Top 5 Congenital Heart Conditions in Dogs: PDA, SAS, PS, ASD/VSD, and Tetralogy of Fallot (NAVLE Notes)
Congenital heart defects are structural abnormalities present at birth. Here’s an overview of the top five, including their typical presentations, diagnostic findings, and treatment options.
PDA in dogs/cats
Subaortic Stenosis in dogs/cats
Pulmonic Stenosis in dogs/cats
Ventricular Septal Defect in dogs/cats
Classic Cases
- Patent Ductus Arteriosus (PDA):
- Breeds: Poodles, Chihuahuas, Maltese, Bichon Frise, Pomeranians, German Shepherds, Labrador Retrievers, Newfoundlands.
- Signs: Continuous “washing machine” murmur at the left base, more common in females.
- Reverse PDA: Cyanotic caudal body mucous membranes (vulva or prepuce) with pink gingiva.
- Subaortic Stenosis (SAS):
- Breeds: Golden Retrievers, Rottweilers, Mastiffs, Newfoundlands, Boxers, German Shepherds.
- Signs: Systolic murmur at the left base, +/- weak pulses.
- Pulmonic Stenosis (PS):
- Breeds: French Bulldogs, English Bulldogs, Labrador Retrievers, Beagles, Samoyeds, Cocker Spaniels.
- Signs: Systolic murmur at the left base.
- Atrial/Ventricular Septal Defect (ASD/VSD):
- Breed for ASD: English Springer Spaniel.
- Signs: ASD often has no murmur, VSD may present with a right thoracic systolic murmur.
- Tetralogy of Fallot:
- Breeds: English Bulldogs, Samoyeds, Keeshonds, Terriers.
- Signs: Exercise intolerance, syncope, left-sided systolic murmur, differential cyanosis (more pronounced in caudal body mucous membranes).
Diagnosis
- PDA:
- Etiology: Persistent fetal ductus arteriosus, causing left-to-right shunting.
- Reverse PDA: Severe pulmonary hypertension reverses flow to right-to-left shunt, causing caudal body hypoxia.
- Radiography: Left atrial/ventricular enlargement, distinct pulmonary artery, and ascending aorta “ductus bulge.”
- Echocardiography: Continuous turbulent flow in the pulmonary artery, with ductus visible.
- SAS:
- Radiography: Prominent aortic arch bulge, left ventricular enlargement.
- Echocardiography: Turbulent flow through the aortic valve, subvalvular narrowing.
- PS:
- Radiography: Right-sided cardiomegaly, main pulmonary artery bulge.
- Echocardiography: High-velocity flow past the pulmonary valve, pulmonic valve stenosis, right ventricular hypertrophy.
- ASD/VSD:
- Radiography: ASD may show dilated pulmonary artery and right ventricular dilation; VSD shows left atrial and ventricular dilation.
- Echocardiography: Visualizes septal defects.
- Tetralogy of Fallot:
- CBC: Polycythemia due to chronic hypoxia.
- Echocardiography: Four signs — interventricular septal defect, pulmonic stenosis, right ventricular hypertrophy, overriding aorta.
Treatment
- PDA:
- Surgical Ligation: Via thoracotomy or transarterial occlusion with Amplatz® Canine Duct Occluder.
- Reverse PDA: Occlusion contraindicated; treat polycythemia with phlebotomy if necessary.
- SAS:
- Medications: Atenolol to reduce arrhythmia risk; surgeries generally ineffective.
- PS:
- Balloon Valvuloplasty: Effective in severe cases; more challenging in English Bulldogs due to concurrent artery anomalies.
- ASD/VSD:
- Small defects typically require no treatment.
- Large Defects: Patch graft repair for VSD, with amlodipine to reduce afterload.
- Tetralogy of Fallot:
- Medications: β-blockers to manage symptoms; phlebotomy for erythrocytosis. No curative surgery available.
Key Points
- Prognosis:
- PDA: Good with repair; guarded to poor if untreated.
- SAS: Mild to moderate cases may live a normal lifespan; severe cases have a poor prognosis.
- PS: Mild to moderate cases have a good prognosis; severe cases have a guarded to poor prognosis if untreated.
- ASD/VSD: Good with small defects; guarded for large defects.
- Tetralogy of Fallot: Often results in early death in hemodynamically affected animals.
NAVLE-Style Practice Questions on Congenital Heart Conditions
Question 1
A 1-year-old Chihuahua is presented with exercise intolerance and a continuous murmur at the left base. Radiographs reveal left ventricular enlargement and a ductus bulge. What is the most likely diagnosis?
- A) Subaortic stenosis
- B) Patent ductus arteriosus
- C) Pulmonic stenosis
- D) Atrial septal defect
Correct Answer: B
Explanation: PDA is characterized by a continuous “washing machine” murmur, left-sided heart changes, and a ductus bulge on radiography.
Question 2
A 3-year-old Boxer presents with a left base systolic murmur and weak pulses. Echocardiography shows high-velocity turbulent flow below the aortic valve. What is the most likely diagnosis?
- A) Pulmonic stenosis
- B) Patent ductus arteriosus
- C) Subaortic stenosis
- D) Tetralogy of Fallot
Correct Answer: C
Explanation: Subaortic stenosis commonly presents in Boxers with a left base murmur, weak pulses, and high-velocity turbulent flow in the subaortic region.
Question 3
A Samoyed is diagnosed with tetralogy of Fallot. Which of the following is not a characteristic of this condition?
- A) Pulmonic stenosis
- B) Left ventricular hypertrophy
- C) Right ventricular hypertrophy
- D) Interventricular septal defect
Correct Answer: B
Explanation: Tetralogy of Fallot includes right ventricular hypertrophy, pulmonic stenosis, an interventricular septal defect, and an overriding aorta; left ventricular hypertrophy is not a feature.
For study notes visit cracknavle.com
Transfer vhs tapes
Comment awaiting moderation.