Instruction: how to tell if a dog has heart problems.

Introduction

Understanding Canine Heart Health

The Importance of Early Detection

Early detection of canine cardiac disease dramatically improves treatment options and survival rates. Veterinary cardiology specialists observe that dogs diagnosed at the first signs of heart dysfunction respond better to medication, lifestyle adjustments, and surgical interventions.

Common early indicators include:

Persistent cough, especially at night or after exercise
Reduced stamina or reluctance to play
Noticeable weight loss despite normal appetite
Swelling in the abdomen or limbs
Irregular heartbeat detected by auscultation or home monitoring devices

Diagnostic protocols rely on objective measurements rather than anecdotal observation. Standard procedures comprise:

Auscultation by a qualified veterinarian to identify murmurs or arrhythmias
Thoracic radiographs to assess heart size and pulmonary fluid
Echocardiography for precise evaluation of chamber dimensions and valve function
Electrocardiography to document electrical activity and rhythm abnormalities
Blood tests for biomarkers such as NT‑proBNP that correlate with cardiac stress

Advantages of confirming heart disease before severe progression are quantifiable:

Lower drug dosages achieve therapeutic effect, reducing side‑effects
Surgical procedures, when needed, carry reduced operative risk
Quality of life improves as pain and fatigue diminish
Owners receive clear prognosis, enabling informed decisions about care and breeding

Veterinarians advise routine wellness exams for all breeds, with increased frequency for those predisposed to cardiac conditions. Incorporating periodic heart assessments into preventive health plans ensures that subtle changes are captured promptly, allowing timely intervention and extending the animal’s productive years.

Common Heart Conditions in Dogs

Congenital Heart Diseases

Congenital heart diseases (CHDs) are structural abnormalities present at birth that can impair cardiac function in dogs. Recognizing CHDs early improves prognosis and guides treatment decisions.

Typical presentations include:

Persistent coughing, especially after exercise or at night
Rapid, shallow breathing or difficulty recovering from activity
Noticeable fatigue or reluctance to play
Abnormal heart sounds such as murmurs detected during routine examination
Fainting episodes or sudden collapse without obvious cause
Swelling of the abdomen or limbs due to fluid accumulation

Diagnostic approach:

Auscultation by a veterinarian to identify murmurs, arrhythmias, or abnormal rhythm.
Thoracic radiographs to assess heart size, pulmonary vessels, and evidence of fluid in the lungs.
Electrocardiography for rhythm analysis and detection of conduction abnormalities.
Echocardiography, the definitive tool, visualizes chamber dimensions, valve integrity, and blood flow patterns, confirming specific CHD types such as patent ductus arteriosus, pulmonic stenosis, or subaortic stenosis.
Blood pressure measurement to detect systemic hypertension that may accompany certain defects.

Management strategies depend on the specific defect:

Surgical ligation or catheter-based closure for patent ductus arteriosus.
Balloon valvuloplasty for stenotic lesions.
Medical therapy (e.g., diuretics, ACE inhibitors, anti‑arrhythmic drugs) to control symptoms when surgery is not feasible.

Regular monitoring, including repeat auscultation and imaging, tracks disease progression and treatment efficacy. Early identification of congenital anomalies through careful observation of respiratory and exercise tolerance signs, combined with targeted diagnostic testing, enables timely intervention and improves long‑term outcomes for affected dogs.

Acquired Heart Diseases

Valvular Disease

Valvular disease is a leading cause of cardiac dysfunction in dogs. The condition involves degeneration, inflammation, or congenital malformation of the heart valves, most commonly the mitral and tricuspid valves. When the valves fail to close properly, blood regurgitates, producing characteristic clinical signs that help differentiate valvular pathology from other cardiac disorders.

Typical manifestations include:

Murmurs: Low‑frequency, systolic murmurs audible at the left apex (mitral) or right sternal border (tricuspid).
Exercise intolerance: Reduced stamina, reluctance to run or play, especially in hot weather.
Coughing: Dry, persistent cough caused by pulmonary congestion secondary to backward flow.
Respiratory distress: Rapid or labored breathing, especially when lying down.
Abdominal distension: Accumulation of fluid (ascites) due to right‑sided overload.
Weak pulse: Diminished peripheral perfusion detectable on palpation.

Diagnostic confirmation relies on objective assessments:

Auscultation: Precise identification of murmur timing, intensity, and location.
Radiography: Evaluation of cardiac silhouette enlargement, pulmonary vasculature, and pleural effusion.
Echocardiography: Direct visualization of valve structure, measurement of regurgitant jet, and calculation of fractional shortening.
Electrocardiography: Detection of arrhythmias or chamber enlargement patterns.
Blood work: Exclusion of systemic diseases that may mimic cardiac signs; measurement of NT‑proBNP for cardiac stress.

Management decisions stem from severity grading. Mild regurgitation without clinical signs may require only periodic monitoring. Moderate to severe cases often need pharmacologic intervention-angiotensin‑converting enzyme inhibitors, diuretics, and positive inotropes-to reduce preload, control fluid accumulation, and improve contractility. In advanced stages, surgical valve replacement or repair may be considered, though availability is limited.

Early recognition of valvular disease hinges on vigilant observation of the listed signs and prompt veterinary evaluation using the outlined diagnostic tools. Consistent follow‑up enables timely treatment adjustments, prolonging quality of life for affected dogs.

Myocardial Disease

Myocardial disease in dogs refers to any condition that impairs the contractile function of the heart muscle, leading to reduced cardiac output and potential progression to heart failure.

Common causes include genetic cardiomyopathies, inflammatory processes such as myocarditis, nutritional deficiencies, toxic exposures, and secondary involvement from systemic illnesses.

Clinical manifestations that suggest myocardial involvement are exercise intolerance, rapid or irregular breathing, cough that worsens at night, fainting episodes, and abdominal distension due to fluid accumulation.

During physical examination, a veterinarian may detect a weak, thready pulse, a low systolic blood pressure, an irregular heart rhythm, a shortened or absent heart sound, and a displaced point of maximal impulse.

Diagnostic tools that confirm myocardial disease comprise:

Resting electrocardiogram to identify arrhythmias or conduction abnormalities.
Thoracic radiographs to assess heart size, pulmonary vasculature, and pleural effusion.
Echocardiography for direct measurement of ventricular wall thickness, chamber dimensions, and systolic function.
Blood biomarkers such as cardiac troponin I and N‑terminal pro‑BNP to evaluate myocardial injury and stress.
Endomyocardial biopsy when definitive histopathology is required.

Interpretation of these results focuses on identifying reduced fractional shortening, increased left ventricular end‑diastolic dimension, elevated biomarkers, and evidence of arrhythmias, all of which confirm compromised myocardial performance.

Therapeutic strategies aim to reduce cardiac workload, control arrhythmias, and manage fluid accumulation. First‑line medications include ACE inhibitors, diuretics, and positive inotropes; anti‑arrhythmic agents are added when rhythm disturbances are documented. Regular monitoring of cardiac dimensions and biomarker trends guides dosage adjustments and prognostic assessment.

Early recognition of myocardial disease, combined with systematic diagnostic evaluation, enables timely intervention and improves the likelihood of stabilizing cardiac function in affected dogs.

Arrhythmias

Arrhythmias represent irregular electrical activity in the canine heart and are a common indicator of cardiac dysfunction. Detectable signs include:

Irregular pulse felt at the femoral or carotid artery
Episodes of fainting or collapse (syncope)
Sudden weakness or lethargy after exercise
Unexplained coughing, especially at rest
Abnormal heart sounds such as skipped beats or extra beats during auscultation

Physical examination may reveal a variable rhythm when the veterinarian auscultates the thorax. Palpation of the peripheral pulse can confirm irregular intervals between beats. Inconsistent pulse pressure often accompanies ventricular arrhythmias, while atrial arrhythmias may produce a regular pulse but abnormal heart sounds.

Electrocardiography (ECG) provides definitive confirmation. A standard 6‑lead ECG records the timing and morphology of each cardiac cycle, allowing classification of arrhythmias into sinus arrhythmia, atrial fibrillation, ventricular premature complexes, or more severe tachyarrhythmias. Holter monitoring extends observation to 24‑48 hours, capturing intermittent episodes that a brief ECG might miss.

Blood tests help identify underlying causes. Elevated troponin suggests myocardial injury; electrolyte imbalances (potassium, calcium) can precipitate rhythm disturbances. Thyroid hormone levels, especially in older breeds, are relevant because hyperthyroidism may trigger tachyarrhythmias.

Imaging, such as thoracic radiographs and echocardiography, assesses structural heart disease that often coexists with electrical abnormalities. Enlargement of the left atrium or ventricular dilation supports a diagnosis of chronic arrhythmia secondary to cardiomyopathy.

Management decisions depend on the arrhythmia type, frequency, and clinical impact. Antiarrhythmic drugs (e.g., lidocaine, amiodarone) are prescribed based on ECG findings. In cases of severe ventricular tachycardia, electrical cardioversion may be required. Lifestyle adjustments-moderate exercise, avoidance of stressors, and regular monitoring-reduce the risk of sudden decompensation.

Early recognition of arrhythmic patterns, combined with targeted diagnostics, enables timely intervention and improves prognosis for dogs with heart problems.

Recognizing the Signs of Heart Problems

Behavioral Changes

Lethargy and Weakness

Lethargy and weakness often signal cardiac compromise in dogs. A dog that suddenly reduces activity, shows reluctance to rise, or appears unable to sustain normal walking may be experiencing reduced cardiac output. Observe the following indicators:

Decreased willingness to play or go for walks, especially after minimal exertion.
Slow, unsteady gait or frequent stumbling when attempting to stand.
Noticeable fatigue after short periods of activity that previously required no effort.
Reduced responsiveness to stimuli, such as delayed reaction to calls or commands.

These signs differ from typical age‑related slowing because they develop rapidly and are accompanied by other systemic changes. Evaluate duration and progression: symptoms persisting for more than 24‑48 hours or worsening within a day warrant immediate veterinary assessment. Concurrent findings-such as coughing, rapid breathing, or pale gums-strengthen the suspicion of heart disease.

When assessing lethargy, rule out non‑cardiac causes (pain, infection, metabolic disorders) by checking temperature, pulse quality, and mucous membrane color. A weak, thready pulse combined with the above behavioral changes strongly suggests cardiac insufficiency. Prompt diagnostic work‑up, including auscultation, chest radiographs, and echocardiography, is essential to confirm the diagnosis and initiate appropriate treatment.

Reduced Stamina

Reduced stamina often signals underlying cardiac insufficiency in dogs. When a normally active canine suddenly tires after brief walks or refuses to engage in play, the heart may be failing to deliver adequate oxygenated blood to muscles. This change in endurance is observable without specialized equipment.

Veterinarians recommend monitoring the following indicators:

Shortness of breath after minimal exertion
Reluctance to climb stairs or jump onto furniture
Decreased willingness to run or fetch
Noticeable panting that persists after activity stops

If any of these signs appear, assess the dog's pulse at the femoral artery. A rapid, weak pulse combined with low stamina strengthens suspicion of cardiac compromise. Record the heart rate for several minutes at rest; values consistently above 120 beats per minute in a resting dog warrant further evaluation.

Prompt veterinary examination is essential. Diagnostic tools such as thoracic radiographs, echocardiography, and blood tests for cardiac biomarkers provide definitive confirmation. Early detection through observation of diminished endurance improves treatment outcomes and quality of life.

Changes in Appetite

When a dog’s eating habits shift, the change can be a direct clue that the cardiovascular system is under strain. Cardiac insufficiency reduces blood flow to the gastrointestinal tract, impairing nutrient absorption and creating a sensation of early fullness. Consequently, many owners notice a sudden drop in food intake or a reluctance to finish meals that were previously accepted without hesitation.

Key patterns to watch for include:

Consistent refusal of meals or a marked decrease in quantity consumed.
Rapid weight loss despite unchanged feeding schedule.
Preference for softer or wetter foods, suggesting difficulty swallowing dry kibble.
Episodes of vomiting after eating, often accompanied by a sour or blood‑tinged taste.
Increased thirst and urination that accompany reduced appetite, reflecting fluid retention.

These behaviors do not occur in isolation. A dog with emerging heart disease may also display lethargy, labored breathing, or a cough. The combination of reduced appetite with any of those signs strengthens the suspicion of cardiac involvement.

If appetite alteration persists for more than 24‑48 hours, a veterinary evaluation is warranted. The clinician will typically perform:

Physical examination focusing on heart rate, rhythm, and peripheral pulses.
Thoracic radiographs to assess heart size and pulmonary congestion.
Echocardiography for direct visualization of cardiac function and chamber dimensions.
Blood work, including cardiac biomarkers such as NT‑proBNP, to quantify myocardial stress.

Early detection through careful monitoring of feeding behavior can accelerate diagnosis and enable timely therapeutic intervention, improving the dog’s quality of life and prognosis.

Physical Symptoms

Persistent Cough

Persistent cough is one of the most reliable clinical clues that a dog may be experiencing cardiac dysfunction. When the left ventricle fails to pump efficiently, fluid accumulates in the pulmonary vessels, leading to pulmonary edema and irritation of the airway. The resulting cough often persists despite rest and may worsen at night or after exertion.

Key observations for evaluating a cough of cardiac origin include:

Dry, hacking sound without mucus production.
Frequency of several bouts per hour, lasting weeks to months.
Intensification during or after physical activity.
Absence of improvement with environmental changes (e.g., humidity control).
Co‑occurrence of exercise intolerance, rapid breathing, or fainting episodes.

Diagnostic protocol recommended by veterinary cardiology experts:

Thorough physical examination focusing on heart rate, rhythm, and murmur detection.
Thoracic radiographs to identify pulmonary edema, enlarged cardiac silhouette, or pleural effusion.
Echocardiography to assess chamber size, wall thickness, and valvular competence.
Blood work, including cardiac biomarkers (e.g., NT‑proBNP), to support cardiac involvement.
Electrocardiogram for rhythm abnormalities that may accompany structural disease.

Management strategies target the underlying heart condition rather than the cough alone. Therapeutic measures typically involve:

Diuretics to reduce pulmonary fluid buildup.
ACE inhibitors or angiotensin receptor blockers to decrease afterload.
Positive inotropes if systolic function is compromised.
Controlled exercise programs to limit stress on the cardiovascular system.

Only after confirming a cardiac cause should adjunctive cough suppressants be considered, and they must be selected to avoid depressing respiratory drive. Persistent cough, when examined with the outlined criteria, provides a decisive indicator that further cardiac evaluation is warranted.

Difficulty Breathing (Dyspnea)

As a veterinary cardiologist, I focus on respiratory distress that often signals cardiac insufficiency in dogs. When a dog struggles to breathe, the underlying problem may be fluid accumulation in the lungs, reduced cardiac output, or compromised airway structures caused by heart enlargement.

Key observations include:

Rapid, shallow breaths or prolonged inhalation/exhalation cycles.
Audible wheezing or crackles heard with a stethoscope.
Gasping episodes, especially when the dog is at rest.
Noticeable effort to draw air, such as visible neck or abdominal muscle movement.
Coughing that worsens after activity or during the night.

These signs may appear suddenly or develop gradually. Acute onset often points to pulmonary edema, while chronic, mild dyspnea can indicate early heart failure. Assess the dog's posture; a dog lying on its side with the neck extended may be trying to ease airflow.

Physical examination should involve:

Auscultation of heart sounds for murmurs, gallops, or irregular rhythms.
Evaluation of lung fields for fluid, consolidation, or abnormal noises.
Palpation of peripheral pulses to gauge circulatory strength.
Measurement of respiratory rate and pattern over several minutes.

Diagnostic tools that confirm cardiac involvement include thoracic radiographs to reveal pulmonary congestion, echocardiography to assess chamber size and function, and blood tests for biomarkers such as NT‑proBNP. Electrocardiography helps identify arrhythmias that can exacerbate breathing difficulty.

Management strategies depend on the severity of the condition:

Mild dyspnea may respond to diuretics and low‑dose ACE inhibitors to reduce fluid overload.
Moderate to severe cases often require oxygen therapy, more aggressive diuretic regimens, and possible hospitalization.
Long‑term care involves regular monitoring, weight control, and medication adjustments to maintain optimal cardiac performance.

Immediate veterinary evaluation is warranted if the dog exhibits labored breathing, persistent coughing, or sudden collapse. Early detection and targeted treatment improve prognosis and quality of life for dogs with cardiac‑related respiratory distress.

Fainting or Collapse (Syncope)

Fainting or sudden collapse in a dog often signals an underlying cardiac disturbance. The event is typically brief, lasting seconds to a few minutes, and may recur without warning. Recognizing syncope requires careful observation of the episode’s context, duration, and recovery pattern.

Key indicators that a collapse may be heart‑related include:

Loss of consciousness accompanied by a rapid, weak pulse detectable at the femoral artery.
Presence of a murmur or abnormal heart sounds on auscultation before or after the episode.
Pale or grayish mucous membranes, suggesting reduced perfusion.
Weakness or stumbling immediately prior to the fall, often triggered by exertion, excitement, or sudden changes in temperature.
Absence of seizure activity such as paddling, vocalization, or post‑ictal disorientation; syncope typically resolves with the dog regaining full posture within a minute.

Diagnostic steps an experienced veterinarian would pursue are:

Record the event on video when possible to differentiate syncope from seizures.
Perform a thorough cardiac exam, including auscultation, blood pressure measurement, and electrocardiography.
Obtain thoracic radiographs or echocardiography to assess heart size, wall thickness, and valve integrity.
Run blood tests to rule out metabolic causes that can mimic cardiac collapse, such as hypoglycemia or electrolyte imbalance.

Management focuses on stabilizing the cardiovascular system and preventing recurrence. Treatment may involve anti‑arrhythmic drugs, pacemaker implantation for conduction disorders, or medication to reduce heart failure progression. Owners should limit high‑intensity activity, avoid overheating, and keep a log of any fainting episodes, noting triggers and recovery time. Prompt veterinary evaluation after the first episode improves prognosis and guides appropriate therapy.

Abdominal Swelling (Ascites)

Abdominal swelling, known as ascites, frequently signals underlying cardiac disease in dogs. Fluid accumulates in the peritoneal cavity when the heart cannot maintain adequate circulation, leading to increased venous pressure and transudation of plasma into the abdomen.

Observation begins with a visual and tactile assessment. The abdomen appears distended, often symmetrical, and may feel tense when pressed. Palpation reveals a fluid wave that moves across the surface as the dog shifts. In severe cases the skin over the belly may stretch, and the dog may adopt a crouched posture to accommodate the extra volume.

A systematic evaluation includes:

Thoracic auscultation to detect murmurs, gallops, or diminished heart sounds.
Measurement of heart rate and rhythm using a stethoscope or ECG.
Radiographs of the chest and abdomen to identify cardiomegaly, pulmonary congestion, and fluid lines.
Ultrasound examination of the heart to assess chamber size, contractility, and valve function; abdominal ultrasound confirms the presence and character of the fluid.
Analysis of the aspirated abdominal fluid for protein concentration, cell count, and cytology, distinguishing transudate (typical of heart failure) from exudate (suggestive of infection or neoplasia).

When ascites is confirmed as a consequence of cardiac insufficiency, treatment targets the heart condition. Diuretics reduce fluid volume, while ACE inhibitors and positive inotropes improve cardiac output. Dietary sodium restriction supports fluid management. Regular monitoring of weight, abdominal girth, and clinical signs ensures timely adjustment of therapy.

Recognizing ascites as an early indicator of cardiac compromise enables prompt diagnostic work‑up and intervention, improving prognosis for affected dogs.

Weight Changes

Weight fluctuations are a primary indicator when assessing canine cardiac health. Sudden loss of body condition often signals reduced cardiac output, while gradual weight gain may reflect fluid accumulation from congestive heart failure.

A rapid decline in appetite, coupled with visible muscle wasting, suggests the heart is unable to deliver sufficient nutrients to tissues. Conversely, a bloated abdomen, especially when the ribcage remains unchanged, points to fluid retention in the thoracic or abdominal cavities.

Key observations include:

Unexplained weight loss of more than 5 % of body mass within a few weeks.
Noticeable edema in the limbs or ventral abdomen.
Persistent swelling of the belly despite normal food intake.
Fluctuating weight that correlates with periods of increased activity or rest.

Monitoring should involve regular weigh‑ins using the same scale and conditions. Record the dog's weight at least weekly and compare trends over a month. Any deviation from the baseline, whether loss or gain, warrants veterinary evaluation.

Veterinarians may confirm cardiac involvement through diagnostic imaging, auscultation, and laboratory tests, but consistent weight monitoring provides the earliest practical clue that the heart may be compromised.

Pale Gums

Pale gums are a primary visual cue that a dog’s cardiovascular system may be compromised. The mucous membranes should appear pink, reflecting adequate blood flow; a noticeable loss of color suggests reduced oxygen delivery, often linked to heart dysfunction.

When examining a dog, gently lift the upper lip to expose the gum tissue. Observe the hue under natural light; gray, white, or bluish tones are abnormal. Compare the color to the inner eyelid, which should also be pink. If the gums are markedly lighter than the eyelid, the condition warrants immediate attention.

Key observations associated with pale gums include:

Rapid, shallow breathing
Weak or irregular pulse detectable at the femoral artery
Lethargy or reluctance to exercise
Episodes of fainting or collapse

If pale gums are detected, follow these steps:

Record the exact color and any accompanying symptoms.
Measure the heart rate and rhythm by palpating the femoral pulse for 30 seconds, then multiply by two.
Contact a veterinarian promptly, providing the recorded findings.
Keep the dog calm and limit physical activity until professional evaluation.

Early recognition of gum discoloration can prevent progression to severe heart failure, allowing timely diagnostic testing such as echocardiography or blood work.

When to Seek Veterinary Attention

The Urgency of Symptoms

When a canine cardiac condition progresses, the window for effective intervention narrows dramatically. Recognizing signs that demand immediate veterinary attention can prevent irreversible damage and increase survival odds.

Rapid breathing, especially at rest, indicates compromised circulation. A cough that intensifies during or after exercise suggests fluid accumulation in the lungs. Pale or bluish gums reflect insufficient oxygen delivery and require urgent assessment. Collapse, fainting, or sudden weakness signals acute heart failure. Unexplained lethargy combined with a noticeable decrease in appetite may precede decompensation.

Respiratory rate exceeding 30 breaths per minute while at rest
Persistent, dry cough that worsens with activity
Mucous membranes turning gray, white, or cyanotic
Episodes of syncope or sudden loss of consciousness
Marked fatigue, reluctance to move, and reduced food intake

Prompt veterinary evaluation, including auscultation, chest radiographs, and cardiac biomarkers, is essential once any of these indicators appear. Early diagnosis and targeted therapy, such as diuretics, ACE inhibitors, or pimobendan, can stabilize the condition and improve quality of life. Delaying care reduces treatment efficacy and raises the risk of fatal outcomes.

Preparing for the Vet Visit

When a dog may have cardiac disease, the veterinary examination hinges on the quality of information the owner supplies. Accurate preparation reduces diagnostic delays and helps the clinician focus on relevant cardiac signs.

Collect the dog’s medical records, including previous heart auscultations, imaging reports, and any medication lists. Bring a written timeline of observable symptoms such as coughing, reduced exercise tolerance, fainting episodes, or abnormal breathing patterns. Note the frequency, duration, and circumstances of each event.

Gather objective data that can be measured at home:

Resting heart rate (beats per minute) taken after the dog has been calm for at least five minutes.
Respiratory rate at rest, counted over a full minute.
Weight and body condition score.
Blood pressure, if a home monitor is available.

Prepare the environment for the visit. Ensure the dog is leashed or contained safely to prevent stress‑induced tachycardia before the exam. Avoid feeding a large meal within two hours of the appointment, as digestion can affect heart rate and auscultation clarity.

When arriving at the clinic, present the compiled notes and any home‑recorded charts. Answer the veterinarian’s questions succinctly, referencing the documented timeline and measurements. If the dog is on cardiac medication, disclose the exact dosage, timing, and any observed side effects.

Finally, request a clear outline of the diagnostic plan, including which tests (e.g., echocardiography, electrocardiogram, thoracic radiographs) will be performed and the rationale for each. Confirm follow‑up instructions before leaving the clinic. This systematic approach equips the veterinarian to identify and address canine heart problems efficiently.

Diagnosing Heart Problems

Veterinary Examination

Auscultation (Listening to the Heart)

Auscultation is the primary clinical method for detecting cardiac abnormalities in dogs. The veterinarian places a stethoscope on the thoracic wall, typically at the left 5th-6th intercostal space, to capture the heart’s acoustic activity. Sound quality, rhythm, and timing reveal the presence of disease.

Key auscultatory findings include:

Murmurs - turbulent flow producing a swishing or blowing sound; graded I-VI based on intensity.
Arrhythmias - irregular intervals between beats, premature beats, or pauses.
Gallop sounds - additional S3 or S4 waves indicating ventricular overload.
Splinter or click sounds - associated with valve degeneration or stenosis.

Interpretation requires comparison of the first (S1) and second (S2) heart sounds. A diminished S1 may suggest atrioventricular valve disease, while a loud S2 can indicate pulmonary hypertension. The timing of murmurs (systolic, diastolic, or continuous) narrows the differential diagnosis.

Effective auscultation depends on proper technique: a quiet environment, appropriate stethoscope diaphragm, and systematic scanning from the base to the apex. Repeating the examination over several visits confirms the persistence or progression of abnormalities. When abnormal sounds are identified, further diagnostics such as echocardiography, electrocardiography, or blood pressure measurement should follow to define the underlying pathology and guide treatment.

Palpation

As a veterinary cardiologist, I rely on palpation to assess canine cardiac health quickly and without equipment. The technique focuses on the precordial region-just behind the left forelimb-and the thoracic wall where the heart’s apex can be felt.

When performing palpation, place the pads of your index and middle fingers lightly on the left thorax. Apply enough pressure to detect motion without compressing the underlying structures. Observe the following signs:

Thrum or thrill: A palpable vibration indicates turbulent blood flow, often associated with valvular insufficiency or stenosis.
Irregular impulse: Variability in the rhythm or strength of the cardiac impulse suggests arrhythmia or myocardial disease.
Enlarged point of maximal impulse (PMI): A displaced or broadened PMI may reflect cardiomegaly due to volume overload or dilated cardiomyopathy.
Muffled or absent impulse: Diminished tactile sensation can signal pericardial effusion or severe myocardial thinning.

Timing the examination with the respiratory cycle improves accuracy; the impulse is most pronounced during expiration when intrathoracic pressure is lower. Compare the left‑side findings with the right side to identify asymmetry, which may indicate regional pathology.

If any of these abnormalities are detected, immediate further evaluation-such as auscultation, radiography, or echocardiography-is warranted to confirm the underlying condition and guide treatment. Palpation alone cannot replace diagnostic imaging but provides a rapid, bedside indicator of cardiac compromise in dogs.

Diagnostic Tests

1. Blood Tests

Blood work is a primary diagnostic tool when evaluating a dog for possible cardiac disease. Certain analytes directly reflect myocardial stress, while others reveal systemic conditions that can exacerbate heart dysfunction. Interpreting these values alongside clinical signs provides a clearer picture of the animal’s cardiovascular status.

Key laboratory parameters include:

Cardiac troponin I (cTnI): Elevated levels indicate myocardial cell injury and are strongly associated with acute and chronic heart disease.
N‑terminal pro‑BNP (NT‑proBNP): High concentrations suggest ventricular stretch and are useful for distinguishing cardiac from non‑cardiac causes of respiratory distress.
Creatine kinase‑MB (CK‑MB): Increases point to muscle damage, including cardiac muscle, though less specific than cTnI.
Electrolytes (potassium, sodium, calcium): Imbalances can precipitate arrhythmias and affect contractility; monitoring is essential for dogs with suspected heart failure.
Renal and hepatic panels: Kidney and liver dysfunction often accompany advanced cardiac disease; elevated BUN, creatinine, or liver enzymes may indicate secondary organ involvement.

When blood test results fall outside reference ranges, they should be correlated with physical examination findings, imaging studies, and the dog’s history. Consistent abnormalities across multiple cardiac markers strengthen the suspicion of heart pathology and guide further diagnostic steps such as echocardiography or electrocardiography.

2. Urinalysis

As a veterinary cardiology specialist, I consider urinalysis a valuable component of the cardiac assessment in dogs. The test provides indirect evidence of heart dysfunction through renal changes that accompany reduced cardiac output.

Key urinary indicators linked to cardiac disease include:

Protein concentration - Elevated protein levels, especially when the urine protein‑to‑creatinine (UPC) ratio exceeds 0.5, suggest glomerular leakage often secondary to chronic low‑output states.
Specific gravity - Low specific gravity (≤1.015) may reflect impaired concentrating ability caused by diminished renal perfusion.
Hematuria - Microscopic blood can result from hypertension associated with cardiac insufficiency.
Casts and cells - Presence of granular or hyaline casts, and increased epithelial cells, points to tubular stress that frequently accompanies systemic hypoperfusion.
pH and electrolytes - Slightly acidic urine and altered electrolyte excretion may accompany neurohormonal activation in heart disease.

Interpretation requires correlation with clinical signs and other diagnostics. A single abnormal result does not confirm cardiac pathology, but a pattern of proteinuria, dilute urine, and microscopic hematuria in a dog with exercise intolerance, coughing, or arrhythmia strengthens the suspicion of heart involvement. Regular urinalysis, combined with echocardiography and thoracic radiographs, enhances early detection and monitoring of canine cardiac disorders.

3. Chest X-rays

Chest radiography remains a cornerstone in evaluating canine cardiac disease. The technique provides a rapid, non‑invasive view of thoracic structures, allowing clinicians to identify patterns that suggest myocardial dysfunction, pericardial effusion, or vascular abnormalities.

Key radiographic indicators of cardiac compromise include:

Enlarged cardiac silhouette: a vertebral heart score (VHS) exceeding 10.5 V in most breeds, or a cardiothoracic ratio greater than 0.55 on a ventrodorsal view, signals cardiomegaly.
Pulmonary venous congestion: increased opacity in the caudal lung fields, often appearing as a “butterfly” pattern, reflects elevated left atrial pressure.
Pleural or pericardial effusion: fluid lines that are horizontal, well‑defined, and conform to the thoracic cavity suggest accumulation of fluid secondary to heart failure.
Pulmonary edema: diffuse, fluffy interstitial markings with superimposed alveolar patterns indicate fluid leakage into the lung parenchyma.
Pulmonary artery enlargement: a diameter exceeding 1.5 times the adjacent bronchus indicates pulmonary hypertension, frequently associated with right‑sided heart disease.

Interpretation requires comparison with breed‑specific normal ranges and correlation with clinical signs such as cough, exercise intolerance, or syncope. When radiographic findings raise suspicion of cardiac pathology, further diagnostics-echocardiography, electrocardiography, or blood biomarkers-should be pursued to confirm the diagnosis and guide treatment.

4. Electrocardiogram (ECG)

Electrocardiography provides a direct, non‑invasive record of the electrical activity generated by the canine myocardium. The trace, displayed as a series of P waves, QRS complexes, and T waves, reflects atrial depolarization, ventricular depolarization, and ventricular repolarization respectively. Deviations from normal morphology and timing reveal arrhythmias, conduction blocks, and chamber enlargement, all of which may indicate underlying cardiac disease.

When performing an ECG on a dog, follow these steps:

Place the animal in a calm, restrained position on a non‑conductive surface; lateral recumbency is preferred for consistency.
Attach disposable electrodes to the right forelimb (RA), left forelimb (LA), right hindlimb (RL), and left hindlimb (LL). Ensure adequate skin preparation to reduce impedance.
Set the machine to a paper speed of 25 mm s⁻¹ and a calibration of 10 mm = 1 mV.
Record a minimum of three consecutive cycles to capture rhythm stability.
Review the tracing for rate (beats per minute), regularity, and wave morphology.

Key ECG indicators of cardiac compromise include:

Sinus tachycardia or bradycardia - rates outside the normal range (60-140 bpm, depending on size and breed) suggest autonomic imbalance or primary pacemaker dysfunction.
Atrial premature complexes (APCs) - isolated early P waves followed by normal QRS complexes, often herald atrial enlargement or irritability.
Ventricular premature complexes (VPCs) - widened QRS complexes occurring prematurely; frequent VPCs can precede ventricular tachyarrhythmias.
Bundle branch blocks - prolonged QRS duration with characteristic morphology, indicating impaired ventricular conduction.
Elevated or depressed ST segments - may reflect myocardial ischemia, electrolyte disturbances, or drug effects.
Altered P‑R interval - prolonged intervals suggest atrioventricular nodal disease; shortened intervals may accompany accessory pathways.

Interpretation requires comparison with breed‑specific reference values, as normal amplitudes and intervals vary with body size. Confirmatory diagnostics, such as echocardiography or thoracic radiography, should accompany ECG findings when structural disease is suspected. Regular ECG monitoring aids in assessing disease progression and therapeutic response, making it an essential tool for veterinary cardiologists assessing canine heart health.

5. Echocardiogram (Ultrasound of the Heart)

An echocardiogram, also known as cardiac ultrasound, provides real‑time images of the canine heart’s chambers, valves, and blood flow. The procedure uses high‑frequency sound waves transmitted through a transducer placed on the thorax, generating cross‑sectional views that allow precise measurement of wall thickness, chamber dimensions, and contractile function. Because the technique is non‑invasive and does not require sedation in most healthy dogs, it can be repeated to monitor disease progression or therapeutic response.

Key diagnostic information obtained from an echocardiogram includes:

Left ventricular wall thickness and internal diameter, indicating hypertrophy or dilation.
Fractional shortening and ejection fraction, quantifying systolic performance.
Valve morphology and motion, revealing regurgitation, stenosis, or prolapse.
Doppler assessment of blood flow velocities across valves and within the outflow tracts, detecting turbulent flow or pressure gradients.
Presence of pericardial effusion or abnormal septal motion, suggesting secondary complications.

Interpretation of these parameters by a veterinary cardiologist confirms or rules out conditions such as dilated cardiomyopathy, subaortic stenosis, mitral valve disease, and congenital defects. Accurate measurement and comparison with breed‑specific reference ranges are essential for reliable conclusions.

6. Blood Pressure Measurement

Accurate assessment of arterial pressure is a cornerstone of canine cardiac evaluation. Elevated systolic values often precede overt murmurs, while low readings may signal pump failure or systemic vasodilation. Reliable data require consistent technique and appropriate equipment.

Common devices for veterinary use include:

Doppler ultrasonography: a probe placed over the brachial or coccygeal artery detects blood flow, allowing calculation of systolic pressure through a cuff‑inflation method.
Oscillometric monitors: cuffs applied to the same sites measure systolic, diastolic, and mean pressures automatically.

Procedure for reliable measurement:

Allow the dog to rest for at least five minutes in a quiet environment.
Choose a cuff size that encircles 40 % of limb circumference; an ill‑fitting cuff yields inaccurate values.
Position the cuff proximal to the artery, ensuring no hair or debris obstructs contact.
Inflate the cuff to a pressure 20 mm Hg above the expected systolic level, then deflate slowly (2-3 mm Hg per second) while observing the Doppler sound or oscillometric display.
Record the first audible pulse (Doppler) or the displayed systolic peak (oscillometric). Repeat the measurement three times, spacing each reading by one minute, and calculate the average.

Interpretation guidelines for adult dogs:

Normal systolic pressure: 110-150 mm Hg.
Hypertension: sustained systolic >160 mm Hg; severe hypertension >180 mm Hg.
Hypotension: systolic <90 mm Hg, often associated with advanced heart disease or shock.

Factors that may skew results include anxiety, recent exercise, temperature extremes, and improper cuff placement. Documenting trends over multiple visits provides a clearer picture of cardiovascular status than isolated readings. Regular blood pressure monitoring, combined with auscultation and imaging, enhances early detection of cardiac dysfunction in dogs.

Management and Treatment

Medical Management

When a canine patient shows signs suggestive of cardiac disease, the veterinarian must move quickly from suspicion to a structured therapeutic plan. The following steps outline evidence‑based medical management for dogs with confirmed or highly suspected heart problems.

Confirm diagnosis with diagnostic tools: thoracic radiographs to assess cardiac silhouette, electrocardiography for rhythm evaluation, and echocardiography to measure chamber size, wall thickness, and valve function. Blood tests should include complete blood count, serum biochemistry, and cardiac biomarkers such as NT‑proBNP or troponin I.
Classify the disease stage using accepted criteria (e.g., ACVIM consensus). Staging determines the intensity of intervention and informs prognosis.
Initiate pharmacologic therapy tailored to the underlying pathology:
- Positive inotropes (e.g., pimobendan) for systolic dysfunction.
- Afterload reducers (e.g., ACE inhibitors, benazepril) to decrease cardiac workload.
- Diuretics (e.g., furosemide) for pulmonary edema or systemic congestion.
- Anti‑arrhythmic agents (e.g., sotalol, mexiletine) when rhythm disturbances are documented.
- Antithrombotic drugs (e.g., clopidogrel) in cases with high risk of thromboembolism.
Adjust dosages based on serial assessments of blood pressure, renal function, and electrolyte balance. Regular re‑evaluation prevents adverse effects and ensures therapeutic efficacy.
Implement lifestyle modifications: weight control, reduced sodium intake, moderate exercise according to tolerance, and avoidance of stressors that could precipitate decompensation.
Schedule follow‑up examinations at intervals dictated by disease stage: every 1-3 months for advanced heart failure, every 6-12 months for mild or stable conditions. Each visit should repeat cardiac imaging and biomarker testing to track progression.
Educate owners on recognizing early signs of deterioration, such as increased respiratory effort, coughing, lethargy, or syncope, and provide clear instructions for emergency medication administration.

By adhering to this systematic approach, clinicians can stabilize cardiac function, alleviate clinical signs, and extend the quality of life for dogs suffering from heart disease.

Lifestyle Adjustments

Veterinary cardiology specialists advise that modifying a dog’s daily routine can reveal early signs of cardiac dysfunction and reduce disease progression.

A controlled diet limits excess sodium and calories, stabilizing blood pressure and preventing obesity‑related strain on the heart. Offer high‑quality protein, omega‑3 fatty acids, and fiber while measuring portions to maintain an ideal body condition score.

Regular, moderate exercise improves myocardial efficiency and helps owners notice abnormal fatigue or respiratory distress. Begin with short walks, gradually increasing duration; record the distance and the dog’s breathing pattern. Sudden intolerance to previously manageable activity often signals compromised cardiac output.

Weight management is essential. Monitor weight weekly; a gain of more than 1-2 % of body mass within a month warrants dietary reassessment. Overweight dogs exhibit elevated heart rates and reduced stamina, masking subtle cardiac symptoms.

Environmental stressors should be minimized. Keep temperature extremes out of the home, provide a quiet resting area, and avoid excessive excitement before meals. Stress amplifies heart rate and can obscure baseline auscultation findings.

Routine health checks create a reliable baseline for comparison. Record resting heart rate, respiratory rate, and mucous membrane color each morning. Use a digital timer to measure the time required for the dog to complete a predefined obstacle course; increased completion time may indicate declining cardiac performance.

Implementing these lifestyle adjustments equips owners with objective data, facilitates early detection of heart problems, and supports veterinary intervention.

Prognosis and Quality of Life

When a canine patient presents with signs that may indicate cardiac disease, clinicians must evaluate two interrelated outcomes: the likely disease course and the animal’s day‑to‑day wellbeing.

Prognosis hinges on the underlying condition, stage at diagnosis, and response to therapy. Congenital defects diagnosed early often have a favorable outlook if surgical correction is possible. Acquired diseases such as dilated cardiomyopathy or chronic valvular insufficiency carry a more guarded prognosis, especially when echocardiographic measurements exceed established severity thresholds. Survival statistics improve markedly after initiating ACE inhibitors, diuretics, and pimobendan, provided that dosage adjustments are made promptly in response to repeat examinations. Regular re‑evaluation of cardiac dimensions, fractional shortening, and heart rate variability offers objective data to refine life‑expectancy estimates.

Quality of life assessment requires systematic observation of functional capacity and comfort. Key indicators include:

Ability to rise and walk without excessive fatigue or respiratory distress
Appetite stability and maintenance of normal body condition
Absence of persistent cough, labored breathing, or syncope
Frequency and severity of episodes of edema or ascites
Owner‑reported enjoyment of favorite activities (e.g., play, walks)

Each factor should be scored on a standardized scale (for example, 0 = absent, 1 = mild, 2 = moderate, 3 = severe). Summed scores guide therapeutic adjustments, such as increasing diuretic dosage, adding anti‑arrhythmic agents, or considering palliative measures when discomfort outweighs clinical benefit.

When prognosis is poor but quality of life remains acceptable, the decision to continue aggressive treatment versus transition to hospice care must be individualized. Ethical considerations involve balancing the animal’s capacity for pain‑free activity against the burden of intensive medication regimens and frequent veterinary visits. Transparent communication with owners, supported by objective data from physical exams, imaging, and laboratory tests, ensures that choices align with the dog’s best interests and the owner’s expectations.