Information For Clients

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 heart failure.

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 death.

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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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 initial diagnosis.

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.

Surgical Ligation:
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 hospital care.

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 be performed?

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 surgery?

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 puppies.

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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 stenosis.

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.

Balloon valvuloplasty:
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.

Surgery:
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 occlusion.

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 medication.

Should a dog with a pulmonic stenosis be used for breeding purposes?

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 valvuloplasty?

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 valvuloplasty?

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 valvuloplasty?

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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