Mitral Valve Disease
Heart mitral valve disease (MVD) is the leading cause of death of cavalier King Charles spaniels throughout the world. MVD is a polygenetic disease which statistics have shown may afflict over half of all cavaliers by age 5 years and nearly all cavaliers by age 10 years, should they survive that long. MVD has been found to be 20 times more prevalent in CKCSs than in the average dog breed. It is estimated to affect 10% of the entire dog population, but at a much older age of onset than for CKCSs.
MVD is a degeneration of the heart's mitral valve, one of four sets of valves in a dog's heart. A dog's heart valves' leaflets must open and close tens of thousands of times a day to maintain uni-directional blood flow through the heart. When the valves open, they direct blood flow forward to where it is supposed to go, and when they close, they prevent blood from going backward to where it is not supposed to go. The mitral valve is located between the left atrium and ventricle.
As the mitral valve degenerates, the valve no longer fully closes after each pumping action, allowing some blood to flow backwards through them from the ventricle back into the atrium. As the condition worsens, more and more blood is able to backflow through the valve as the leaflets of the valve begin to flail. In the final stages, the valve’s struts (chordae tendineae) sometimes break, causing the valve to collapse completely. In most dogs affected with MVD, the disease seldom progresses to heart failure. The estimates have varied from 20% to 30% of all dogs diagnosed with MVD eventually going into heart failure. However, MVD usually results in heart failure in the CKCS.
Heart failure (HF) or congestive heart failure (CHF) is a condition where the heart is still working, but it can't pump enough blood to fully meet the dog's body's needs. HF is determined by its symptoms, which include high rates of breathing (respiratory rates), exercise intolerance, shortness of breath (dyspnea), increase in respiratory effort, and/or fainting. The term "congestive" refers to the heart's dysfunction causing increased blood pressure in the veins and capillaries, leading to fluid buildups in the heart and eventually in the lungs (edema) or elsewhere (effusions).
About 10% of all dogs suffer from some form of heart disease. Mitral valve disease is the most common heart disorder in older dogs of all breeds. However, in the Cavalier King Charles spaniel, the prevalence of MVD is about 20 times that of other breeds. Also in cavaliers, the onset of the disease typically is much earlier in the life of the dog. It has been reported that, once diagnosed, mitral valve disease is much more rapid in cavaliers than in other breeds, possibly reaching a life-threatening stage within as little as 1 to 3 years, rather than the average 3 to 5 years. To a lesser extent, cavaliers also suffer from deterioration of their tricuspid valves.
All cavaliers should be screened for the sounds of tubulent blood flow, called heart murmurs, once a year beginning at age 1 year. Once MVD is detected, its progression can be monitored with stethoscopic examinations (auscultations), x-rays, echocardiograms, and colour Doppler echocardiograms. If a heart murmur is detected, it should be confirmed in 3 to 6 months. If it still is detected, the dog is considered probable for MVD.
The progression of mitral valve disease can be rapid or slow. In most cavaliers, the disease shows a gradual progression in the loudness of the murmur and to more serious symptoms, in as little as 2 years after first detecting the murmur. Drugs may help to minimise the symptoms, but eventually the drugs may be unable to control them. The drugs prescribed for cavaliers with MVD can sometimes have severe adverse side effects, and blood chemistry should be done routinely to monitor their effects upon the kidneys, liver, and other internal organs. Severe symptoms of MVD in some cavaliers will appear more quickly, although previously having been stable. The ultimate consequence of the disease is heart failure.
MVD is a degeneration of the heart's mitral valve, one of four sets of valves in a dog's heart. A dog's heart valves' leaflets must open and close tens of thousands of times a day to maintain uni-directional blood flow through the heart. When the valves open, they direct blood flow forward to where it is supposed to go, and when they close, they prevent blood from going backward to where it is not supposed to go. The mitral valve is located between the left atrium and ventricle.
As the mitral valve degenerates, the valve no longer fully closes after each pumping action, allowing some blood to flow backwards through them from the ventricle back into the atrium. As the condition worsens, more and more blood is able to backflow through the valve as the leaflets of the valve begin to flail. In the final stages, the valve’s struts (chordae tendineae) sometimes break, causing the valve to collapse completely. In most dogs affected with MVD, the disease seldom progresses to heart failure. The estimates have varied from 20% to 30% of all dogs diagnosed with MVD eventually going into heart failure. However, MVD usually results in heart failure in the CKCS.
Heart failure (HF) or congestive heart failure (CHF) is a condition where the heart is still working, but it can't pump enough blood to fully meet the dog's body's needs. HF is determined by its symptoms, which include high rates of breathing (respiratory rates), exercise intolerance, shortness of breath (dyspnea), increase in respiratory effort, and/or fainting. The term "congestive" refers to the heart's dysfunction causing increased blood pressure in the veins and capillaries, leading to fluid buildups in the heart and eventually in the lungs (edema) or elsewhere (effusions).
About 10% of all dogs suffer from some form of heart disease. Mitral valve disease is the most common heart disorder in older dogs of all breeds. However, in the Cavalier King Charles spaniel, the prevalence of MVD is about 20 times that of other breeds. Also in cavaliers, the onset of the disease typically is much earlier in the life of the dog. It has been reported that, once diagnosed, mitral valve disease is much more rapid in cavaliers than in other breeds, possibly reaching a life-threatening stage within as little as 1 to 3 years, rather than the average 3 to 5 years. To a lesser extent, cavaliers also suffer from deterioration of their tricuspid valves.
All cavaliers should be screened for the sounds of tubulent blood flow, called heart murmurs, once a year beginning at age 1 year. Once MVD is detected, its progression can be monitored with stethoscopic examinations (auscultations), x-rays, echocardiograms, and colour Doppler echocardiograms. If a heart murmur is detected, it should be confirmed in 3 to 6 months. If it still is detected, the dog is considered probable for MVD.
The progression of mitral valve disease can be rapid or slow. In most cavaliers, the disease shows a gradual progression in the loudness of the murmur and to more serious symptoms, in as little as 2 years after first detecting the murmur. Drugs may help to minimise the symptoms, but eventually the drugs may be unable to control them. The drugs prescribed for cavaliers with MVD can sometimes have severe adverse side effects, and blood chemistry should be done routinely to monitor their effects upon the kidneys, liver, and other internal organs. Severe symptoms of MVD in some cavaliers will appear more quickly, although previously having been stable. The ultimate consequence of the disease is heart failure.