also press on the wind pipe.
signs you may notice in your pet are tiredness, rapid breathing,
poor appetite, an enlarged tummy, pale or bluish gums, and a
rapid, weak pulse. Fainting is less common.
Might My Veterinarian Hear Through A Stethoscope ?
of these pets have heart murmurs. Heart murmurs come about when
a passage through the heart becomes too narrow or too wide.
In middle aged or older adult cats and dogs, this usually means
that a valve is not working properly. It may not be closing
sufficiently or it may not be opening sufficiently. In younger
pets, a murmur might mean that the heart did not develop properly.
pets develop heart murmurs because their blood is too thin -
not because of an abnormal heart.
rhythm of a weakened heart also changes. But unlike us, frequent
changes in the heart rate of relaxed dogs is normal.
Tests Might My Veterinarian Perform ?
your veterinarian is suspicious that your dog might have a heart
problem, the first test we traditionally do is an x-ray. If
the x-ray shows an enlarged heart, your veterinarian may be
satisfied with that and begin treatment.
it is unclear if the heart is enlarged or if the heart is even
the source of your pet's problems, a proBNP
Test might be ordered. This test is especially
useful in cats when we are not sure if the cat has a lung problem,
asthma or a heart problem.
tests that your veterinarian or a cardiac specialist might perform
are echocardiograph (doppler ultrasound) to see the heart perform
in real time, and an EKG to check if the electrical system of
the heart is functioning normally.
Are Some Of The Effects Of A Failing Heart ?
dogs, the valves are often the first heart structures that are
affected. Heart disease in cats usually involves the entire
heart muscle and not just the valves.
let us know early that there is a problem. But we are often
unaware that our cat has a heart problem until its heart is
well on its way to failing. Often the only signs in your cat
are weight loss, and difficulty breathing. Cats are more likely
to make asthmatic-like sounds than to have a hacking cough.
with this form of heart disease do not survive long. Signs of
all forms of heart disease in cats are quite similar and your
veterinarians will not be able to tell one from the other without
some sophisticated tests.
all cases of heart disease in dogs and cats, as the circulatory
system fails, the kidneys liver and all other organs are flooded
with stagnant blood and work inefficiently. This is because
they do not get the oxygen they need.
Problems That Affect Both Dogs And Cats :
heart is like your car's motor. If one part goes out, it is
not long before it causes another part to fail. So in reality,
most actual cases of heart disease are a combination of several
problems. The normal heart has a very precise shape. As its
shape expands and becomes more rounded, the heart is not able
to perform any of its tasks well.
Heart Failure (CHF) :
heart failure is an enlarged heart. No mater what the underlying
heart problem is, CHF is usually the end result.
occurs when the heart is unable to meet the circulatory demands
of the body. Many things can cause the heart to be faced with
increased back pressure and decreased effectiveness as a pump.
Valvular defects, tumors, heartworms, heart beat abnormalities,
and damaged to the muscle itself all cause the heart to enlarge
and blood to pool in the organs and lungs. The net effect of
all this is called congestive heart failure.
pets with CHF have an enlarged heart. As the disease progresses,
the normal triangular shape of the heart becomes rounded. This
is very noticeable on an x-ray. An x-ray or a cardiac ultrasound
is the way your veterinarian will confirm CHF.
CHF is a common human problem, drugs are constantly being developing
and refining to treat it. These human medications work quite
well in our pets too. So your veterinarian may be using a drug
I have not mentioned. This is particularly the case if you visit
a veterinary cardiologist. However, it is uncertain if these
newer human medications extend the life of your pet any more
than those that are more commonly used by your local veterinarian.
usually treat CHF with several medication groups at once :
remove as much pooled fluids and blood as we can with drugs
Once these fluids are removed from your pet's lungs, the cough
should go away or be much better. The big pot-belly associated
with CHF should also go away. The most commonly used diuretics
is furosemide (Lasix).
furosemide will no longer remove enough fluid from your pet,
we often add a second diuretic called spironolactone.
not be surprised when your pet drinks and urinates more on those
increase the diameter of blood vessels throughout the body with
vasodilator drugs so the heart does not have to work as hard.
of the medicines of this group are called ACE
inhibitors. The most common ones in this group are enalapril
(Enacard) and Lisinopril (Prinivil).
making it easier for blood to flow through blood vessels, ACE
inhibitors help decrease your pet's heart rate, and help preserve
the heart's remaining strength. The most common side effect
of these drugs is lack of appetite and vomiting. If that occurs,
the dose needs to be adjusted.
are an exciting group of drugs that seem to definitely extend
the lives of dogs with CHF. The one most commonly used is called
(Vetmedin). It increases the amount of blood that the weakened
heart can pump by giving more strength to its muscle fibers.
It also opens up blood vessels throughout the body so the heart
doesn't have to work as hard. A study found that dogs receiving
pimobendan and furosemide lived
9 months longer than those receiving only enalpril and
furosemide. It has been used in cats, although it is not licensed
for that species.
group of drugs we used when diuretics and ACE inhibitors were
not enough are called Positive ionotrophic agents. A
drug in this group that was quite popular is digoxin.
Because of its potent side effects and the limited length of
time pets will survive while on it, I rarely prescribe it. It
is a medicine of last resort.
heart has an electrical wiring system to coordinate it's contractions.
When the heart is damaged, this system may fail. We call the
abnormal beat rhythm a cardiac arrhythmia.
of the drugs used to control arrhythmias are
propranolol (Inderal) procainamide (Pronestyl), and tocainide
Proven Medications :
veterinarians suggest pets with heart disease consume a low
sodium diet. This is a particularly good idea if your pet also
has elevated blood pressure or retained fluid. We do not know
if low sodium diets are as beneficial to pets as they are to
veterinarians prescribe coenzyme Q because of its beneficial
effects in people with dilated cardiomyopathy.
fatty acids are high in fish oil. In people, there is some
evidence that omega-3 supplements might reduce the risk
of heart attacks and strokes. Based on this, some veterinarians
suggest that dogs with heart problems also receive them.
is involved in the process by which the heart muscle converts
fats into energy. There is some
data that L-carnitine supplements help people who have heart
disease. Whether or not it helps pets, we do not know.
is a small group of dogs and cats that develop heart disease
due to a deficiency in the amino acid, Taurine. Since it is
non-toxic, some veterinarians suggest a taurine supplement for
all their cardiac patients.
Things You Can Do :
your pet's weight optimal, feed a name brand high quality commercial diet or prepare one at home. (ref)
exercising your pet, keep activity to a level somewhat less than
what it would take to cause your pet to breath heavily, pant
or elevate its heart rate. Don't give up short walks until you
absolutely must. Dogs and cats benefit physically and mentally
Disease Of Dogs And Cats :
Certain breeds of dogs, particularly toy breeds, have a tendency
to develop scaring heart valve problems or endocardiosis. This
is the most common form of heart disease in dogs and the rarest
scaring of the mitral valves is also quite common in all old
dogs. The mitral valve divides the lower and upper left chambers
of the heart. It's constant hard work may cause it to fail to
completely close and open. Sixty percent of dogs over 8 years
old have some degree of this problem. But less than half the
dogs with this condition have any symptoms you will notice.
veterinarians have noticed that small breeds of dogs that eat
soft food and table scraps eventually develop chronic mouth
infections or periodontal disease. It is very common for these
pets to also have a heart murmur related to their mitral valve.
We think that bacteria move from the infected gums through the
blood and attach to the heart valves to cause a condition called
endocarditis that eventually scar the heart valves.
the mitral valve wears out, its two flaps become blunted, shriveled
and scarred so that they do not open or close properly. When
this happens, blood does not flow in the normal pattern but
leaks back in to the atrium or ventricle.
time, increased back pressure causes one or more chambers of
the heart to enlarge. As the chambers of the heart enlarge they
press on the windpipe resulting in a dry, hacking cough. The
enlarged heart also stretches the nerve fibers that control
heart rhythm resulting in abnormal beats or arrhythmias. As
blood backs up, it pools in the lungs as edema that makes the
cough even worse. Particularly when the pet is lying down or
Heart Development :
Dogs and cats are sometimes born with abnormal hearts. We call
this congenital heart disease.
Stenosis (SAS) :
problem is most common in big dogs (Rotties,
Boxers, Newfoundlands, Goldens, Great Danes etc.) It
is the most common inherited heart disease in large dogs.
subaoritic stenosis the puppy is born with an abnormally narrow
passage way leading from the heart to the aorta. It comes in
all degrees, from a very mild case, requiring no treatment to
a life-endangering problem.
you take a puppy to the vet for his first vaccinations, the
veterinarian should listen to the puppy's heart. In a puppy
with SAS, there will usually be a heart murmur over chest near
the left base of the heart. If the puppy is not severely anemic
with hookworms, then SAS is the most common cause of the murmur.
This is how most cases of SAS are first diagnosed. Not every
puppy with a heart murmur has SAS. Puppies often outgrow heart
murmurs without our really knowing what caused them in the first
place. Only some complicated tests can tell which murmur is
important. But if your puppy still has a murmur when it is 6
months old, SAS becomes likely.
a puppy has a significant degree of SAS, its heart has to work
harder to force the blood through the narrow area just below
the aortic valve. With time, the heart muscles get thicker due
to the extra effort. As the walls thicken, the full heart holds
less and less blood and needs more and more oxygen. Eventually,
the heart begins to fail. Unlike older dogs with CHF, SAS puppies
often die suddenly when clots form in the heart muscle or its
electrical system fails.
parent of an SAS puppy should ever be bred again.
Signs Would I See In A Puppy ?
often, you will see no signs at all in your puppy. But as time
goes by and the puppy's heart muscles thicken, problems in the
electrical system of the heart can cause fainting or unexpected
Tests Might My Veterinarian Perform ?
decide how serious a heart murmur really is, your pet needs
to have an echocardiograpy (doppler ultrasound) performed by
a veterinarian experienced in interpreting the results. An x-ray
and an EKG will also be required to see how much damage has
Are The Treatment Choices I Have ?
most popular drugs used to treat SAS are known as beta
blockers (ß-blockers). The most commonly used ones
are Propranolol (Inderal) and atenolol (Tenormin). Beta blockers
reduce heart rate, help control abnormal heart rhythm and reduce
blood pressure. They are proven in their ability to extend the
lives of dogs with SAS.
heart surgery to correct this problem in dogs has not been as
successful as one might hope. Dogs that have had the surgery,
live about as long as dogs that just receive medicine.
technique is similar to balloon angioplasties that are done
to dilate blocked coronary arteries in people. A catheter is
threaded into the heart and a balloon is expanded in the narrowed
area of the heart. So far, this technique has not led to increased
Long Will A Puppy With Heart Problems Live ?
is very difficult to predict. They younger the puppy is when
the problem is first noticed, and the louder the heart murmur,
the bleaker the outlook. Most dogs with the typical signs of
SAS do not live over 3 years without medication.
cardiac work-up at a regional veterinary center that includes
all the diagnostic tests, might give you more insight. But all
pets with this condition can die suddenly - and often do.
Dilated Cardiomyopathy :
This problem was due to a deficiency in an amino acid, taurine.
Now that we know that cats must have sufficient taurine in their
diet, all major brands of cat food have adequate taurine levels.
deficiency caused the heart muscle to loose its strength. Cats
with this problem lost weight and had difficulty breathing.
Blood clots often formed in the hearts of these cats.
A second, genetic form of the disease occurs in Siamese, Burmese
and Abyssinian cats. We treat this condition with the same medicines
that increase the hearts efficiency and decrease pooled fluid
in the lungs. We also give them drugs to reestablish their normal
heart rhythm. Many veterinarians include a taurine supplement
in any heart condition in cats. A similar heart disease can
also occur secondary to an over-active thyroid gland. Cats with
this problem will not live very long.
Cardiomyopathy Of Cats :
In this disease the walls of the heart thicken, leading to inefficient
pumping of blood. Blood pressure rises and fluid accumulates
in the lungs. Eventually the chambers of the heart enlarge and
abnormal heart rhythms occur. Signs of this disease are labored
breathing, rapid heart rate, heart murmurs, weakness, collapse
and death. Rare heart valvular disease, hyperthyroidism and
asthma can mimic hypertrophic cardiomyopathy. We diagnose this
disease with x-rays electrocardiograms (EKG = ECG) and cardiac
treat the disease with low salt diets, diuretics, aspirin to
prevent blood clots, and medications such as diltiazem and atenelol
to stabilize blood pressure and heart rate. Do not give aspirin
to your cat without veterinary supervision - cats do not handle
aspirin well and Never give them Tylenol.
Restrictive Cardiomyopathy Of Cats :
In this condition localized scarring of the heart muscle prevents
the normal beating of the heart. This leads to an enlarged,
weak heart and congestive heart failure. Signs of the disease
are poor appetite, weight loss and difficult respiration. Sometimes
blood clots that cause paralysis of the limbs occur. X-rays,
EKG and ultrasound all show atrial enlargement. We treat these
cats with calcium channel blockers such as diltiziam, diuretics
such as furosemide and low doses of aspirin. Aspirin must
be used with extreme caution in cats - if at all . Do so only under the
supervision of a veterinarian. Low sodium diets might also help
if the pet will eat them. If we are fortunate, cats with this
disease live about a year.
Corticosteroid-related Congestive Heart Failure in Cats
In 2004, the University of Minnesota Veterinary Center noticed an occasional link between heart failure and a recent dose of a number of corticosteroid medications in their feline patients (particularly with injectable methyl prednisolone acetate = Depomedrol aka "Depo"). Of the 160 cats with heart failure that passed through their clinic between 1992 and 2001, at least 8% that developed congestive heart failure had received those medications within the 1-3 weeks preceding their developing heart problem symptoms. This unique form of heart disease often resolved itself with time. Corticosteroids are often given to cats with respiratory problems that are believed to be asthmatic. In other cases , they were given for allergic skin conditions or as appetite stimulants. (ref)
Cardiomyopathy Of Dogs :
In this condition, as in cats, the heart chambers enlarge to
the point where they can no longer pump blood efficiently. It
is most common in large breeds of dogs and rare in small breeds.
Doberman Pinschers, Great Danes, German Shepherds and Labrador
Retrievers are particularly at risk. The disease is most common
in middle-aged dogs, especially males. Usually the cause is
unknown. However, we think that taurine deficiencies, parvovirus
and the use of adriamycin have all caused the disease.
overly-stretched heart muscle that occurs in this disease is
an inefficient pump. Signs of the disease are those of congestive
heart failure: difficult breathing, weakness, coughing and fluid
enlargement of the abdomen. These dogs may need oxygen until
medicines have an opportunity to work. Low salt diets as well
as supplements that contain taurine, L-carnitine (carnatine)
and coenzyme Q may also be helpful. Dogs do not survive long
with this condition.
Cardiomyopathy Of Dogs :
This disease is quite rare. As in cats, the muscles of the heart
thicken and become inefficient at pumping blood. The signs of
the disease are the signs of congestive heart failure e.g. difficulty
breathing, coughing, heart murmurs and exercise intolerance.
How Will I Know If The Medications My Veterinarian Gives Me Are Working ?
most common reason pets with heart problems come to see veterinarians
is because of breathing problems. These pets tend to breath
faster than they should and they tend to be congested. One can
have complicated tests performed to evaluate if the medications
are doing their job, but monitoring your pet's breathing rate
and freedom from congestion at home is just as accurate - perhaps
more so. If the medications are working, your pet will breath
slower and easier when it is at rest. If you want to confirm
your decision about its progress based on its respiration, do
so by having your vet run occasional proBNP tests (or Cardio-BNP if your pet is a dog) to confirm
their level is dropping or holding steady. You can read an article
that confirms that here.