Hello, wonderful puppy parents! Bringing home a new puppy is one of the most joyful experiences. During one of your first vet visits, your veterinarian will listen carefully to your puppy's heart. Sometimes, they can pick up on a "birth defect" of the heart, known as a congenital heart defect. Let's explore what this means.
What is a Congenital Heart Defect?
"Congenital" simply means "present at birth." A congenital heart defect is a structural problem with the heart or the major blood vessels that a puppy is born with. These defects can range from being very mild and never causing a problem, to being severe and life-threatening.
These are different from the "acquired" heart diseases that dogs develop as they get older, like Mitral Valve Disease or DCM.
The Most Common Congenital Heart Defects
There are many types of congenital heart defects, but a few are seen more commonly than others.
1. Patent Ductus Arteriosus (PDA)
This is one of the most common defects, especially in smaller breeds like Maltese, Poodles, and Pomeranians. Before a puppy is born, there is a small blood vessel called the ductus arteriosus that connects the aorta and the pulmonary artery. This vessel is supposed to close within a few hours after birth. If it stays open (or "patent"), it's called a PDA.
A PDA allows blood to be abnormally shunted from the aorta back into the pulmonary artery, which puts a huge volume overload on the left side of the heart. This creates a very classic, loud, "machinery-like" continuous murmur.
The great news: A PDA can often be completely cured with a minimally invasive procedure!
2. Subaortic Stenosis (SAS)
SAS is a narrowing of the area just below the aortic valve, which is the valve that blood flows through to get from the heart to the rest of the body. This narrowing forces the heart to pump much harder to get blood out, which can cause the heart muscle to become very thick.
This is a serious defect that is inherited in large-breed dogs like Golden Retrievers, Rottweilers, and Newfoundlands. It can lead to fainting, arrhythmias, and even sudden death.
3. Pulmonic Stenosis (PS)
This is very similar to SAS, but it's a narrowing of the pulmonic valve, which is on the right side of the heart. This valve lets blood flow from the heart to the lungs. PS is common in brachycephalic (flat-faced) breeds like English Bulldogs, French Bulldogs, and Boxers.
More good news: Moderate to severe PS can often be treated with a minimally invasive procedure.
4. Ventricular Septal Defect (VSD)
A VSD is a hole in the wall (the septum) between the left and right ventricles (the bottom chambers of the heart). This allows blood to shunt from the high-pressure left side to the low-pressure right side. A small VSD may cause no problems, but a large VSD can lead to heart failure.
Spotting the Signs
- •A Heart Murmur in a Puppy: This is the #1 sign. While some puppies have innocent murmurs they grow out of, a loud murmur is a big red flag.
- •Failure to Thrive: A puppy with a significant heart defect may not grow as well as their littermates.
- •Exercise Intolerance: They may get tired very easily when playing.
- •Coughing or Difficulty Breathing: These are signs of congestive heart failure.
- •Fainting (Syncope): This is a very serious sign.
Diagnosis: Finding the Problem
If your vet hears a suspicious murmur in a puppy, they will recommend a workup with a veterinary cardiologist.
- •Chest X-rays: Can show if the heart is enlarged.
- •Echocardiogram (Heart Ultrasound): This is the key test! An echo will allow the cardiologist to identify the exact structural defect, see how blood is flowing, and determine the severity of the problem.
Treatment: Fixing the Heart
The treatment depends on the specific defect.
- •For a PDA: The treatment of choice is a minimally invasive procedure where a cardiologist guides a special plug (an Amplatz Canine Duct Occluder) through a vessel in the leg up to the heart to block the abnormal vessel. This is curative!
- •For Pulmonic Stenosis: A procedure called a balloon valvuloplasty can be performed. A balloon is guided to the narrowed valve and inflated, which stretches the valve open.
- •For Subaortic Stenosis: Unfortunately, there is no great fix for SAS. The treatment is usually medical management with beta-blockers to try to protect the heart. Open-heart surgery is not commonly performed in dogs.
- •For VSDs: Small VSDs may need no treatment. Large ones are managed with medication for heart failure.
Discovering that your new puppy has a heart defect can be devastating, but it's important to get a clear diagnosis. For many of these conditions, especially a PDA, modern veterinary medicine offers a complete cure, allowing your puppy to live a long, normal, and happy life.
Sources & Further Reading:
- •VCA Animal Hospitals - Congenital Heart Disease in Dogs
- 1Merck Veterinary Manual - Congenital and Inherited Anomalies of the Cardiovascular System in Dogs