Written by Danielle Steenkamp, DVM
Silken Windhounds are generally considered by most fanciers to be a healthy breed, especially regarding cardiac health. There have been scattered reports of sudden death, mitral valve disease, and congenital abnormalities reported. Two of the foundation breeds, borzoi and whippets, both consider cardiac monitoring in their breeds as an important aspect of pre-breeding screening. Gathering data and screening is critical in a rare breed and gathering that data before a problem is obvious can lead to better outcomes for the health of the breed as a whole. Collecting and saving this data for researchers will be monumental in moving forward if a problem is found.
A holter monitor is a device that can be purchased, shared, and used at home. The expense is much less than that of an echocardiogram and it may be more accessible for people looking to initiate some type of cardiac screening in their breeding program outside of auscultation.
Auscultation vs. Echocardiogram vs. Electrocardiogram vs. Holter
Auscultation of the heart is when we listen to it with a stethoscope. Auscultation is most commonly used to detect heart murmurs, but the cause of the murmur cannot be determined through auscultation alone. Occasionally, in more significant disease, one can auscultate an arrhythmia, but again, the type of arrhythmia is not able to be determined through listening. Unfortunately, not all types of cardiac disease present with a murmur and not all murmurs are abnormal – in fact, in athletic dogs such as whippets and borzoi, many murmurs are not associated with disease. This makes auscultation alone an insensitive screening tool when screening for heart disease.
An echocardiogram (echo) is an ultrasound of the heart. They are used to look for structural changes to the heart muscle and valves and evaluate the pumping ability of the heart. Echocardiograms are one of the most widely used diagnostic imaging tools in cardiology. Echocardiograms can be difficult to obtain due to a shortage of veterinarians able to perform them and they can also be cost prohibitive. If a murmur is heard on auscultation, and echocardiogram is always advised.
An ECG or electrocardiogram is usually a 3–5-minute test where a dog is hooked up to a series of leads and the electrical activity of the heart is recorded. While an echo looks at the structure and pumping ability of the heart, an ECG looks at the electrical activity that forms a heartbeat and can tell us whether the heartbeat is normal or if there is an arrhythmia present.
Echocardiograms usually record an ECG during the procedure. Unfortunately, arrhythmias are often not static except in cases of advanced disease. This means they may be there and severe one minute and then disappear for a week. This doesn’t mean that the arrhythmia isn’t dangerous, it just means it can be hard to catch on a 5-minute reading.
A Holter monitor is a small device that recoreds a 24–48-hour ECG. Theoretically, the longer the monitoring time the more likely we are to “catch” the arrhythmia. In human medicine, holters are now often worn for 1-2 weeks. That isn’t feasible in dogs at this time, so we settle for 24-hour readings (unless there is a suspected arrhythmia and 48 hours is indicated).