Listen to your heart
Each month, we explain a few questions from the Golden Retriever Lifetime Study questionnaire.
The veterinary baseline survey’s questions numbered 8, 23 and 38 all relate to the heart. With February being American Heart month, it certainly is timely to discuss these three questions.
As part of the Golden Retriever Lifetime Study, we ask veterinarians to provide data on their assessment of the heart during study participants’ physical examination, and to provide information on any heart disease they diagnose.
Although advanced testing methods are required to definitively diagnose most heart disease, a veterinarian can learn a lot about a dog’s heart by careful listening. Study veterinarians are asked to pay close attention to heart sounds and heart rhythm.
The heart has four valves that open and close as it receives blood and then pumps it to either the lungs or general circulation. The opening and closing of the valves makes the classic lub-dub sound heard when we listen to the heart. Turbulent blood flow causes a sound known as a heart murmur. We tend to think of heart disease as causing heart murmurs, but murmurs also can be caused by changes outside the heart, such as alterations in blood viscosity (such as anemia), growth (murmurs in puppies that disappear in adulthood), and when the heart is under extra stress (pregnancy). The heart also can make whistling, clicking and snapping sounds that sometimes are associated with disease. Our study veterinarians are asked to carefully categorize any sounds they hear during physical exams. At baseline, 68 study dogs had murmurs detected.
Heart rhythm refers to the regularity or irregularity of the heart sounds, as well as the heart rate. In general, veterinarians consider heart rate normal if there is a steady, regular beat. The most common irregular beat noted in dogs is called a sinus arrhythmia, which means the heart rate speeds up during inhalation and slows during exhalation. Sinus arrhythmias are not considered unusual, but other irregular beats warrant further investigation.
The questionnaire also asks the veterinarian to document whether the study participant was newly diagnosed with any primary heart disease. These include cardiomyopathy, which are diseases of the heart muscle, as well as any type of heart valve problem. Common heart valve problems include valves that don’t close fully, resulting in back flow of blood through the leaking valve; as well as inherited problems such as subaortic stenosis. Subaortic stenosis is caused by a band of fibrous tissue just below the aortic valve, obstructing blood flow out of the heart, and is one of the most commonly inherited heart problems in golden retrievers. At baseline, 23 study dogs were diagnosed with this condition. The study design allows us to follow these dogs throughout their life, providing a unique opportunity to study the evolution of a variety of heart diseases over time.
Finally, veterinarians are asked about heartworm status, and to list any other cardiovascular conditions. The heartworm data can be compared to geographic data as well as information on preventive strategies reported in other areas of the questionnaire.
Morris Animal Foundation and the Golden Retriever Lifetime Study team thank the participants, veterinarians, volunteers and supporters who are working hard to make this study successful.