Question and Answer – Heart Failure

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Dear Your Own Vet,

My vet says my dog has heart failure.  What is heart failure and how do I treat my dog for this?

Kat Forsyth


Dear Kat,

I have taken this excerpt from our heart disease health page which should explain everything you need to know


Dr Claire Demmer

BVSc (Hons)



the heart has two sides and 4 chambers
Heart failure occurs when the heart cannot get enough oxygen and nourishment to the tissues of the body

Heart Failure

Heart failure occurs when the heart disease has become bad enough that the heart no longer sends enough blood, and thus enough oxygen and nutrition to the internal organs, and they start to take strain and not function properly. Or, if the fluid pooling in the veins has accumulated in the lungs to the extent that an animal is not able to get enough oxygen in because the lungs, which are normally filled with air, are filled with water. If the fluid pooling in the liver and abdominal cavity accumulates to the point where the liver can’t function well and the animal doesn’t eat this also is classed as severe heart failure.

Signs of Heart Failure

There are 2 sides to every heart and thus 2 types of heart failure – left and right, although sometimes both types are seen

Left Sided Heart Failure

Coughing, especially at night

Gums are pale and tongue has a bluish tinge

Sudden collapse and fainting spells

Poor appetite

Wheezy breathing

Pounding heart

Weak pulse

Drops of moisture round nostrils

Animal won’t settle and sits up and struggles to breathe

Heart murmur

Racing pulse

heart failure, signs of
Pale gums can be seen with heart failure

Right Sided Heart Failure

Bloated belly

Cats that show difficulty in breathing with a heaving chest, sitting up and not settling and bluish tinged tongue

Poor appetite

Pale gums

Heart murmur

Racing pulse

Diagnosis of Heart Failure

Heart failure can be picked up by your veterinarian on the table, using the signs listed above. It is recommended, though, that your vet does further tests to assess how bad the heart failure is and where the problem lies. Chest X rays should be done,  and at least 2 views (one from the side, one from the top or bottom of the animal) should be taken to assess heart size, look for fluid build up in the lungs and check for growths at the base of the heart that could cause heart failure. Echocardiography or ultrasound of the heart is also useful. This will pick up the strength of each contraction of the heart as well as how much leakage is occurring through damaged heart valves. Any inborn or congenital heart defects will also be picked up at the same time, the thickness of the heart muscle will be assessed, the size of each chamber of the heart will be measured and any tumours or masses inside the heart can be seen at the same time.  ECG or electrocardiogram is useful if an arrhythmia is suspected. Your vet should also check for Heartworm, if you live in an area where Heartworm is found, and treat for it.

Treatment of heart failure

Heart failure is treated most commonly in 3 ways:

1. By getting rid of all the extra water on the chest and in the belly.

Diuretics are usually used for this. These drugs make the kidneys lose water, by drawing   more water out of the blood, which makes the blood thicker. This thick blood attracts water by osmosis,  and this draws water out of the lungs and abdominal cavity back into the blood to replace the water lost.  The most common two drugs used to this are Furosemide or “Lasix”  and Spironolactone or “Spiractin”.   These drugs take a few hours to work if given orally. Furosemide can be injected into a vein or under the skin for a more rapid effect. If an animal is really struggling to breathe or is really bloated and distended, fluid may be drawn directly out of the chest or abdominal cavity with a needle to save it’s life.

2. By giving drugs that allow the heart to function more effectively.

ACE inhibitors, such as Enalapril, Benazepril and Captopril,  of which the common trade names include “Renitec”, “Enacard” and “Fortekor”, act by reducing the blood pressure slightly. This slightly lowered blood pressure allows the heart to ease up a little and not work as hard to pump blood out. This saves the sick heart muscle from overworking and extends it’s life. These drugs also have a mild diuretic effect. They stop the kidneys producing an enzyme that would increase blood pressure and cause the body to retain water and thus lower blood pressure and cause mild water loss from the body.

ACE inhibitors used treat heart failure
ACE inhibitors are widely used to treat heart failure

Drugs such as Digoxin have been used to treat heart failure since ancient times. Digoxin, which goes by the trade name “Lanoxin” increases the strength of the contractions of the heart muscle, enabling the heart to push harder with every beat. Digoxin should only be used if there is no obstruction, such as a valve that won’t open and should not be used if there is thickening of the heart muscle, or hypertrophy. For these reasons, it should not be used as the first choice of drug, and then only after a heart scan.

Beta blockers and Calcium channel blockers can also be used to treat some cases of heart failure. Beta blockers slow the heart down, and thus stop it from over working. Calcium channel blockers reduce blood pressure by reducing the force of the heart muscle’s contraction.  Aminophylline or “Millophyline” is sometimes still prescribed to control the coughing that occurs with heart failure as it opens the airways. It does, however, tend to increase the rate of the heart at the same time, as it is a caffeine derivative, so should only be used in certain cases.

3. By modifying the diet

Diets that are low in salt are recommended for heart failure such as the Hills H/D diet. Also if a patient is very fat, he may be put on a reduced calorie diet such as the Eukanuba Restricted Calorie in order to lose weight so that the heart doesn’t take any unnecessary strain.

Presription diet food for dogs
One of the diet foods available to aid weight loss in dogs.

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