At what age and frequency should Cavalier King Charles Spaniels be screened for mitral valve disease?

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Cavalier King Charles Spaniels (CKCSs) should begin cardiac screening at 1 year of age, with annual auscultation and echocardiography thereafter, given that 50% of the breed is affected by myxomatous mitral valve disease (MMVD) by age 6–7 years and nearly 100% by age 11.12 The Danish Kennel Club mandatory breeding scheme, which combines auscultation and echocardiography, reduced the odds of mitral regurgitation murmur by 73% over an 8–10 year period in dogs that were products of the scheme, compared to no significant change in non-products.5 The UK breed scheme, which relied on auscultation alone, showed a benefit only in a subgroup — bitches examined by general practitioners showed murmur detection age increase from 8.6 to 9.2 years — but no benefit was seen in male dogs or dogs examined by cardiologists, and breeder compliance was poor.3 Echocardiography is the gold standard for MMVD staging and should not be replaced by auscultation alone. The presence of a heart murmur does not reliably discriminate between ACVIM stage A and stage B1 MMVD in CKCSs.13 Among individual non-echocardiographic screening tests, N-terminal pro-B-type natriuretic peptide (NT-proBNP) and vertebral heart size (VHS) have the best discriminatory ability for identifying stage B2 disease, with areas under the curve of 0.855 and 0.843, respectively.12 An NT-proBNP ≥ 1138 pmol/L carries 90.1% specificity for stage B2, and a VHS ≥ 11.5 carries 90.6% specificity for stage B2.12 Breed-specific radiographic reference values must be used when interpreting VHS in CKCSs. The breed-specific VHS mean is 10.08 ± 0.56 (95% range 9.87–10.29), which is significantly higher than the general canine reference of 9.7 ± 0.5.2 Breed-specific mean VLAS is 1.79 ± 0.3 (95% range 1.68–1.9), modified VLAS is 2.23 ± 0.44 (95% range 2.06–2.39), and radiographic left atrial dimension is 1.2 ± 0.34 (95% range 1.07–1.33) — all significantly lower than previously published general canine reference values.2 Prognosis is infl