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The Heart of the Matter- an article about heart failure
Portia is a very sweet old lady. I have known her for two years. She has a wonderful temperament, a slightly vacant expression, a love of leaning on people and an under active thyroid gland. She is a ten- year- old Doberman and belongs to my boss, Alison Jones. She also has a condition that is quite commonly seen in older dogs and her breed is one that is frequently affected. She has heart failure.
This expression causes great concern to us humans but is a very different disease in dogs and only rarely causes sudden death. Humans that suffer heart attacks often have thickening and narrowing of the arteries in the heart because of our unhealthy life- styles. This leads to sudden loss of blood to the muscle of the heart and a myocardial infarction or heart attack. As dogs tend not to smoke or eat lots of fatty food this is not the case. There are a few different types of heart disease in dogs and they vary between sizes of dogs and breeds so we will concentrate on Portia.
About a month ago she developed a cough and had slowed down considerably in a short space of time, becoming out of breath when she would not normally. Her lungs sounded normal and she had no signs of tracheal irritation as you get with ‘kennel cough’. We knew she was prone to this condition because of her breed and age and the cough is a very classic and typical sign so we decided to x-ray her chest.
We found that her heart had become much larger than it should be. The most likely diagnosis is a condition called dilated cardiomyopathy (DCM). Basically what happens is that the heart muscles starts to lose its ability to contract as well as it should. This means that its output of blood is reduced and blood tends to well up in the heart without really being moved efficiently. This, in turn, dilates the heart and the walls become floppy and thin. A vicious circle develops because the thinner heart walls have less strength to pump blood and so the whole situation gets worse. Also as the heart dilates the valves that should form a nice tight seal when the heart beats become widened and stop forming a good seal so the blood gets pumped even less efficiently.
The physical size of the heart presses on the airways and a cough develops. You also get fluid building up in the lungs called pulmonary oedema because the blood is not being pumped out and this oedema also contributes to the cough. Portia had slowed down, not because of age but because her heart simply couldn’t keep up with the demand for oxygen when she was exercising and she was getting short of breath.
As with many cases of failing organs such as the heart, liver and kidneys, animals will tolerate it for a long time without showing any signs. They are not complainers like we are. Unfortunately this usually means that the disease is quite advanced before we pick it up. Portia’s heart could have been weakening for months or even years before she started coughing.
The outlook isn’t as bleak as you may think. Thanks to modern drugs we can support the heart and life can be prolonged, in some cases for years. Initially, the main symptoms are usually because of the fluid that has built up in the lungs. This is flushed out using drugs called diuretics. These make the kidneys excrete much more urine than usual and the circulation contracts, effectively ‘sucking’ the excess fluid out of the lungs. This brings instant relief and in some cases the dog appears to have a new lease of life because they can suddenly breathe more easily. Long term we use drugs such as ACE inhibitors. These basically act by reducing the work the heart has to do by keeping the amount of fluid in the circulation to a minimum. This means that the heart has to pump a smaller volume round the body. ACE inhibitors originally came from human medicine and many of the drugs we use are identical. It is these inhibitors that ultimately prolong life. On the whole I often find that after a couple of weeks we can reduce the diuretic dose and can sometimes get the dog off them altogether and just rely on the ACE inhibitors or other types of heart drugs to do their work. This way we have the diuretics in reserve for when they are needed. This is invariably the case. You see, the condition is progressive and will continue to deteriorate because the damage has already been done. All we can do is try to slow down the progression of the failure.
I once had an Irish Setter brought in that was practically on ‘death’s door’. He could barely walk and was gasping for air. His tongue was a bluish colour because of lack of oxygen and I really thought at first sight that I would have to put him to sleep. The owner was keen to try and when I left the practice a year later he was still going strong and his quality of life was very good. So you see, if your dog develops heart failure don’t despair straight away. It is well worth trying the drugs as they usually make an enormous difference. As for Portia, she is still a little vacant, still likes leaning on people and now can once again be seen chasing about after the elusive rabbits on the hill with her friends Pan and Badger.