PDA: Is My New Puppy Tired Because of a Heart Problem?

Dr. Phil Zeltzman is a traveling, board-certified surgeon in Allentown, PA. His website is www.DrPhilZeltzman.com. He is the co-author of “Walk a Hound, Lose a Pound” (www.amazon.com).

Freddy was a very cute 10-month-old Collie. He was cute, but he looked and acted very different from his littermates. He was reluctant to play and seemed to tire quickly—unlike his siblings who had unlimited amounts of energy. Freddy was a finicky eater with a stunted growth, which means that he was underdeveloped, compared to his littermates.

Freddy's guardian took him to his family veterinarian to try and figure out why he behaved that way. Everything seemed to check out normally during the physical exam, except for a loud heart murmur. An ultrasound of the heart, called an echocardiogram, was recommended. The ultrasound diagnosis was very clear: Freddy had a PDA.

What is PDA in a puppy?
PDA (which stands for Patent Ductus Arteriosus) is an abnormal vessel that connects two large arteries, right next to the heart: the pulmonary artery and the aorta. A PDA is a congenital abnormality, which means that affected dogs, and less commonly cats, are born with it. Some of the blood is directed away from the lungs and is not well oxygenated, causing weakness and low energy.

What causes PDA in a puppy?
This vessel is normal in the fetus and should shut down at birth. Since Mother Nature did not shut Freddy’s PDA off, human intervention was necessary. Without surgery, he would end up with heart failure. The surgery entails a thoracotomy, which means opening up the chest cavity. Doing this in less traumatic than it sounds. We go between two ribs, so there is no need to cut bones.

How is PDA treated in a puppy?
The next steps to treat a PDA are:

  • Confirm the PDA
  • Free it up and delicately place two stitches around it
  • These special sutures are tied to shut off the PDA and redirect the blood where it should go

This surgery can be quite risky and stressful for the surgeon. Whereas the two big arteries (the pulmonary artery and the aorta) are tough-vessel-blood-vessels, the PDA is a very fragile structure. The main risk of the surgery is in tearing the PDA, which can cause massive bleeding and possibly death of the patient. PDA surgery for a puppy
We opened Freddy’s chest up. We could see his lungs and his beating heart. I could feel a mixture of awe and tension in the OR. We were able to isolate the PDA. It was very large, and we could feel the characteristic irregular blood flow, called a “thrill,” inside the vessel. We placed the two special sutures around it. As the first suture was tied off, the intensity of the PDA decreased and suddenly stopped. We tied the second suture and I whispered: “it worked.” Everybody in the OR breathed a sigh of relief.

We closed the chest and placed what is called a chest tube to remove air from the chest cavity. Freddy recovered uneventfully from anesthesia. The next day, the chest tube was removed and Freddy went home. Although open chest surgery is clearly invasive, we now have enough pain medications available to make patients like Freddy very comfortable.

Recovering from a PDA
Freddy went home on pain medications and antibiotics, with instructions to keep him very quiet for four weeks. He also had to wear a plastic cone (Elizabethan collar) to prevent him from licking or chewing at the skin staples.

Four months after surgery, I called Freddy's guardian to see how things were going. She reported that he was great and had a good appetite. He was essentially back to normal. Surgery was a complete success.

To be fair, there is a less invasive way to treat PDA. It typically requires finding a knowledgeable cardiologist who has access to advanced technology and knowledge. When this is not possible, then open chest surgery is a perfectly acceptable solution.

I've always had a personal fondness for PDA surgery. They always occur in puppies and typically involve loving and motivated guardians. It's a wonderful feeling to literally feel a life-threatening abnormality under your fingers, and instantly make it vanish.

Question to ask your veterinarian

  • Why is my puppy behaving differently from his sibling?
  • Why is my puppy’s appetite decreased?
  • If a PDA has been diagnosed, who is the best person to fix it?

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.

Reviewed on:

Wednesday, March 11, 2015


As you can see, sick dog symptoms can give us an idea as to what the problem is, and how sick our dog is, so we know what we need to do.

In trying to decide what to do, one of the major considerations is age.

Older dogs have weaker immunity and less reserve, and if an older dog suddenly shows some of the above sick dog symptoms, it is more of an urgent problem than a younger dog because things can deteriorate much faster in an older dog.

Another factor that determines what action to take is, how quickly and how severely our dog has become ill.

If the sickness symptoms come on very quickly (within a few hours or a single day), then obviously this is more urgent and serious than if the symptoms develop over weeks or months.

PDA: Is My New Puppy Tired Because of a Heart Problem? - pets

This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian.

Enalapril (Enacard, Vasotec), Benazepril (Lotensin), Lisinopril (Prinivil, Zestril).

These drugs are angiotensin converting enzyme (ACE) inhibitors. ACE inhibitors dilate blood vessels and moderate excess hormone activity that occurs with heart failure, resulting in less resistance in the blood vessels against which the heart must pump. These drugs have improved clinical signs of heart failure and prolonged survival in several studies. An ACE inhibitor may be the only drug needed early in the disease process.

The specific drug used and the individual pet’s disease influence the dose and frequency of administration recommended. Enalapril, Benazepril, and Lisinopril can be given either on an empty stomach or with food.

Adverse effects of ACE inhibitors could include vomiting or diarrhea, deterioration of kidney function, elevation of blood potassium levels, or low blood pressure (hypotension). Other adverse effects that have been reported in people taking the drug include skin rash or itchiness, taste impairment, and certain abnormalities in blood and urine tests.

Furosemide (Lasix, Disal, others)

Furosemide is the diuretic ("water pill") most often used to promote the loss of excess fluid in patients with congestive heart failure. The dosage varies depending on the clinical situation and the patient’s response, but generally the lowest dose that controls signs of congestion is used for chronic therapy. Signs of heart failure decompensation and congestion such as a persistent increase in resting respiratory rate or recurrence of cough may respond to an (often temporary) increase in furosemide dose. In most cases (check with your veterinarian first), if your pet has been doing well on heart failure medication but subsequently develops signs of congestion again, you can increase the dose or add an extra dose of furosemide for a day or so. If this becomes necessary, be sure to discuss each event with your veterinarian – reevaluation additional tests, and/or other therapy adjustments may be necessary.

Adverse effects of furosemide are usually related to excessive fluid and/or electrolyte losses (especially potassium) resulting in dehydration and weakness.

Digoxin (Lanoxin, Cardoxin, Cardoxin LS)

Digoxin is a positive inotropic (refers to the ability to contract) agent that mildly strengthens heart muscle contraction. It also moderates the excess neurohormonal activity that occurs with heart failure and helps control certain heart rhythm abnormalities. Digoxin is not necessarily indicated in every case of heart failure.

Digoxin is best given on an empty stomach since food as well as antacids and kaolin-pectin compounds decrease drug absorption.

The toxic effects of digoxin can be serious and even life threatening so the drug must be carefully dosed. Monitoring of the drug concentration in the blood is recommended. This is often done 7 to 10 days after starting the drug or after making a dosage change. The blood sample is taken 8 to 10 hours after a dose of the drug has been given. Reduced kidney function, dehydration, loss of lean muscle mass, low blood potassium levels, and certain drugs increase the potential for digoxin toxicity.

Adverse/toxic effects can include heart rhythm disturbances, loss of appetite, vomiting, diarrhea, and depression. If you suspect digoxin toxicity, stop giving the digoxin and contact your veterinarian immediately.

Diltiazem (Cardizem, Cardizem CD, Dilacor XR)

Diltiazem is a calcium channel blocker that is used to help control certain heart rhythm disturbances and to promote heart muscle relaxation in hypertrophic cardiomyopathy (especially in cats). In dogs with atrial fibrillation (a rapid, irregular, abnormal heart rhythm) it may be used with digoxin to slow the rate of the heartbeat.

Adverse effects are uncommon at standard doses but can include decreased appetite, slow heart rate, and rarely, other stomach/intestinal or heart effects.

Atenolol (Tenormin) and Propranolol (Inderal)

These drugs, among others, are called beta-blockers. They antagonize the effects of the sympathetic nervous system, and thereby slow the heart rate, reduce the heart’s oxygen demand, and help control certain heart rhythm disturbances. A beta-blocker may be used with digoxin to slow the heartbeat in dogs with atrial fibrillation. A beta-blocker may be useful in cats with hypertrophic cardiomyopathy as well as animals with certain congenital heart malformations.

Adverse effects are usually related to excessive beta blockade and individual animals vary considerably in their response thus, low doses are used initially and slowly increased to effect. Dosage and frequency of administration also depends on the drug used. Adverse effects can include excessively slow heart rate, worsening of heart failure, low blood pressure, bronchospasm (more likely with Propranolol), depressed attitude, and possibly masking early signs of low blood sugar (especially in diabetics).

Nitroglycerin (NitroBid, Nitrol) and Isosorbide dinitrate (Isordil, Sorbitrate)

These drugs are prescribed sometimes to dilate veins and help reduce congestion. Nitroglycerin ointment is applied to the animal’s skin, often in the groin or armpit area or inside the earflap.

Gloves or an application paper should be used to apply this medicine to your pet. Do not get this medicine on your skin because you will absorb it also.

Isosorbide comes in pill form.

Spironolactone (Aldactone)

Spironolactone is another diuretic that works by a different mechanism from furosemide. It is sometimes used in addition to furosemide in the treatment of chronic, refractory congestive heart failure. Adverse effects relate to excess potassium retention and stomach/intestinal upset. If used with an ACE inhibitor or oral potassium supplement, blood potassium must be monitored closely.

Chlorthiazide (Diuril) or Hydrochlorothiazide (Hydrodiuril)

These drugs are diuretics that are sometimes used with furosemide for refractory heart failure. Adverse effects are usually related to excessive fluid and/or electrolyte losses.

This Pet Health Topic was written by O. L. Nelson, DVM, MS, Diplomate ACVIM (Cardiology & Internal Medicine) Washington State University.

Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.

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Struggling to cope

‘After about a week, I just felt like a complete failure. I was so tired I couldn’t think straight and everything seemed to be going wrong. Monty was still peeing and pooing in the house, he’d chew anything that he could find, and any time I turned my back, he’d be doing something he shouldn’t. This was causing conflict in the family and I couldn’t even leave him to go to the shops to get away from it all. I hadn’t realised that having a puppy was so difficult and twenty times a day I nearly picked up the phone to his breeder to ask her to take him back because I couldn’t cope. I’m so glad I didn’t though as he’s now my best friend and I couldn’t ever imagine life without him.’

- Lindsey, owner of Monty, now a 14-month-old Golden Retriever.

Your dog may have been born with a heart defect. Old age, injury and infection can exacerbate it. Diet and exercise play roles too.

Take notice of these early symptoms of heart problems:

  • Coughing more than usual (during or after exercise or a few hours before bedtime)
  • Having a hard time breathing or exercising
  • Tiring easily
  • Pacing before bedtime and having a hard time settling down
  • Increased respiratory rate -- how many breaths per minute

More symptoms may develop, as the disease gets worse, including:

  • A swollen belly from fluid buildup in (called ascites)
  • Fainting because of blocked blood flow to the brain
  • Change in tongue or gum color to bluish gray because of poor oxygen flow
  • Weight loss as your dog loses their ability to store healthy fat

Watch the video: Your First Day And Night With A New Puppy - Bringing Home A New Puppy Episode 2

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