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5 Common Cardiovascular Conditions in Canine Athletes
By Kim Rain
Published: 12/01/2021, edited: 12/01/2021
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Overview
All dogs love to play, but some dogs excel at it! Canine
athletes lead vigorous and exciting lives, whether competing in agility, dock jumping or disc
contests, or spending their time herding and entering field
trails. These athletics pups can also be found assisting police, military or
emergency personnel.
Being an athlete comes with a lot of work, and just like in
humans, a dog’s body can be affected by engaging in strenuous training, work
and play. Human and dog athletes alike undergo cardiac remodeling wherein the
heart’s structure can change over time to accommodate the new needs of the
body. While this is a normal process, sometimes the remodeling can cause a
problem, such as when an area of the heart muscle thickens, which can in turn
cause ventricle narrowing and restrict blood flow.
While exercise does keep a body healthy, too much can be
harmful. Supplements and a healthy diet can support an active body, but always
consult your veterinarian when making any changes or adding new elements to
your dog’s regimen.
Left ventricle hypertrophy
LVH occurs when the left ventricle wall of the heart
thickens in response to the heart needing to work harder than usual, which in
turn decreases blood flow through that chamber. This condition can affect
athletes due to their consistent training and exercise routines that requires
the heart beat faster and harder to keep pumping blood to where the body needs
it.
Symptoms
While LVH is a condition, it can also be a symptom of, or
caused by, other heart conditions, and may be accompanied by other signs that
can help point to a cause or indicate heart disease. LVH can also be a
predictor of sudden cardiac death.
- Shortness of breath
- Dizziness
- Fainting
- Fatigue
- Rapid heartbeat
- Chest pain
Causes
- Continuous, strenuous exercise
- High blood pressure
- Cardiac remodeling
- Dilated cardiomyopathy
- Hypertrophic cardiomyopathy
- Valve disease
- Congenital heart disease
- Pregnancy
Diagnosis
Be sure to relate any and all symptoms you’ve noticed in
your dog to your veterinarian, along with your dog’s activity level, and how
long they’ve been engaged in vigorous exercise. After a physical exam that will
include listening to your dog’s heart and lungs, your veterinarian may order
several tests to help with the diagnosis.
Many times, LVH is first seen on an ECG. Imaging tests
including X-rays, ultrasounds and an echocardiogram are used to look that any
thickening or other abnormalities of the heart. Blood tests can alert to high
levels of certain proteins that can signal heart failure, while a urinalysis can
provide further insight.
Treatment
For a left ventricle hypertrophy that is attributed to an
athletic lifestyle, often no treatment is required, but you may need to stop
exercising your dog for several months.
Medications may be given for several different reasons, such
as ACE inhibitors to control blood pressure, diuretics to reduce fluid
retention, vasodilators to widen the arteries and veins, digitalis glycosides or
pimobendane.
Average cost of treatment: $500 - $6,000.
Hypertrophic cardiomyopathy
This rare cardiac disease is characterized by the thickening
of one or more areas of the heart. In HCM, generally the lower chambers, or ventricles,
are affected, and the condition may be a cause or result of left ventricle
hypertrophy. The septum, or the wall that separates the right and left
ventricles in the heart, can also be thickened, reducing blood flow from the
left ventricle. In athletes, HCM is directly caused by strenuous and continuous
exercise.
HCM can lead to other heart conditions, including arrhythmias,
aortic
thromboembolism, blood
clots, and decreased blood flow. This heart condition can also cause muscle
cells to die which may scar and lead to fibrosis.
Symptoms
Hypertrophic
cardiomyopathy can be quiet and show no symptoms, but dogs that are affected often
have signs.
- Coughing
- Exercise intolerance
- Rapid breathing
- Fainting
- Collapse
- Heart murmurs
Causes
- Repetitive, strenuous exercise
- Left ventricle hypertrophy
- Genetics
- High blood pressure
- Hyperthyroidism
- Cancer
- Amyloidosis
- Inflammation
Diagnosis
After
a physical exam, if your veterinarian suspects HCM or another health issue,
they will order imaging tests. These can include an echocardiogram, X-rays and
ultrasounds to look at heart function and thickened areas. An ECG is also
ordered to look at the heart beat. Blood testing, a blood pressure assessment,
and even a urinalysis and thyroid testing can be done. In some cases, a BNP
test is recommended that looks for proteins in the blood that may indicate
heart failure.
Treatment
There
is no general treatment for HCM, and no medication has been proven to slow or
stop the progression of the condition. Dogs with this condition are at risk of
congestive heart failure and sudden death.
Medications
may be given to treat some of the symptoms, or complications associated with
HCM. These can include diuretics to decrease fluid in the body, ACE inhibitors
to lower blood pressure, and drugs to prevent blood clots, increase heart
contractability, and block calcium channels. Digitalis glycosides and pimobendan
may also be prescribed.
Monitoring
your dog and re-testing every 3 to 4 months allows you and your veterinarian to
watch the disease’s progress and treat new symptoms that may develop.
Average cost of treatment: $500 - $6,000.
Arrhythmia
An arrhythmia is
an irregular heartbeat due to abnormal electrical activity in the heart muscle.
Normally, a regular heartbeat increases during activity and decreases during
rest at a normal and predictable pace. While this is the same in dogs as in
humans, a dog’s heartbeat does beat faster than ours, so discovering an
irregular heartbeat can be difficult.
Dogs who exercise or train regularly can sometimes
experience an irregular heartbeat due to the excessive activity. Canine
athletes are particularly susceptible to bradycardia, or an irregularly slow
heartbeat. For dogs, this would be a heart that beats 40 times or less per
minute.
Symptoms
- Abnormally fast heartbeat
- Abnormally slow heartbeat
- Moving slow
- Difficulty breathing
- Fatigue
- Weakness
- Collapsing
- Coughing
- Dizziness
- Decreased ability to exercise
- Seizures
- Loss of consciousness
Causes
There
are several kinds of arrhythmias that can affect dogs, and each can be caused
by various conditions.
- Genetics
- Atrial fibrillation
- Atrioventricular block
- Congestive heart failure
- Heart disease
- Cardiomyopathy
- Imbalance of electrolytes
- Systemic disorders
- Drug overdose
- Age
Diagnosis
A
lot goes into diagnosing an irregular heartbeat, as there are many conditions
that could cause it. First, your veterinarian will conduct a thorough physical
exam, and listen to the heart for the heartbeat. Relate all symptoms you have
noticed, including changes in heartbeat during different activities, and
changes in appetite, activity levels and mood in your dog.
Usually,
your vet will do several kinds of tests to help narrow down a cause, including
a full blood panel, a urinalysis, and testing for electrolyte balance. Then,
X-rays and ultrasounds of the chest will be taken to look for an enlarged heart
or other abnormalities, an echocardiogram performed, and an ECG to more closely
listen to the heart rate and discover is there are any premature contractions.
In some cases, an atropine response test will be performed.
If
the irregular heartbeat is not present during the vet visit, you may be sent
home with a Holter monitor that records your dog’s heartbeat for 24 hours for
the vet to review.
Treatment
Treatment
of an irregular heartbeat will depend on whether the beat is too fast or too
slow, and the underlying reason for the abnormality. Drug overdoses are treated
as emergencies in the hospital, and management after recovery will generally
dictate that the drug will no longer be used.
Several medications can be prescribed to increase or lower
the heartrate artificially, including cardiac glycosides such as Dioxin,
calcium-channel blockers such as Diltiazem, anticholinergics in the case of
bradycardia such as Atropine
or Propantheline, antiarrhythmics such as Mexiletine or Sotalol, or xanthines
such as Theophylline.
Any
breathing difficulties will be considered emergencies and treated with oxygen
and IV fluids. Often, heart monitoring will continue after treatment to see if
treatment is working.
Average cost of treatment: $300 - $6,500.
Systolic heart murmur
A heart murmur is an abnormal sound from the heart produced
by the turbulent flow of blood through it. In athletes, murmurs can be produced
due to the increased blood flow that strenuous activity requires. A systolic
murmur is heard when the blood rushes into a chamber, while a diastole murmur
sounds as the blood rushes out.
Symptoms
Often, only a veterinarian will discover a heart murmur
during a routine exam, as they are usually only heard through a stethoscope.
- Heart murmurs
- Vibration in chest accompanying heart murmur
Causes
- Increased blood flow through heart due to strenuous activity
- Heart abnormality, including thickening
- Narrowing of arteries
- Valve defect
Diagnosis
During a routine exam, your veterinarian may discover a
heart murmur while listening to your dog’s heart through a stethoscope. Your
vet will listen closely to determine if it is a systolic or diastolic murmur,
how often it occurs and whether or not the sound increases or decreases in
intensity from the start of the murmur. The murmur is then graded from very
quiet to loud enough that it is accompanied with a vibration felt on the chest,
Grades I through VI.
Next, MRIs, X-rays, CT scans and ultrasounds can be used to
see what is happening with the heart and help diagnose the cause that led to
the murmur. Often, a heart murmur is an
indication of an underlying heart condition.
Treatment
Treatment of heart murmurs depend on the underlying
condition causing the murmur. In some cases, treatment is not necessary, but
monitoring will likely continue. Surgery to correct a valve defect may be
recommended.
Medications
may be given for different conditions relating to cardiac thickening or
enlarging, such as ACE inhibitors to control blood pressure, diuretics to reduce
fluid retention, or digitalis glycosides or pimobendane. For constricted
or narrowed arteries, vasodilators
to widen the arteries and veins may be given.
Average cost of treatment: $1,800 - $5,000.
Athletic heart syndrome
Athletic heart syndrome is the combination of symptoms that
have developed through the rigorous training and exercise routines of athletes,
both human and canine. This condition is common to endurance athletes, and has
been documented in working sled dogs.
Symptoms
The signs of athletic heart syndrome are those of the
conditions it includes, i.e., left and right ventricular hypertrophy, bradycardia,
sinus arrhythmia, and heart murmurs and gallops.
- Difficulty breathing
- Dizziness
- Fainting
- Lethargy
- Moving slow
- Rapid or slow heartbeat
- Weakness
- Inability to exercise
- Collapse
- Seizures
- Chest pain
- Heart murmurs
- Vibration in chest accompanying heart murmur
Causes
- Continuous, vigorous exercise
- Cardiac remodeling
- Genetics
Diagnosis
Since this condition affects athletes specifically, be sure
to tell your vet about your dog’s activity, training and any work or competitions,
including how long and how often they’ve been doing it, and how the symptoms have
progressed.
To diagnose athletic heart syndrome, your veterinarian will
start by performing a physical exam and listen to the heart. The presence of
murmurs and an irregular heartbeat will immediately alert them to a problem.
This is usually followed up by an ECG, and various imaging tests to visually
see any heart thickening, including X-rays, CT scans, MRIs and ultrasounds. An
echocardiogram is performed, and various blood panels are generally run. A
urinalysis and other testing may occur to rule other conditions out.
Once your veterinarian has the main components that make up
athletic heart syndrome, namely, ventricular hypertrophy, bradycardia,
sinus arrhythmia, and heart murmurs, along with a history of vigorous activity,
this condition can be diagnosed.
Treatment
Depending on your dog’s particular condition, your vet may
recommend halting activity for several months to allow the body to readjust and
reduce the factors that created athletic heart syndrome. If allowed to
continued unchecked, this condition can lead to sudden cardiac failure.
Other treatments center on treating each symptom, such as
medications for regulating blood pressure, reducing fluid retention, and
helping the heart beat and function properly. Monitoring should continue with
results dictating further treatments as necessary.
Average cost of treatment: $500 - $6,500.
Cardiovascular conditions can be expensive to treat. If you
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