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Vet Column
2025-12-24
A Complete Guide to Heart Disease in Cats and Dogs: Recognizing Warning Signs in Daily Life
This article was written by Dr. Shang-Hsiu Chung, a veterinarian at Always Care Veterinary Hospital
Have you noticed your cat or dog becoming unusually lethargic or less active, showing rapid breathing, coughing, or even suddenly collapsing during a walk?These seemingly minor day-to-day changes can be early warning signs of underlying heart problems—particularly cardiomyopathy.
Without timely intervention, such conditions may progress rapidly and become life-threatening.
This article will guide you through the most common heart diseases in cats and dogs, explain how to recognize heart-related issues through everyday abnormalities, and offer care and supplement recommendations to help safeguard your pet’s critical window of heart health.
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Before diving into heart disease, it’s helpful to understand how the hearts of cats and dogs differ from those of humans.
Like us, pets have four chambers—two atria and two ventricles—and their hearts function in a similar way.
However, their heart rates are significantly faster: a resting cat’s heart typically beats between 140 and 220 times per minute, while dogs range from 60 to 160 beats per minute, depending on size.
Because cats and dogs cannot clearly express discomfort, many heart conditions remain silent in the early stages.
This makes careful observation and routine checkups essential.
Proactive heart care and early intervention are key to preventing serious complications and safeguarding your pet’s health.
Common Cardiomyopathies in Cats and Dogs and Their Symptoms
1.Hypertrophic Cardiomyopathy (HCM) – The Silent Threat in CatsHCM is the most prevalent heart disease in cats, accounting for nearly 90% of all feline cardiomyopathies.
This condition involves thickening of the heart muscle walls and a reduction in the size of the left ventricular chamber, which diminishes cardiac output.
Over time, it can progress to congestive heart failure or lead to arterial thromboembolism.
Genetic factors play a significant role, particularly mutations in the MYBPC3 gene.
High-risk breeds include Maine Coon, Ragdoll, American Shorthair, British Shorthair, Persian, Bengal, Sphynx, and Norwegian Forest cats.
Typical symptoms may include rapid or labored breathing (often linked to pulmonary edema), lethargy, loss of appetite, and, in severe cases, sudden hind-leg paralysis caused by arterial thromboembolism—or even unexpected sudden death without prior warning.
2. Dilated Cardiomyopathy (DCM) – A High-Risk Condition in Dogs
DCM is a common heart disease in dogs, particularly in large breeds.
It is characterized by ventricular dilation, thinning of the heart muscle, and weakened contractions, all of which significantly reduce cardiac output.
This condition is most frequently observed in Dobermans, Great Danes, German Shepherds, Golden Retrievers, and Labradors.
In Dobermans, DCM has been linked to TTN and PDK4 gene mutations, although many cases remain idiopathic with no clearly identified cause.
Typical symptoms include:
- Reduced exercise tolerance and fatigue
- Persistent coughing or wheezing (often after activity or at night)
- Bluish discoloration of the nose or tongue
- Irregular heart rhythms (arrhythmias)
- Sudden fainting episodes
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These signs warrant immediate veterinary evaluation, as DCM can progress rapidly and lead to life-threatening complications.
Diagnostic Methods for Cardiomyopathy
Accurate diagnosis of cardiomyopathy typically requires a combination of diagnostic tools:- Auscultation: Initial evaluation to detect heart murmurs or irregular rhythms.
- Chest X-rays: Assess heart size and identify potential lung edema.
- Echocardiography: The gold standard for confirming diagnosis, providing detailed measurements of ventricular wall thickness, chamber size, and systolic function.
- Electrocardiogram (ECG): Used to evaluate arrhythmias and electrical activity.
- Blood Tests: Biomarkers such as NT-proBNP and cardiac troponin help detect myocardial stress or injury.
- Thyroid Function Tests: Performed to rule out secondary causes of heart disease.
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ACVIM Staging System (Stages A–D)
Veterinarians use the ACVIM system to classify disease severity and guide treatment:
- Stage A: High-risk breeds with no structural changes.
- Stage B: Structural heart changes without clinical symptoms.
B2: Moderate to severe left atrial enlargement; higher risk.
- Stage C: Current or previous signs of heart failure.
- Stage D: End-stage disease with refractory symptoms. (illustration)
Treatment and Daily Care Recommendations
Although cardiomyopathy cannot be cured, appropriate treatment and attentive care can slow disease progression and significantly improve quality of life.- Veterinary Management: Medications are prescribed based on ACVIM staging to control symptoms, support cardiac function, and stabilize overall health.
- Home Monitoring: Owners should regularly check their pet’s breathing rate and general vitality. A resting respiratory rate should remain below 40 breaths per minute. If you notice rapid breathing, persistent fatigue, or decreased activity, seek immediate veterinary attention.
Daily Supplements and Nutrition
Beyond medication, proper nutrition plays a critical role in supporting heart health for pets with cardiac disease. The guiding principles are:“low sodium, high-quality protein, and targeted supplements for dogs and cats to maintain cardiac function, optimize energy metabolism, and reduce inflammation and oxidative stress.
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Dietary Management Principles
- Low-sodium diet: Select prescription diets labeled as low-salt to minimize fluid retention and reduce cardiac workload.
- Balanced nutrition: Avoid relying solely on natural ingredients; ensure complete and balanced diets for adequate nutrient intake.
- High-quality protein: Supports myocardial repair and overall strength; avoid salty or processed meats.
- Natural antioxidant sources: Include vegetables and fruits such as pumpkin, spinach, blueberries to help combat free-radical damage.
- Avoid processed foods: Steer clear of salty treats, fried foods, and canned meats, as these can increase cardiac strain.
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Key Supplements for Dogs and Cats:
- Taurine: Essential for myocardial contraction and cardiac rhythm stability; particularly critical for cats. Naturally present in chicken liver and fish.
- L-Carnitine: Supports cardiac energy metabolism and fatty acid utilization; commonly found in beef and fish.
- Omega-3 Fatty Acids (EPA/DHA): Exert anti-inflammatory effects and help maintain vascular elasticity; sourced from salmon and fish oil.
- Coenzyme Q10: Plays a key role in cellular energy production and antioxidant defense; best supplemented through pet-specific formulations.
- Vitamin E & Astaxanthin: Potent antioxidants that help reduce oxidative myocardial damage and support overall cardiovascular health.
Although cardiomyopathy cannot be cured, early detection, accurate diagnosis, and regular follow-up care can significantly slow disease progression and improve quality of life.
Both feline hypertrophic cardiomyopathy (HCM) and canine dilated cardiomyopathy (DCM) require ongoing monitoring and attentive management.
In addition to pharmacologic treatment, a balanced, low-sodium diet combined with targeted supplements for dogs and cats can support cardiac function and help pets safely navigate each stage of the disease.
Choosing the right heart supplements for dogs and cats is essential—understanding formulation differences and selecting clinically supported ingredients can strengthen the heart from within and reduce risks. Let’s take action to protect our pets’ heart health and accompany them safely every day.
FAQ
Q1: Why has my cat or dog become lethargic and less active? Could this indicate a heart problem?
A: Decreased energy levels and reduced activity are common but often overlooked early signs of heart disease. When cardiac output declines, oxygen delivery to tissues is compromised, prompting pets to conserve energy by limiting movement. If these changes persist for several days—particularly in high-risk breeds—a veterinary cardiac evaluation is strongly recommended.
Q2: I’ve noticed my pet breathing rapidly at rest, with pronounced chest movement. Is this a warning sign?
A: Yes. A resting respiratory rate exceeding 40 breaths per minute is concerning and may indicate pulmonary edema or cardiac overload. Panting in cats is particularly dangerous and often signals an acute cardiac emergency that requires immediate veterinary attention.
Q3: My dog has developed a frequent cough. Is it a cold or could it be heart disease?
A: Heart-related coughs often worsen at night or after exercise and may be accompanied by rapid breathing, exercise intolerance, or fatigue. If the cough persists or progresses, chest radiography and a cardiac evaluation are recommended to assess for heart enlargement or pulmonary edema.
Q4: My cat suddenly cannot use its hind legs. Could this be related to heart disease?
A: Yes. This presentation may indicate arterial thromboembolism, a serious and relatively common acute complication of hypertrophic cardiomyopathy (HCM). Affected cats may develop sudden hind-limb paralysis, cold extremities, and severe pain or vocalization. This is a life-threatening emergency that requires immediate veterinary intervention.
Q5: My pet suddenly sits down, pants excessively during walks, or even briefly faints. Could this indicate heart disease?
A: These signs are commonly associated with reduced cardiac output or underlying arrhythmias. When the heart is unable to supply adequate blood and oxygen to the body, pets may experience weakness, exercise intolerance, or syncope. Prompt evaluation with electrocardiography and cardiac ultrasound is strongly recommended.
Q6: Should pets with heart disease follow a low-sodium diet? Is regular pet food acceptable?
A: Yes. Sodium restriction helps reduce fluid retention and decreases cardiac workload, making it an important component of management for most pets with heart disease. Many standard commercial pet foods contain relatively high sodium levels. A veterinarian-recommended low-sodium or prescription cardiac diet is therefore advised, and salty treats or processed meats should be strictly avoided.
Q7: There are many heart-health supplements on the market—how should I choose?
A: Look for supplements that contain clinically supported ingredients such as taurine, L-carnitine, Omega-3 fatty acids (EPA/DHA), Coenzyme Q10, vitamin E, and astaxanthin. These nutrients help support cardiac metabolism, stabilize heart rhythm, and reduce inflammation and oxidative stress. Most importantly, select products formulated specifically for pets with clearly indicated dosages, and consult your veterinarian to ensure safe and effective use.
Q8: Can pets without heart disease take heart-health supplements preventively?
A: Yes. Preventive supplementation can benefit high-risk breeds, senior pets, overweight animals, or those with lower activity levels. Nutrients such as taurine, L-carnitine, and Omega-3 fatty acids may help support heart function before cardiac stress develops. However, supplements do not replace regular veterinary checkups, and any signs such as abnormal breathing, coughing, or fatigue should prompt immediate veterinary evaluation.
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