Why does my dog need a pacemaker?
Most dogs that require a pacemaker have slow heart rates and
clinical signs of exercise intolerance, collapse or fainting and
What happens if my dog has a slow heart rate but we decide not
to put in a pacemaker?
Clinical signs of exercise intolerance, collapse and heart
failure may persist or worsen without pacemaker implantation.
Occasionally, the heart will stop beating resulting in sudden
How is a pacemaker placed?
The pacemaker is typically placed through the jugular vein in
the right side of the neck. Occasionally, the pacemaker may be
placed in the abdomen if your dog has skin disease or any other
disease that prevents placement in the neck. The decision on where
to place the pacemaker will be decided by the doctor caring for
your dog. Some dogs need one pacing lead, while others will require
multiple pacing leads depending on the heart problem.
Is my dog too old for a pacemaker?
Many dogs that require a pacemaker are older. Often times,
owners may attribute slowing down to aging when, in fact, it is due
to a slow heart rate. Important diseases of other organ systems,
however, may preclude placement of a pacemaker.
How often are recheck examinations recommended?
Rechecks to evaluate pacemaker function and battery life should
be performed one month following pacemaker placement and then every
six months, ideally at Texas A&M. Additional rechecks are
recommended earlier if your dog exhibits weakness or collapses.
Will my dog need heart medication?
Most dogs will not require medication following pacemaker
placement. However, concurrent or underlying disease may
necessitate additional medical therapy.
What is needed once my dog is home from surgery?
It is important that the incision be kept clean and dry.
Activity should be kept to a minimum for 30 days until the incision
has completely healed, and to minimize the chance of pacemaker lead
dislodgement. A special diet is not required unless recommended by
the doctor caring for your dog. If your dog's pacemaker was placed
in the neck, a harness should be used instead of a collar to walk
your dog to prevent unnecessary pulling on the pacemaker.
What things should dogs with pacemakers avoid?
Microwaves do not present a danger to your dog. If your dog has
a pacemaker and requires a Magnetic Resonance Imaging (MRI) or
Computed Tomography (CT) scan, notify your veterinarian.
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Patent Ductus Arteriosus (PDA)
What is a Patent Ductus Arteriosus?
Patent ductus arteriosus (PDA) is one of the most common
congenital heart defects in dogs. PDA occurs more frequently in
certain breeds of dogs including poodles, Shetland sheepdogs,
collies, German shepherds, Maltese, Bichon Frise, Chihuahuas,
Pomeranians and Newfoundlands. It is present more commonly in
females than males.
The ductus arteriosus is a blood vessel that is normally present
in a puppy before it is born. At birth or within a few days of
birth, the ductus arteriosus should close allowing blood to begin
flowing through the lungs to pick up oxygen. If the ductus
arteriosus does not close, it results in an abnormal communication
between the two largest vessels in the heart, the aorta and the
pulmonary artery. This causes an increase in the amount of blood
that flows through the left side of the heart, resulting in extra
work for the left side of the heart. The increased volume of blood
and extra work can cause heart failure.
How is a PDA diagnosed?
Blood flowing through the PDA causes a characteristic heart
murmur typically heard at your puppy's first visit to the
veterinarian. X-rays of the chest may show heart enlargement. An
echocardiogram is required to definitively diagnose PDA.
What are the clinical signs of a PDA?
Exercise intolerance, cough and breathing difficulty are the
most common signs. Many dogs have no clinical signs at the time of
What are the treatment options for a PDA?
Interventional Catheterization Procedures:
With these minimally-invasive procedures, a small incision is made
in the right inner-thigh and a catheter is placed into an artery in
the leg. The catheter is advanced into the aorta and PDA. A dye
injection is made (angiogram) allowing precise determination of the
size and shape of the PDA. Then a device (coil, plug, or canine
duct occluder) is placed into the PDA to stop blood flow.
Occasionally, the PDA is a shape (short or tubular) that precludes
the use of interventional catheterization procedures.
This procedure is performed by making an incision in the left side
of the chest between the ribs. The heart is exposed, and the PDA is
tied off to stop all abnormal blood flow. Surgery patients require
pain medication after surgery, and may need an extra day of
Both procedures typically take an average of two hours to
perform. Dogs that present clinical signs of heart failure
(breathing difficulty, weakness) are at a greater risk of having
complications with either procedure.
What happens if the PDA is not fixed?
If not corrected, dogs with PDA have a 60% mortality in the
first year. Occasionally, adult dogs are diagnosed with a PDA that
is small and only caused minimal changes to the heart.
Are there any complications with either procedure?
Both procedures are typically safe (98% survival), but
complications can arise. Complications include rupture and
excessive bleeding of the PDA or artery in the leg, incomplete
closure of the PDA, device embolization to the lungs, puncture of
the heart or vessels and residual air in the thoracic cavity
necessitating placement of chest tubes.
Does a dog's size make a difference as to which procedure can
A dog's size must be taken into consideration when determining
which procedure to perform. Dogs must weigh at least 4-5 pounds in
order to perform an interventional catheterization procedure.
Occasionally, a small dog can wait until it is large enough to
undergo an interventional catheterization procedure. This is only
considered if the PDA is thought to be small, and there is no
clinical evidence of important heart changes.
How do interventional catheterization procedures work?
During these procedures, one of several different devices is
deployed in the PDA resulting in physical obstruction of the PDA.
The device is left in place for the duration of the patient's life,
and has not been associated with any long-term complications.
What special care is needed once my dog is home from
It is important that the incision(s) be kept clean and dry. Do
not allow your dog to lick or chew at the incisions. An Elizabethan
collar should be placed around the neck to prevent licking or
chewing, especially if the dog is going to be left alone. Do not
allow your dog to play and rough house until the incision(s) are
completely healed. This takes about 10-14 days. The sutures are
typically buried beneath the skin, and will dissolve on their own.
Occasionally, they will need to be removed by your veterinarian. A
special diet is not required unless indicated by your doctor.
Will my dog's heart return to normal?
In most cases, if clinical signs were present, they improve
dramatically once the PDA is closed. The heart may return to normal
size with time , but enlarged hearts may not completely return to
normal. A recheck echocardiogram of the heart is recommended 1-3
months after surgery to monitor heart size and function.
Why is there a heart murmur present after surgery?
In dogs with big hearts, the mitral valve leaflets in the left
side of the heart stretch apart causing a leak called mitral
regurgitation. This will result in a murmur that is often heard
even after the PDA is closed, and that may go away with time as the
heart returns to normal size. In a small number of patients, this
type of murmur may persist indefinitely.
Should a dog with a PDA be used for breeding purposes?
PDA is considered a heritable disease that can be passed to
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Pulmonic Stenosis (PS)
What is pulmonic stenosis?
Pulmonic stenosis (PS) is a congenital heart defect commonly
found in certain dog breeds including the English and French
bulldog, boxer, miniature schnauzer, West Highland white terrier,
Chihuahua and mastiff.
Normally, the pulmonic valves have three thin leaflets of tissue
which close to form a tight seal. When blood is pumped out of the
right side of the heart, the three leaflets move out of the way to
allow the blood to pass.
The most common form of pulmonic stenosis occurs when the three
leaflets are thickened and fused along their borders causing an
obstruction to normal blood flow. In some dogs, the ring of tissue
surrounding the pulmonic valve leaflets is too narrow. This is
called annular hypoplasia.
Rarely, dogs will have a narrowing in the pulmonary artery above
the pulmonic valve leaflets called supravalvular pulmonic
How is pulmonic stenosis diagnosed?
Dogs with pulmonic stenosis have a characteristic murmur that is
typically heard at your puppy's first visit to the veterinarian.
The obstruction of blood flow through the abnormal valve leaflets
or narrowed tissue causes the murmur. X-rays and ultrasound
(echocardiogram) show enlargement of the right side of the heart.
An echocardiogram is required to diagnose the severity of pulmonic
stenosis. Dogs with mild to moderate pulmonic stenosis do not
typically develop clinical signs or require an intervention.
What are the clinical signs?
Commonly, puppies with pulmonic stenosis will not have any
clinical signs. Some dogs have exercise intolerance. Collapse, also
called syncope, may occur with excitement or exercise, and is
similar to fainting. In severe cases, the right side of the heart
will fail causing the abdomen to become distended with fluid.
What are the treatment options for pulmonic stenosis?
Dogs with severe pulmonic stenosis and clinical signs may
benefit from an interventional procedure.
This procedure is performed in dogs with valvular pulmonic
stenosis. First, a catheter is placed into the jugular vein in the
neck. The catheter is directed into the right side of the heart and
a contrast study (angiogram) is performed to determine the location
and severity of the pulmonic stenosis. A catheter with a balloon on
the end is then placed across the pulmonic valve leaflets, and the
balloon is inflated to open the valve.
Surgical repair of pulmonic stenosis can be performed in select
dogs with supravalvular pulmonic stenosis or annular hypoplasia. It
is only available at hospitals with personnel trained to perform
cardiac surgery; some centers perform this with inflow
Can pulmonic stenosis increase in severity in my dog?
The severity of pulmonic stenosis can increase until a dog
reaches mature body weight.
Will my dog need heart medication?
Medications are typically prescribed following a balloon
valvuloplasty. A beta blocker is prescribed for at least six months
following the procedure to assist the heart in returning to normal
size and to maintain the heart rate within a normal range. Some
dogs may require additional heart medications or life-long
Should a dog with a pulmonic stenosis be used for breeding
Pulmonic stenosis is considered a heritable disease that can be
passed to puppies.
What special care is needed once my dog is home after balloon
It is important that the small incision on the neck be kept
clean and dry. A special diet is not required. Exercise should be
restricted until the incision is healed.
Why does my dog still have a heart murmur after balloon
The heart murmur is created by turbulent blood flowing through
the abnormal pulmonic valve leaflets. Even with a successful
balloon valvuloplasty, blood flow will not be completely normal
through the pulmonic valve leaflets. Most dogs will have a murmur
even after successful balloon valvuloplasty.
Will my dog's heart return to normal after balloon
In most cases, clinical signs dramatically improve after
surgery. It takes much longer for the heart to return to normal,
and, in fact, most changes remain permanently. A recheck
echocardiogram is recommended 3-6 months after balloon
valvuloplasty. Rechecks may be repeated on an annual basis to
monitor heart size and function.
Will a balloon valvuloplasty work in every case?
Rarely, the coronary arteries develop abnormally and encircle
the pulmonary artery causing a narrowing or stricture. This occurs
most often in bulldogs and boxers. If abnormal coronary arteries
are suspected on the echocardiogram, a coronary angiogram is
performed under anesthesia. Balloon valvuloplasty cannot be
performed in dogs with abnormal coronary arteries, significant
annular hypoplasia or supravalvular stenosis. As high as 15-20% of
patients that appear to have favorable anatomy and a technically
successful procedure derive minimal benefit from the procedure.
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