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Questions and Answers
Which of the following breeds is predisposed to dilated cardiomyopathy?
Which of the following breeds is predisposed to dilated cardiomyopathy?
What clinical sign is NOT typically seen in a dog with congestive heart failure?
What clinical sign is NOT typically seen in a dog with congestive heart failure?
Which of the following is a common echocardiographic finding in dilated cardiomyopathy?
Which of the following is a common echocardiographic finding in dilated cardiomyopathy?
What is the most likely cause of Samantha's arrhythmia, given the provided information?
What is the most likely cause of Samantha's arrhythmia, given the provided information?
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What radiographic finding is commonly seen in dogs with congestive heart failure?
What radiographic finding is commonly seen in dogs with congestive heart failure?
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Which of the following medications when administered intravenously can be used to increase contractility in a dog with acute congestive heart failure?
Which of the following medications when administered intravenously can be used to increase contractility in a dog with acute congestive heart failure?
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Which of the following is a loop diuretic commonly used in the treatment of congestive heart failure?
Which of the following is a loop diuretic commonly used in the treatment of congestive heart failure?
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What is the primary goal of therapy in a dog with atrial fibrillation (AF)?
What is the primary goal of therapy in a dog with atrial fibrillation (AF)?
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Which of the following medications is considered the first-line treatment for ventricular tachycardia in dogs?
Which of the following medications is considered the first-line treatment for ventricular tachycardia in dogs?
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What is the typical dosage of lidocaine given as an IV bolus in dogs with ventricular tachycardia?
What is the typical dosage of lidocaine given as an IV bolus in dogs with ventricular tachycardia?
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What is the typical range for a continuous rate infusion (CRI) of lidocaine in dogs with ventricular tachycardia?
What is the typical range for a continuous rate infusion (CRI) of lidocaine in dogs with ventricular tachycardia?
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Which of the following is a potential side effect of lidocaine toxicity in dogs?
Which of the following is a potential side effect of lidocaine toxicity in dogs?
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Which of the following conditions is characterized by fibrofatty replacement and loss of normal myocardial tissue?
Which of the following conditions is characterized by fibrofatty replacement and loss of normal myocardial tissue?
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Which of the following breeds is specifically known to be affected by taurine deficiency leading to dilated cardiomyopathy (DCM)?
Which of the following breeds is specifically known to be affected by taurine deficiency leading to dilated cardiomyopathy (DCM)?
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In a 24-hour Holter monitor, which findings are considered diagnostic for arrhythmogenic right ventricular cardiomyopathy (ARVC)?
In a 24-hour Holter monitor, which findings are considered diagnostic for arrhythmogenic right ventricular cardiomyopathy (ARVC)?
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Which of the following is NOT a clinical finding associated with compensated dilated cardiomyopathy (DCM)?
Which of the following is NOT a clinical finding associated with compensated dilated cardiomyopathy (DCM)?
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What is the primary pathophysiological mechanism leading to pulmonary edema in DCM?
What is the primary pathophysiological mechanism leading to pulmonary edema in DCM?
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Which of the following is NOT a characteristic of dilated cardiomyopathy (DCM) pathology?
Which of the following is NOT a characteristic of dilated cardiomyopathy (DCM) pathology?
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Which of these clinical signs is most suggestive of right-sided congestive heart failure (CHF) in a patient with DCM?
Which of these clinical signs is most suggestive of right-sided congestive heart failure (CHF) in a patient with DCM?
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What is the primary mechanism responsible for the development of functional (secondary) valvular regurgitation in DCM?
What is the primary mechanism responsible for the development of functional (secondary) valvular regurgitation in DCM?
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Which of the following radiographic findings is NOT associated with right-sided heart failure (RCHF)?
Which of the following radiographic findings is NOT associated with right-sided heart failure (RCHF)?
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What is the typical echocardiographic finding in a dog with dilated cardiomyopathy (DCM) that is associated with systolic mitral regurgitation (MR)?
What is the typical echocardiographic finding in a dog with dilated cardiomyopathy (DCM) that is associated with systolic mitral regurgitation (MR)?
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What is the common electrocardiographic finding in a dog diagnosed with DCM?
What is the common electrocardiographic finding in a dog diagnosed with DCM?
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Which of the following breeds is NOT commonly predisposed to DCM?
Which of the following breeds is NOT commonly predisposed to DCM?
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What is the difference in echocardiographic findings between a dog with Degenerative Valve disease and a dog with DCM?
What is the difference in echocardiographic findings between a dog with Degenerative Valve disease and a dog with DCM?
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Flashcards
Dilated Cardiomyopathy
Dilated Cardiomyopathy
A heart condition characterized by the dilation of the heart's chambers, leading to decreased contractility and heart failure.
Congestive Heart Failure (CHF)
Congestive Heart Failure (CHF)
A clinical syndrome where the heart's ability to pump blood is inadequate to meet the body's needs, often due to cardiomyopathy.
Clinical Signs of CHF
Clinical Signs of CHF
Signs include coughing, lethargy, exercise intolerance, and difficulty breathing in affected dogs.
Echocardiographic Findings
Echocardiographic Findings
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Differential Diagnoses for Left Heart Failure
Differential Diagnoses for Left Heart Failure
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Dilated Cardiomyopathy (DCM)
Dilated Cardiomyopathy (DCM)
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Systolic Dysfunction
Systolic Dysfunction
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Pulmonary Edema
Pulmonary Edema
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Clinical Signs of DCM
Clinical Signs of DCM
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Compensated vs Decompensated CHF
Compensated vs Decompensated CHF
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Cardiomegaly
Cardiomegaly
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Left Atrial Enlargement
Left Atrial Enlargement
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Atrial Fibrillation
Atrial Fibrillation
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Acute Therapy - CHF
Acute Therapy - CHF
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Furosemide
Furosemide
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Pimobendan
Pimobendan
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Lidocaine in Ventricular Tachycardia
Lidocaine in Ventricular Tachycardia
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Max Lidocaine Dosage
Max Lidocaine Dosage
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Atrial Fibrillation Therapy
Atrial Fibrillation Therapy
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Boxer Cardiomyopathy
Boxer Cardiomyopathy
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Holter Monitor
Holter Monitor
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Chronic CHF therapy
Chronic CHF therapy
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Taurine and DCM
Taurine and DCM
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Study Notes
Canine Cardiomyopathy
- Myocardial disease in dogs, particularly dilated cardiomyopathy (DCM)
- Learning objectives include describing DCM pathophysiology, diagnostic testing, etiologies, clinical signs, treatment for congestive heart failure (CHF), and breed predisposition.
- Samantha, a 6-year-old Doberman Pinscher, presented with a 2-week history of progressive coughing, lethargy, and exercise intolerance, along with 24-hour history of difficulty breathing, inappetence, and syncope.
Samantha - Physical Exam
- Respiratory rate (RR): 70 breaths/minute
- Heart rate (HR): 300 beats per minute
- Temperature: 99.5°F
- Physical exam findings include: pale pink, dry mucous membranes; distended jugular veins; bilateral pulmonary crackles; a Grade III/VI left apical systolic murmur; and weak femoral pulses.
Case Study Questions
- What causes Samantha's arrhythmia? Is it an emergency?
- What are the signs of congestive heart failure?
- What are the differential diagnoses for left-sided heart failure in dogs?
- What are the radiographic and echocardiographic abnormalities?
Canine Cardiomyopathy
- Primary:
- Dilated cardiomyopathy (DCM): A disorder of the cardiac muscle, characterized by heart enlargement
- Arrhythmogenic right ventricular cardiomyopathy (ARVC): another primary cardiomyopathy affecting the right ventricle
- Secondary:
- Nutritional deficiencies
- Infectious myocarditis
- Drug-induced/toxic cardiomyopathies
- Tachycardia-induced cardiomyopathy
- Differential diagnoses for left heart failure:
- Likely a primary cardiomyopathy like DCM in Samantha
- Additional considerations: Congenital heart defects
Dilated Cardiomyopathy (DCM) - Pathology
- Four-chamber enlargement, with the left side typically more affected than the right.
- Walls are thinned to normal.
- Valves are normal.
- Myocardial fibrosis is present.
Pathophysiology
- Systolic dysfunction leads to decreased stroke volume.
- Activation of the renin-angiotensin-aldosterone system (RAAS) due to hypotension.
- Secondary (functional) valvular regurgitation due to annular stretch.
- Cardiac chamber dilation (profound left atrial and ventricular dilation).
- Increased atrial pressure leading to pulmonary edema/left-sided congestive heart failure (or ascites if the right side is involved as well).
- Arrhythmias can be due to atrial or ventricular ischemia.
Clinical Findings - DCM
- Compensated:
- Murmur (systolic, apical, left or right).
- Gallop (S3) sound due to ventricular dilation.
- Weak femoral pulses
- Arrhythmias with pulse deficits
- Decompensated (CHF):
- Tachypnea
- Cough
- Tachycardia
- Crackles
- Right-sided CHF signs include ascites, distended jugular veins, muffled heart sounds, and tachycardia
Radiographic Findings
- Generalized cardiomegaly
- Prominent left atrial and left ventricular enlargement.
- Left-sided congestive heart failure (L CHF):
- Distended pulmonary veins
- Pulmonary interstitial/alveolar infiltrates
- Right-sided congestive heart failure (R CHF):
- Distended caudal vena cava
- Pleural effusion
- Ascites
Electrocardiography
- Tall R waves indicate left ventricular enlargement.
- Tall or wide P waves may suggest right or left atrial enlargement.
- Atrial fibrillation is common.
- Ventricular arrhythmias (VPCs or VT) may occur.
- Tachycardias can contribute to CHF.
Breed Predisposition - DCM
- More common in large breed dogs:
- Doberman Pinscher
- Great Dane
- Irish Wolfhound
- American Cocker Spaniel
- Boxer
- Juvenile Portuguese Water Dog
Echocardiography
- Chamber dilation
- Systolic dysfunction
- Systolic mitral regurgitation (MR)
- Typically a central jet.
- Left atrial (LA) enlargement.
- Left ventricular (LV) eccentric hypertrophy
- Measure fractional shortening (FS).
- Decreased (typically less than 25%).
Degenerative Valve vs. DCM
- Differentiators based on physical exam and echocardiography
Acute Therapy - Congestive Heart Failure (CHF)
- Oxygen supplementation
- Intravenous (IV) furosemide (decrease preload).
- Pimobendan (PO), dobutamine (IV) (increase contractility).
- Sedation +/-
- Afterload reducer (nitroprusside) +/-
Chronic CHF Therapy
- Furosemide (loop diuretic)
- Enalapril or benazepril (ACE inhibitor).
- Pimobendan (inodilator).
- Spironolactone (aldosterone antagonist)
Follow-up
- Recheck visit 5–7 days post initial treatment.
- Thoracic radiographs are taken.
- Renal panel is assessed.
- Blood pressure is measured.
- Electrocardiogram (ECG) might be used.
Additional Diagnostic Testing
- 24-hour ambulatory Holter monitoring
- Ambulatory event monitor
- Serum biochemistries, PCV/TS (or CBC), +/- urinalysis (U/A).
Antiarrhythmic Therapy - Ventricular Tachycardia
-
Acute Therapy:
- Lidocaine (first choice for dogs)
- IV bolus (2 mg/kg).
- Short-lived effect, follow with continuous IV infusion (CRI) (50-75 mcg/kg/min).
- Monitor serum electrolytes.
-
Other acute options
- Procainamide IV
- Magnesium sulfate or Magnesium chloride
- Esmolol
- Amiodarone
-
Chronic Therapy
- Sotalol (with caution in heart failure)
- Mexiletine
- Sotalol + Mexiletine combination
- Amiodarone
Lidocaine Toxicity
- Do not exceed 8 mg/kg IV over 30 minutes
- Gastrointestinal upset
- Tremors
- Seizures can occur.
Therapy - Atrial Fibrillation (AF)
- AF is rarely reversible; the goal is to slow the transmission of impulses to the ventricle, bringing the ventricular contraction rate to a safe range.
- Medications including diltiazem +/-digoxin.
- Beta Blocker
Therapy - Right-Sided CHF(RCHF)
Specific Cases - Dilated Cardiomyopathy (DCM)
-
Doberman Pinscher DCM
- Breed screening for occult disease (young dogs 3-4 years of age).
- 24-hour Holter monitor (and/or recheck after a period of time).
- Echocardiogram
- Genetic testing (e.g., pyruvate dehydrogenase 4 deficiency).
-
American Cocker Spaniel DCM
- Potential association with taurine deficiency (common in the late 20th century).
- Measure blood taurine levels (normal 200-350 nmol/L)
- Can result in heart failure.
- Supplementation with taurine.
Diet-Associated DCM
- Nutritionally based cardiomyopathy may occur in some dogs
- Diet changes and echo improvement (taurine supplementation) but blood tests normal in some situations.
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)
-
"Boxer Cardiomyopathy"
-
Primary disease of the heart muscle
-
Arrhythmias, syncope, sudden cardiac death
-
Inherited disease, adult onset (typically after 6 years old)
-
Forms:
- Asymptomatic ventricular arrhythmias
- Symptomatic ventricular arrhythmias (with syncope or sudden death).
- Ventricular arrhythmias with congestive heart failure
- Echocardiogram findings may be normal.
- 24-hour Holter monitor to diagnose (looking for criteria: ≥100 ventricular premature complexes/couplets in 24 hours, R-on-T phenomenon).
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Description
Test your knowledge on canine cardiology with this quiz focusing on dilated cardiomyopathy, congestive heart failure, and important treatments. Each question highlights key indicators and treatment protocols relevant to veterinary practice. Perfect for veterinary students and professionals!
