Veterinary CPD webinar – Feline Cardiology Basics: Key Clinical Takeaways for Veterinary Students

1. Screening for Heart Disease in Cats

Unlike dogs, cats can have significant heart disease without a murmur.

• Gallop rhythms are more concerning than soft murmurs.
• Murmurs may be dynamic — they can appear or disappear depending on stress level, anemia, or excitement.
• Clinical signs are often nonspecific: lethargy, weight loss, tachypnea, hindlimb weakness, or collapse.

Pro tip for owners: Purring can make cats appear tachypneic. Teach owners to count resting respiratory rates when the cat is calm and not purring.

Screening Options

• Plan A (Gold standard): Echocardiogram, blood pressure, T4, ± thoracic radiographs.
• Plan B: Chest radiographs, NT-proBNP, blood pressure, T4.
• Plan C: NT-proBNP, T4, blood pressure, and home monitoring of resting respiratory rate.

⚠️ Interpret NT-proBNP carefully: it’s cleared by the kidneys, so cats with kidney disease may have falsely elevated results.

Also note: cats often have dynamic right ventricular outflow tract obstructions — benign causes of soft, variable murmurs that don’t always indicate structural heart disease.

2. Common Acquired Cardiac Diseases

Hypertrophic Cardiomyopathy (HCM)

• The most common heart disease in cats.
• Genetic predispositions: Maine Coons and Sphynx (tests available but not fully predictive).
• Secondary causes: Hypertension, hyperthyroidism, hypovolemia (“pseudo-hypertrophy”), acromegaly.
• Echocardiographic findings: Concentric hypertrophy ± left atrial enlargement.
• Dynamic obstruction (HOCM): Caused by systolic anterior motion (SAM) of the mitral valve → murmur.

Treatment notes:

• For asymptomatic cats, clopidogrel is more effective than aspirin in reducing thromboembolic risk.
• Limited evidence supports ACE inhibitors, pimobendan, or spironolactone use in cats.

Transient Myocardial Thickening

• Seen in young cats after stress or systemic illness (e.g., viral infection, trauma).
• Echo findings can mimic HCM initially but normalize with recovery.
• Serial echocardiography helps differentiate this from true HCM.

Restrictive Cardiomyopathy (RCM)

• Characterized by biatrial enlargement with normal or thin walls and poor relaxation.
• Can resemble advanced HCM or DCM.
• Prognosis depends on degree of diastolic dysfunction.

Dilated Cardiomyopathy (DCM)

• Rare today but historically linked to taurine deficiency.
• May occur secondary to systemic illness (e.g., sepsis).
• Check for retinal degeneration in suspected taurine-deficient cats.

3. Congenital Heart Diseases

Ventricular Septal Defect (VSD)

• The most common congenital cardiac defect in cats.
• Produces a loud systolic murmur, often right parasternal.
• Prognosis is variable: some cats remain stable, while others develop CHF or pulmonary hypertension.
• Goal: minimize shunting and manage symptoms; sometimes beta-blockers like propranolol are used.

Patent Ductus Arteriosus (PDA)

• Presents with a loud continuous murmur (though continuous component may be hard to detect).
• No sex predilection in cats.
• If flow is not reversed, surgical ligation offers an excellent prognosis.

⚡ 4. Arrhythmias in Cats

• Arrhythmias are uncommon unless secondary to another condition (e.g., HCM, hyperthyroidism).
• Hyperthyroid cats may have frequent VPCs or tachyarrhythmias — treat the underlying endocrine disease first.
• Avoid lidocaine: cats are highly sensitive, with risk of CNS and cardiovascular depression.

Common patterns to recognize:

• Atrial fibrillation: Irregularly irregular rhythm, no P waves.
• Sinus arrhythmia or purring artifact: Regular rhythm or vibration pattern that mimics fibrillation.
• Hyperkalemia: Bradycardia, absent P waves, tall T waves — often seen in blocked cats.

💔 5. Common Complications of Feline Heart Disease

• Congestive Heart Failure (CHF): May cause pleural effusion, pulmonary edema, or pericardial effusion. Cats often “choose” one manifestation per episode.
• Atrial Thromboembolism (ATE): Painful, often presents as acute hindlimb paralysis (the “five P’s”: pain, pallor, pulselessness, paralysis, poikilothermy).
• Sudden death: Possible in severe cardiomyopathy.
• Pericardial effusion: More commonly due to CHF than neoplasia in cats.

Emergency management of CHF:

• Furosemide (1 mg/kg IV/IM), oxygen, minimal stress handling.
• Clopidogrel for clot prevention once stable.
• Pimobendan or ACE inhibitors may be added later depending on echo findings.

ATE management:

• Aggressive pain control (methadone, fentanyl CRI — not buprenorphine).
• Supportive care ± concurrent CHF management.
• Monitor for reperfusion injury and hyperkalemia during recovery.
• Physiotherapy is often required; prognosis is guarded but can improve over weeks.

Final Thoughts

Cats are unpredictable when it comes to cardiac disease — clinical signs are subtle, murmurs are unreliable, and progression varies widely.
Dr. Katrin emphasized a few key reminders for students:

• Don’t rely solely on auscultation.
• Always assess respiratory effort and rate.
• Serial monitoring and echocardiography are invaluable.
• Be cautious interpreting BNP in renal cats.
• Above all, tailor your diagnostic and therapeutic approach to each individual cat and its owner’s resources.