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Heart Disease in Pets
Heart conditions are common in older pets. With the right management many animals live well for months or years — but understanding the stages helps you make good decisions.
Common Cardiac Conditions
Mitral Valve Disease (dogs)
The most common heart disease in dogs, especially small breeds — Cavalier King Charles Spaniels, Dachshunds, and Poodles are particularly prone. The mitral valve, which separates the left atrium from the left ventricle, becomes thickened and leaky. Blood flows backwards, the heart enlarges, and eventually congestive heart failure develops.
Dilated Cardiomyopathy (dogs)
More common in large breeds — Dobermanns, Great Danes, Irish Wolfhounds. The heart muscle weakens and the heart enlarges, reducing its ability to pump effectively. Can cause sudden death without prior symptoms.
Hypertrophic Cardiomyopathy (cats)
By far the most common heart condition in cats. The heart muscle thickens (hypertrophies), reducing the volume of the ventricles and impairing filling. Maine Coons and Ragdolls are genetically predisposed. Can affect cats of any age and often presents with no warning signs until crisis.
Signs & Symptoms
Exercise intolerance
Tiring quickly on walks, reluctance to exercise, needing to stop and rest more than usual.
Coughing (dogs)
A soft, persistent cough — often worse at night or after exercise. A sign of fluid accumulating around the lungs.
Increased breathing rate
Breathing faster than normal, even at rest. Counting breaths per minute at rest is a valuable home monitoring tool.
Laboured breathing
Open-mouth breathing, extended neck, elbows turned out — these are emergency signs.
Reduced appetite
Decreased interest in food, weight loss, or a distended abdomen (fluid accumulation).
Weakness or collapse
Fainting episodes, sudden weakness, or collapse — particularly during or after exercise.
Hiding (cats)
Cats often hide when unwell. Combined with other signs, this warrants urgent investigation.
Pale gums
A sign of poor circulation. Gums should be a healthy pink — pale, white, or blue gums require immediate veterinary attention.
Diagnosis & Staging
Cardiac disease is staged using the ACVIM (American College of Veterinary Internal Medicine) classification:
High risk of developing heart disease but no structural changes yet. Monitoring only.
Structural disease present (e.g. a murmur) but no enlargement and no symptoms.
Structural disease with heart enlargement but still no symptoms. Medication now recommended for dogs.
Congestive heart failure — fluid accumulation, symptoms present. Active medical management required.
End-stage. Refractory heart failure that does not respond adequately to standard treatment.
Diagnosis involves auscultation (listening), chest X-ray, echocardiography (ultrasound of the heart), ECG, and blood pressure measurement. Biomarkers (NT-proBNP, troponin) can assist in monitoring.
Management
Cardiac disease cannot be cured but can be well managed for substantial periods. Treatment depends on stage and species:
- ▸Pimobendan: The cornerstone of treatment for dogs with MVD at Stage B2 and above. Improves heart function and extends survival significantly.
- ▸Diuretics (frusemide): Remove fluid from the lungs in congestive heart failure. Life-saving in acute episodes.
- ▸ACE inhibitors: Reduce the workload on the heart. Used in combination with other medications in Stage C.
- ▸Dietary management: Reduced sodium diets and careful weight management. Adequate protein intake is important — do not restrict protein in cardiac patients.
- ▸Exercise restriction: Moderate, controlled exercise. Avoid anything that causes respiratory distress. No strenuous activity.
Quality of Life & End Stage
When heart failure progresses to Stage D — refractory to maximum medication — quality of life declines significantly. Signs that end-stage is being reached include: persistent difficulty breathing, inability to rest comfortably in any position, frequent acute episodes despite medication, severe exercise intolerance that prevents normal activities, and a pet who is clearly distressed or frightened by their own breathlessness.
Breathing difficulties are frightening for both pet and owner. When a pet cannot breathe comfortably, every moment is stressful. This is an important factor when considering quality of life.
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