Heart disease is a serious problem that affects a large number of dogs.
The heart is a muscular organ consisting of four chambers, two of which are located on the left side of the heart, and two on the right side. Each side of the heart also has a set of valves. When heart disease is present, certain parts of the heart cease to function properly.
Heart problems in dogs can be very serious and life threatening and often present without our awareness or prior warning. They can vary from congenital or hereditary problems that they are born with, to problems of old age such as congestive heart failure in dogs or secondary to other conditions such as hyperthyroidism (overactive thyroid).
There are two common heart conditions –
- Valvular Insufficiency and Congestive Heart Failure
This page will discuss Valvular Insufficiency.
Valvular Insufficiency and Congestive Heart Failure
What is a valvular insufficiency?
Valvular insufficiency occurs when damaged and thickened heart valves develop. This is more often found in small and medium size dogs. Valve problems are unusual in larger-breed dogs but they may develop.
In the small breeds of dogs, valvular insufficiency begins in midlife and progresses slowly. The disease is associated with thickening and shortening of the valve components that separate the upper (atria) from the lower (ventricles) parts of the heart.
Remember, normally blood flows in only one direction. If the valves fail to close completely when the heart contracts, blood moves forward but some leaks backward.
What are the clinical signs?
Clinical signs vary depending on whether the right and/or left side of the heart is affected and whether heart enlargement presses on the windpipe. Fluid accumulates when the heart fails to pump enough blood to the body and instead the blood is transmitted backward from the heart to the lung or body.
Owners of pets with valve problems see;
- Inappropriate panting
- Heavy breathing
- Diminished exercise ability
- Occasional Fainting
The cough usually starts at night and progresses to daytime as well, particularly when associated with exercise. Retching and non-productive gagging follow the cough. When the left side of heart is affected, fluid may accumulate around the lungs, making it difficult to breathe. If the right side is affected, fluid accumulates in the abdomen, making it swell.
What tests are needed?
- Physical examination
Abnormal heart sounds can be heard with a stethoscope
- Electrocardiogram (ECG)
An electrocardiogram (ECG) to identify heart enlargement or irregularities of the heart’s rhythm.
- Radiographs (x-rays)
X-rays can demonstrate heart enlargement and/or inappropriate fluid accumulation.
- Blood Test
Blood testing can identify hormonal, kidney, or other internal medical problem.
An ultrasound examination (echocardiography) accurately pictures enlarged heart chambers, abnormalities of valve structure, and the heart’s pumping ability.
What is the treatment?
A number of treatments are used for pets with valvular heart disease. They include;
- Exercise restriction. Walking is a good exercise.
- Pimobendin. A medication used to strengthen the heart and to treat some irregularities of its rhythm. It maintains a slower and more effective heart muscle contraction.
- Diuretic agents. Commonly given to remove excess water accumulation from the body and can cause increased water drinking and urination.
- Angiotensin-converting enzyme inhibitors (ACEIs). Drugs that improve the body’s ability to reduce salt and water retention, to reduce high blood pressure, and to limit the effect of hormones that adversely affect heart muscle
- Antiarrhythmic agents. May be given to stabilize the cardiac rate and rhythm.
- Drugs and nutritional supplements. Drugs to decrease blood pressure and nutritional supplements may be required for specific conditions.
Controlling the symptoms of heart failure
Low-salt (sodium) diets may be suggested. The kidney normally removes excess sodium, but this does not occur as effectively in heart failure. Commercial low-salt diets, varying from moderate to extreme restriction, are effective in preventing salt and water retention.
These diets are recommended only after heart failure has been diagnosed. A modest reduction in salt intake may be indicated before the onset of heart failure. If the pet refuses to eat a commercial diet, low-salt foods can be prepared by the owner under veterinary direction.
Mixing low-salt diets with regular (high salt) diets or feeding snacks high in sodium is not recommended.
Longevity and quality of life in dogs with this disease varies with the severity of the valve damage and the amount of blood leakage into the upper chambers of the heart.
Pre-existing medical conditions, age, and the physical status of the pet play a large role in determining the progression of the disease. Clinical signs are progressive, and although they may be decreased, they never entirely resolve. Medical therapy can enhance the quality of life of the pet as well as increase life expectancy. Dogs with left sided valvular heart disease treated with medication and a low-salt diet have an average life expectancy of about 9 months from the time heart failure begins. However, many do a lot longer.
Abdominal fluid accumulation and body emaciation are signs of right-sided heart failure. Regularly removing the extra fluid may increase life expectancy. Surgical replacement of the valves is not an option in dogs at this time.
If at any time you are concerned that your pet is showing signs of heart failure you should contact the practice immediately for advice.
During routine consultations such as yearly vaccinations the veterinarian will assess your pets heart health by:
- asking questions regarding exercise and sleeping patterns.
- listening to the rate and rhythm of the heart with a stethoscope
- feeling how strong the pulse is
- assessing the colour of the mucous membranes in the mouth
- asssessing how quickly blood will flow back into the tissue of the gum after pressure is placed on the gum with a finger (called capillary refill time).
- sometimes the vet or nurse may also take your pets blood pressure