Dog Heart Disease
Heart disease affects approximately 10-15% of all dogs, with rates much higher in senior dogs and certain breeds. While heart disease is serious, many dogs with cardiac conditions can live comfortable lives for years with proper management. This resource covers the types, symptoms, and treatment of heart disease in dogs.
Emergency Signs - Seek Immediate Care
- Severe difficulty breathing (gasping, extended neck)
- Blue or purple tongue/gums
- Collapse or fainting
- Sudden inability to stand or walk
- Coughing up pink, foamy fluid
- Extreme weakness or unresponsiveness
These may indicate heart failure or a cardiac emergency. Go to an emergency veterinarian immediately.
Degenerative Valve Disease (Mitral Valve Disease)
The most common heart disease in dogs, accounting for 75% of cases.
- What happens: Heart valves thicken and leak, causing blood to flow backward
- Progression: Slowly worsens over months to years
- Most affected: Small breeds, older dogs
- Breeds at high risk: Cavalier King Charles Spaniels, Dachshunds, Chihuahuas, Miniature Poodles, Cocker Spaniels
Dilated Cardiomyopathy (DCM)
The heart muscle weakens and the heart enlarges, reducing pumping ability.
- What happens: Heart chambers dilate and walls thin
- Progression: Can progress rapidly once symptoms appear
- Most affected: Large and giant breeds
- Breeds at high risk: Doberman Pinschers, Great Danes, Boxers, Irish Wolfhounds, Cocker Spaniels
- Note: Some cases linked to grain-free diets (DCM-diet association under investigation)
Congenital Heart Defects
Heart abnormalities present from birth.
- Patent Ductus Arteriosus (PDA): Abnormal vessel between aorta and pulmonary artery
- Pulmonic Stenosis: Narrowing of the pulmonary valve
- Subaortic Stenosis: Narrowing below the aortic valve
- Ventricular Septal Defect: Hole between heart chambers
Arrhythmias
Abnormal heart rhythms that can be primary or secondary to other heart disease.
- Atrial fibrillation
- Ventricular tachycardia
- Heart block
Heartworm Disease
Parasitic worms living in the heart and pulmonary arteries.
- Cause: Transmitted by mosquitoes
- Prevention: Monthly preventatives are highly effective
- Treatment: Complex and risky; prevention is crucial
Pericardial Disease
Fluid accumulation around the heart.
- Can be caused by tumors, infection, or unknown causes
- Restricts heart's ability to fill properly
Early Signs (Often Subtle)
- Slight decrease in activity or stamina
- Tiring more quickly on walks
- Occasional coughing (especially at night or after excitement)
- Mild weight loss
- Heart murmur detected at routine exam
Progressive Signs
- Coughing: Persistent, especially at night or when lying down
- Exercise intolerance: Reluctance to walk or play
- Rapid or labored breathing: Even at rest
- Restlessness at night: Unable to get comfortable
- Weight loss: Muscle wasting despite appetite
- Fainting (syncope): Brief collapse episodes
- Abdominal distension: Fluid accumulation (ascites)
Signs of Congestive Heart Failure
- Severe difficulty breathing
- Persistent cough, especially producing pink foam
- Blue or gray gums/tongue
- Extreme weakness
- Collapse
- Swollen belly (fluid accumulation)
- Reluctance to lie down (air hunger)
Physical Examination
- Heart murmur: Abnormal sounds heard with stethoscope
- Arrhythmia: Irregular heartbeat
- Lung sounds: Crackles indicating fluid
- Pulse quality: Weak or irregular pulses
Diagnostic Tests
| Test | What It Shows |
|---|---|
| Chest X-rays | Heart size, lung congestion, fluid accumulation |
| Echocardiogram (ultrasound) | Heart structure, valve function, pumping ability - gold standard |
| Electrocardiogram (ECG) | Heart rhythm, arrhythmias |
| Blood pressure | High or low blood pressure |
| Blood tests | Cardiac biomarkers (proBNP, troponin), organ function |
| Heartworm test | Rule out heartworm disease |
Staging Heart Disease
The ACVIM (American College of Veterinary Internal Medicine) uses these stages.
- Stage A: At risk but no disease detected yet
- Stage B1: Heart disease present, no symptoms, heart not enlarged
- Stage B2: Heart disease with heart enlargement, no symptoms yet
- Stage C: Heart failure - symptoms present or have occurred
- Stage D: End-stage heart failure, resistant to standard treatment
Medications
Common Heart Medications
| Medication | Purpose | Notes |
|---|---|---|
| Pimobendan (Vetmedin) | Strengthens heart contraction, dilates blood vessels | Often first-line for heart failure; proven to extend life |
| Furosemide (Lasix) | Removes fluid (diuretic) | Essential for congestion; dose adjusted based on symptoms |
| Enalapril/Benazepril (ACE inhibitors) | Reduces blood pressure, helps heart work easier | May slow disease progression |
| Spironolactone | Mild diuretic, blocks harmful hormones | Often combined with furosemide |
| Digoxin | Controls heart rate, mild strengthening | Used for atrial fibrillation; requires monitoring |
| Diltiazem/Atenolol | Controls heart rate | For certain arrhythmias |
Medication Tips
- Give medications at the same times daily
- Never skip or double doses without veterinary guidance
- Some medications require regular blood tests
- Report any side effects (decreased appetite, vomiting, diarrhea)
Dietary Management
- Sodium restriction: Low-sodium diet to reduce fluid retention
- Adequate protein: Maintain muscle mass
- Omega-3 fatty acids: May have heart-protective effects
- Taurine/L-carnitine: Supplementation in certain breeds or DCM cases
- Maintain healthy weight: Obesity stresses the heart; cachexia (wasting) is also dangerous
Surgical Options
- Mitral valve repair: Available at specialized centers; can be curative for valve disease
- Pacemaker implantation: For certain arrhythmias and heart block
- PDA ligation: Surgical correction of patent ductus arteriosus
- Balloon valvuloplasty: For pulmonic stenosis
- Pericardiocentesis: Draining fluid from around the heart
Monitoring at Home
- Resting respiratory rate (RRR): Count breaths per minute while sleeping (normal <30); increase may indicate worsening
- Activity level: Note changes in stamina
- Appetite and weight: Track regularly
- Coughing episodes: Frequency and severity
- Overall demeanor: Alertness, willingness to engage
Lifestyle Modifications
- Keep environment cool (heat stresses the heart)
- Avoid strenuous exercise; gentle walks are usually okay
- Maintain consistent routine
- Ensure easy access to water
- Consider elevated food/water bowls if swallowing is difficult
- Avoid stress when possible
Exercise Guidelines
- Follow your cardiologist's specific recommendations
- Short, gentle walks are usually beneficial
- Avoid extreme temperatures
- Let your dog set the pace
- Stop if breathing becomes labored
- Some dogs do better with multiple short walks vs. one long one
Prognosis
Prognosis varies widely based on the type and stage of heart disease.
Degenerative Valve Disease
- Many dogs live for years with heart murmurs before developing symptoms
- Stage B2: Studies show pimobendan delays heart failure by ~15 months
- Stage C: Median survival with treatment is 6-18 months, though some do much better
Dilated Cardiomyopathy
- More guarded prognosis, especially in Dobermans
- Some dogs respond well to treatment and live 1-2+ years
- Early detection through screening improves outcomes
Congenital Defects
- Varies based on defect type and severity
- Some are surgically correctable with excellent outcomes
Prevention
Treating their dog as its own animal, not a stand-in for the category, tends to improve every decision that follows.
Heartworm Prevention
- Year-round monthly preventatives
- Annual heartworm testing
- Heartworm disease is preventable but difficult and dangerous to treat
Breed Screening
- Breeders should screen for heart disease in predisposed breeds
- Cavalier King Charles Spaniels: Annual cardiac exams recommended
- Dobermans: Annual Holter monitoring and echocardiograms
General Heart Health
- Maintain healthy weight
- Regular exercise appropriate for your dog
- Quality nutrition
- Regular veterinary check-ups (heart murmurs can be detected early)
- Dental care (dental disease bacteria can affect the heart)
Ask About Heart Disease
Have questions about your dog's heart health or managing heart disease? Our AI assistant can help you understand symptoms, treatments, and what to discuss with your veterinarian.