Pre-anaesthetic risk assessment and management of dogs with myxomatous mitral valve disease: a spectrum of care narrative review.

Myxomatous mitral valve disease, an acquired valvular degeneration, is the most common cardiac disorder in dogs, affecting approximately 10% of dogs in primary care veterinary practice. Dogs with myxomatous mitral valve disease frequently require anaesthesia for routine procedures. The American Society of Anesthesiologists physical status classification system shows increasing mortality with higher grades, but its subjectivity limits risk stratification in dogs with preclinical myxomatous mitral valve disease. Because Stage B1 and B2 dogs can vary widely in disease severity, even within the same American Society of Anesthesiologists category, a single American Society of Anesthesiologists score may not accurately reflect their anaesthetic risk. While a comprehensive echocardiogram remains the gold standard for myxomatous mitral valve disease staging, referral to a veterinary cardiologist is often cost-prohibitive and might involve long waiting periods. This narrative review proposes a practical framework for pre-anaesthetic risk assessment and protocol selection in dogs with myxomatous mitral valve disease, integrating accessible diagnostic tools including physical examination, radiographic measurements (vertebral heart size and vertebral left atrial size), cardiac biomarkers (N-terminal pro-B-type natriuretic peptide) and point-of-care ultrasound. Recommended anaesthetic protocols are provided for different clinical scenarios ranging from cases with limited diagnostics through grey zone presentations to confirmed cardiomegaly, alongside structured approaches to managing intraoperative complications. This spectrum of care approach recognises that while specialist evaluation remains ideal, practical alternatives can guide safe anaesthetic management for this commonly encountered cardiac condition in companion dogs.