The heart is a formidable muscle that never rests and plays in the organism a role of "central pump".
Oxygen-poor blood arrives in the right part of the heart, to be pumped to the lungs, where it is replenished with oxygen. From there it flows back to the left part of the heart this time, which sends this oxygen-rich blood into the various organs and tissues of the body.
The heart valves, which function as valves, ensure that the blood flows in the right direction. In the aging dog, these valves are often altered by tissue proliferations and do not close well. So they let some of the blood flow in the wrong direction.
When the defect is localized in the left part of the heart (the most frequent case), some of the blood flows back into the lungs, where it stagnates, causing coughing, difficulty breathing and a marked decrease in fitness .
When the valves of the right heart are affected, the blood accumulates in the organs of the abdominal cavity (spleen, liver, kidneys, intestines ...), which can ultimately lead to the appearance of abdominal effusions.
In both cases, there is talk of heart failure. By auscultating the heart, one can hear a heart murmur (due to the reflux of blood) more or less strong according to the severity of the valvular alterations.
Affected dogs show initially a cough appearing rather at night or when they are irritated. They get tired faster and changes in time can accentuate the symptoms.
At a later stage of the disease, patients have severe respiratory difficulties and a strong cough. They become apathetic, lose weight and may have fluid in the abdomen, sometimes in the rib cage.
A deficient heart can not be cured. Even so, most dogs can live good lives for months or even years, adapting their living conditions and regularly taking appropriate medications.
The patients concerned are regularly checked clinically (3 - 4 times a year). Auscultation, control of the pulse and mucous membranes, as well as an evaluation of the respiration and the diameter of the abdomen are essential. Depending on the case, X-rays, electrocardiogram, ultrasound or blood and urine tests may be necessary.
Treatment of heart failure
In the case of a deficiency of the heart valves, part of the blood flows backwards, which leads to a decrease in blood pressure in the vascular system. The organism tries to compensate for this decrease by reducing the diameter of its arteries, thanks to small muscles, located in the wall of the vessels, which contract. The pressure will then rise, but also cause an increase in blood flow to the valves, and thus an additional overload for the heart that will make the situation worse. It is a veritable vicious circle.
New heart medicines (called blood depressants) act against this fatal regulation. They cause dilation of the arteries, allowing the blood to circulate better and decreasing the cardiac overload. The resulting drop in tension does not pose any particular problems.
It is advisable to begin treatment with depressants early enough. It will thus set up "smoothly" and will avoid the appearance of irreparable damage.
In case of accumulation of fluid in the lungs, abdomen or thorax, it is recommended to use diuretics in parallel. Other medications can increase the strength of the heart muscle when it shows signs of weakness.
It is important that the patient receives a low-salt diet (bacon, ham, sausages, peanuts, chips are contraindicated for example). There are special foods for dogs with heart disease that can be obtained from the veterinarian.