Long‐Term Outcome in Dogs with Patent Ductus Arteriosus: 520 Cases (1994–2009)

BACKGROUND Published information regarding survival and long-term cardiac remodeling after patent ductus arteriosus (PDA) closure in dogs is limited. OBJECTIVES To report outcome and identify prognostic variables in dogs with PDA, and to identify risk factors for persistent remodeling in dogs with a minimum of 12 months of follow-up after closure. ANIMALS Five hundred and twenty client-owned dogs. METHODS Retrospective review of medical records of 520 dogs with PDA. Outcome was determined by contacting owners and veterinarians. Dogs with PDA closure and ≥ 12 months of follow-up were asked to return for a re-evaluation. RESULTS In multivariable analysis of 506 dogs not euthanized at the time of diagnosis, not having a PDA closure procedure negatively affected survival (HzR = 16.9, P < .001). In 444 dogs undergoing successful PDA closure, clinical signs at presentation (HzR = 17, P = .02), concurrent congenital heart disease (HD) (HzR = 4.8, P = .038), and severe mitral regurgitation (MR) documented within 24 hours of closure (HzR = 4.5, P = .028) negatively affected survival. Seventy-one dogs with ≥ 12 months follow-up demonstrated a significant reduction in radiographic and echocardiographic measures of heart size (P = 0) and increased incidence of acquired HD (P = .001) at re-evaluation. Dogs with increased left ventricular size and low fractional shortening at baseline were more likely to have persistent remodeling at re-evaluation. CONCLUSIONS AND CLINICAL IMPORTANCE Patent ductus arteriosus closure confers important survival benefits and results in long-term reverse remodeling in most dogs. Clinical signs at presentation, concurrent congenital HD, and severe MR negatively affect survival. Increased left ventricular systolic dimensions and systolic dysfunction at baseline correlated significantly with persistent remodeling.