Top 10 Small Animal Cardiology Conditions: A Comprehensive NAVLE Guide (Part 3)
Introduction
In the final part of our series on small animal cardiology, we explore the most complex and critical cardiac conditions that veterinary professionals must understand for the NAVLE. This guide offers in-depth information on diagnosis, treatment, and management of these conditions in clinical practice.
8. Hypertrophic Cardiomyopathy (HCM)
Classic Case:
HCM primarily affects adult cats, with males being more predisposed, especially Maine Coons and Ragdolls. Often, there are no clinical signs until acute death occurs. Symptoms include tachypnea, dyspnea, and potential paraplegia due to thromboembolism. Murmurs and arrhythmias are usually absent.
Diagnosis:
- Thoracic Radiography: Look for cardiomegaly, dilated left atrium, pulmonary edema, and pleural effusion.
- Echocardiography (M-mode): Identifies atrial dilation, left ventricular wall thickening, papillary muscle hypertrophy, and systolic anterior motion of the mitral valve.
Treatment:
- Congestive Heart Failure (CHF): Use supplemental oxygen and loop diuretics.
- Medication: ACE inhibitors, β-blockers for left ventricular outflow obstruction.
- Thromboembolism Management: Heparin and analgesia in hospital; clopidogrel and enoxaparin at home.
Pearls:
The prognosis is poor to fair depending on the severity of the disease and response to treatment. Cats with echo contrast in the left atrium are prone to thromboembolism.
9. Top 3 Heart Block Patterns (Second-Degree, Third-Degree, Sick Sinus Syndrome)
Classic Case:
- Second-Degree Heart Block: Exercise intolerance and syncope with high-grade block.
- Third-Degree Heart Block: Syncope in dogs, rare signs in cats.
- Sick Sinus Syndrome (SSS): Severe bradycardia, exercise intolerance, and syncope, common in Miniature Schnauzers, West Highland White Terriers, and Cocker Spaniels.
Diagnosis:
- ECG: Detects P-wave abnormalities and dissociation between P-wave and QRS complex.
- Echocardiography: Evaluates structural disease and secondary heart changes.
Treatment:
- Second-Degree and Third-Degree Block: Pacemaker.
- SSS: Pacemaker and medication management for brady-tachy syndrome.
Pearls:
Treatment is necessary if bradycardia causes clinical signs. Third-degree block requires intervention due to the risk of sudden death.
10. Top 5 Congenital Conditions (PDA, Subaortic Stenosis, Pulmonic Stenosis, ASD/VSD, Tetralogy of Fallot)
Classic Case:
- PDA: More common in breeds like Poodles and German Shepherds, presenting with a continuous murmur.
- Subaortic Stenosis (SAS): Common in Golden Retrievers and Rottweilers, with a systolic murmur.
- Pulmonic Stenosis (PS): Systolic murmur, seen in Bulldogs and Labrador Retrievers.
- ASD/VSD: Varies in murmur presence, ASD may not present with murmur.
- Tetralogy of Fallot: Exercise intolerance, cyanosis, and murmurs.
Diagnosis:
- Imaging: Radiography and echocardiography to assess defects and blood flow.
- CBC: For Tetralogy of Fallot, look for polycythemia.
Treatment:
- PDA: Surgical ligation or transarterial occlusion.
- SAS: Atenolol, though surgical interventions are often unsuccessful.
- PS: Balloon valvuloplasty for severe cases.
- ASD/VSD: Treatment varies by defect size; patch repair for larger defects.
- Tetralogy of Fallot: β-blockers and phlebotomy for erythrocytosis.
Pearls:
Early detection and treatment can significantly improve prognosis for many congenital conditions. PDA repair offers a good prognosis, while severe SAS and Tetralogy of Fallot have poorer outcomes.
BONUS: Endocarditis
Classic Case:
Typically affects dogs over 4 years old with systemic illness signs, intermittent lameness, and CHF symptoms. Breed predispositions include German Shepherds and Labrador Retrievers.
Diagnosis:
- Echocardiography: Reveals thickened valves and possible masses.
- Blood and Urine Cultures: Help identify bacterial etiology.
Treatment:
- Antibiotics: Long-term, based on culture results. Use empirical broad-spectrum antibiotics initially.
- CHF Management: Oxygen therapy, furosemide, and ACE inhibitors.
Pearls:
Prognosis depends on the affected valve and promptness of treatment. Mitral valve endocarditis generally has a more favorable outcome than aortic valve involvement.