I received an email from a concerned pet owner about their young puppy having what the vet called an “innocent” heart murmur, asking if I thought the puppy would be able to handle training classes. Hearing that your puppy has an irregular heartbeat can be scary. However, in most cases, they do tend to resolve, and your puppy will be just fine. Let’s talk about when I would worry about the presence of a heart murmur.
A heart murmur can be defined as an abnormal heartbeat. Murmurs are graded on a scale of one to four. Grade one is the least significant, and four is the most. They are either systolic, which happens when the heart is contracting, or diastolic, meaning they occur when the heart is relaxing.
According to the American Kennel Club, approximately 28 percent of all puppies under six months of age have what is called an “innocent” or “physiologic” heart murmur upon their first exam. This number can jump to 58 percent in sporting breeds. When a puppy under four to six months of age is examined, the murmur could be a result of excitement and increased blood flow. A murmur in puppies under six months old could also be due to stages of heart development or changes taking place in the flow of blood through the heart. Innocent heart murmurs tend to resolve themselves no later than six months of age.
When would I become concerned?
Over the course of breeding Bull Terriers for 20 years, I have had one puppy that may have had an innocent murmur. Sometimes, the three different vets I took him to heard it; sometimes, they did not. On the days it was not heard, it was when he was standing completely still and not jumping around or becoming excited. When the puppy was around six months old, I took him for an echocardiogram to rule out any structural issues or congenital birth defects in his heart, because I did have plans to use him in my breeding program. If this dog was not intended for breeding, I would not have rushed to get the EKG unless his heart murmur was getting worse and there were other symptoms such as shortness of breath, stunted growth, or being unable to hold his weight. Some breeds that are deep-chested, like Dobermans, Boxers, and Bull Terriers, will also have a different rate of blood flow through the heart because of their physical structure. So, I merely wanted to ensure that this dog’s heart was developing normally. I repeated the EKG when he was three years old, and his heart was completely normal.
When I would worry about a heart murmur in any dog, regardless of age, is when it is consistently heard during exams, is graded either a three or a four, and there are other physical symptoms that are seen daily. Congenital heart defects will most likely be accompanied by a higher grade of murmur. The puppy also would have other symptoms, such as shortness of breath, lethargy, poor appetite, and stunted growth.
While it may be scary to hear that your puppy has a heart murmur, try not to panic right away! I know more puppies that have had innocent heart murmurs at a young age than I do that have had congenital birth defects. The best course of action is to listen to your vet. Ask about the grading of the murmur and have the heart rechecked at intervals to see if it is heard each exam. At each exam, note if it is getting worse or remains the same. If the murmur is still present beyond six months, there is never any harm in seeking a second opinion from a cardiologist to put your mind at ease. Worst-case scenario, it could uncover any defects early on that can be treated.
If you have any questions, please feel free to email me at heidi@fouronthefloordogtraining.net.
Heidi Clayton started Four On the Floor Dog Training to provide positive, reward-based dog training in South Jersey. She breeds, trains and shows bull terriers under the SoraBully’s Bull Terriers kennel name. Email questions to heidi@fouronthefloordogtraining.net or learn more at https://fouronthefloordogtraining.net
