Overview
This lecture covered recent updates in feline cardiology therapeutics and practical approaches to anesthesia in dogs and cats with heart disease, followed by a brief overview of a new diet for canine cardiac patients.
Updates in Feline Cardiovascular Therapeutics
- Rapamycin (Rapa): Investigated for subclinical hypertrophic cardiomyopathy (HCM) in cats; shown to slow progression of ventricular hypertrophy over 6 months versus placebo.
- Adverse effects occurred in 1/6 of treated cats, including episodes of congestive heart failure and one case of diabetic ketoacidosis.
- Long-term safety and specific cat selection for rapamycin treatment remain unclear; not yet recommended for routine use.
- Rivaroxaban: A novel anticoagulant investigated for prevention of saddle thrombi (aortic thromboembolism) in cats.
- No drug has yet been proven to prevent the first blood clot in cats with HCM, but dual therapy (clopidogrel + rivaroxaban) showed promising results in high-risk cats.
- Selection of antithrombotic therapy is individualized based on left atrial enlargement, risk assessment, and owner preference/compliance.
- Pimobendan: Initially showed promise in retrospective studies for HCM with heart failure but a prospective, double-blinded trial found no significant long-term benefit over furosemide alone.
- Pimobendan may be considered only for cats with systolic dysfunction or rare cases of dilated cardiomyopathy, not for routine HCM cases.
Practical Anesthesia in Cardiac Patients
- Assess if the patient’s heart disease is compensated (asymptomatic) or decompensated (in heart failure) prior to anesthesia.
- Use patient signalment, history, physical exam, and basic diagnostics to differentiate likely diastolic (cats/HCM) vs. systolic (dogs/DCM or advanced mitral disease) dysfunction.
- Compensated cardiac patients can generally tolerate anesthesia with adapted protocols and careful monitoring.
- Pre-anesthetic evaluation includes chest X-rays, basic blood work, and point-of-care ultrasound (POCUS) if possible.
- Use cautious premedication (low-dose dexmedetomidine, benzodiazepines, and opioids); avoid routine atropine/glycopyrrolate unless bradycardic and hypotensive.
- Propofol and alfaxalone are suitable induction agents if titrated carefully.
- Continue cardiac medications on the morning of surgery but skip ACE inhibitors to avoid anesthesia-induced hypotension.
- Preoxygenate high-risk patients for at least 3 minutes pre-induction.
- Use reduced fluid maintenance rates and consider low-sodium isotonic fluids.
Monitoring, Complications, and Troubleshooting
- Closely monitor pulse, pulse oximetry, ECG, and blood pressure; even minimal monitoring reduces anesthetic risk.
- Common intraoperative issues: manage hypotension by reducing inhalant anesthetic, providing fluids carefully, and using vasopressors if needed.
- Recognize and manage arrhythmias (e.g., bradycardia, PVCs); treat underlying causes first.
- ECG artifacts are common; verify before interpreting.
Purina CardioCare Diet for Dogs
- CardioCare is a new diet for dogs with myxomatous mitral valve disease (MMVD), containing medium-chain triglycerides, amino acids, fish oils, vitamin E, and magnesium for improved cardiac metabolism and reduced inflammation.
- Demonstrated to slow left atrial enlargement and mitral regurgitation progression in preclinical (Stage B) MMVD dogs.
- Suitable for early intervention (Stage B1) and nutritionally appropriate for adult dogs, even with other cardiac conditions.
- For dogs with co-morbidities (e.g., kidney disease), consult with a veterinary nutritionist.
Key Terms & Definitions
- HCM (Hypertrophic Cardiomyopathy) — A disease causing thickening of the heart's left ventricle, common in cats.
- Rapamycin — An immunosuppressive and antifibrotic drug investigated for slowing HCM progression.
- Rivaroxaban — An oral anticoagulant targeting factor Xa to prevent blood clots.
- Clopidogrel (Plavix) — An antiplatelet drug used to reduce risk of thromboembolism.
- Pimobendan — A positive inotrope and vasodilator used in heart failure.
- Compensated Heart Disease — Cardiac disease with no clinical signs of heart failure.
- Decompensated Heart Disease — Cardiac disease with clinical signs of heart failure (e.g., pulmonary edema).
- MMVD — Myxomatous Mitral Valve Disease, a common degenerative heart disease in dogs.
Action Items / Next Steps
- Review current evidence and exercise caution before prescribing new cardiac medications (rapamycin, rivaroxaban, pimobendan) in feline practice.
- For anesthesia cases, implement thorough pre-evaluation, careful drug selection, and appropriate monitoring for heart patients.
- For canine patients with preclinical MMVD, consider discussing CardioCare diet as early nutritional intervention.
- Register for upcoming CE sessions on anesthesia and dentistry if interested.