It is estimated that around 50% of cavaliers will have MVD by the time they are 5, and 90% by the time they are 10. Reputable breeders are working hard to minimize the odds of this in their bloodlines, but it is not an exact science. MVD is a complex disease.
Unfortunately we can not genetically test for it, so we have no way to predict which puppies may or may not get it. We do know it is polygenic. This means that it must be inherited from both sides, and it does seem to look like it can be passed hidden through many generations before popping up in the “perfect storm” in one puppy who exhibits the symptoms.
There also seems to be 2 types of MVD – one is slow progressing – dogs will get a murmur (sometimes young) and can live till old age. The other is more heartbreaking as it is fast progressing and the heart valves deteriorate quickly and it seems that these dogs die only a few years (or maybe a year) after diagnosis.
The heart is divided into four chambers. The lower chambers are called the ventricles and the upper chambers are the atria or if discussing just one it is called the atrium. There are valves in-between the chambers that open and close, thus keeping the blood flowing in one direction. The Mitral Valve is located between the left atrium and the left ventricle.
Thus the Mitral Valve is considered one of the most important parts to keep the heart functioning correctly and preventing blood from flowing backwards. If the mitral valve does not close properly, blood can flow back into the atrium preventing continuous blood flow. The heart has to work harder to keep the blood flowing causing the walls of the heart to thicken and eventually leads to congestive heart failure.
All Cavaliers need to be annually examined with a stethoscope. This is known as an auscultation exam. Some regular veterinarians can hear imperfections, clicks, heart murmurs and arrhythmias but not all of them, and they certainly cant diagnose what they mean as well as a cardiologist, so I would recommend going to a cardiologist once a year – or two at the most. The cheapest places to do this would be at local Club health clinics. Many local cavalier clubs will host health clinics 1-2 times a year. Here in Seattle we have the Cavaliers of Puget Sound but a quick google search of “cavalier” and your state will bring up your local clubs. Usually they charge a nice “bulk discount” like $35 for hearts and $25 for eyes or something like that.
If the cardiologist hears a suspicious sound, they will do an echocardiogram with an ultrasound machine. Echocardiograms will give a visual display of the heart, blood flow and activity. Blood flow can be seen as blue or red depending on the direction on the new Ultrasound machines and gives a clear visual picture if there is Mitral Valve irregularities. Breeders who are especially health conscious will also perform echocardiograms on their dogs every couple of years as dogs can develop MVD without any murmur being present.
There are not many symptoms that a cavalier has mild MVD issues. It is not until it has fully progressed that you will notice shortness of breath, reduced activity, coughing or additional naps. That is why annual exams are most important.
The progression of MVD can be slow or rapid. It is generally accepted that early onset seems to progress faster than the later onset. There is no cure of MVD however, there are some excellent cost effective medications that are available. Most Cavaliers live a normal life if MVD is found early and the progression is slowed. Medications should be given as prescribed and a special diet may be suggested.
With the potential risk of MVD, it is highly recommended to keep all adult Cavaliers at a healthy weight and well exercised. Supplements of CoQ10, Fish Oils with Omega 3 and Antioxidants such as Ventri-Science Cardio Canine are all excellent.