Clinical features and outcome of dogs and cats with bidirectional and continuous right-to-left shunting patent ductus arteriosus

Abstract

Background: Studies describing the clinical progression of animals with reverse patent ductus arteriosus (PDA) are lacking.

Objectives: To describe the signalment, presenting signs, echocardiographic features, and survival in a group of dogs and cats with bidirectional and continuous right-to-left PDA.

Animals: Forty-six client-owned animals included, comprising 43 dogs and 3 cats with bidirectional or continuous right-to-left PDA.

Methods: Retrospective multicenter study. Medical records and echocardiographic findings reviewed from animals diagnosed with bidirectional or continuous right-to-left PDA. Impact of ductal morphology, spectral Doppler flow profile, PCV, sildenafil treatment at presentation, sildenafil dose, severity of pulmonary hypertension, general anesthesia with or without surgery and the presence of right-sided congestive heart failure (R-CHF) on crude mortality rate were evaluated via Mantel-Cox log rank comparison of Kaplan-Meier survival curves. Univariable and multivariable Cox proportional hazards analysis was performed, and hazard ratio (HR) (95% confidence intervals [CI]) was presented.

Results: Hindlimb collapse was the most common presenting sign in dogs (n = 16). Clinical signs in cats were variable. Median survival time was 626 days in dogs (range 1-3628 days). Dogs with R-CHF had a shorter median survival time (58 days vs 1839 days, P = .03). Dogs treated with sildenafil at initial presentation survived longer (1839 days vs 302 days, P = .03), which was the only independent predictor of survival (HR 0.35, CI 0.15-0.86, P = 0.021).

Conclusions and clinical importance: Dogs and cats with reverse PDA have a variable clinical presentation and prognosis. Survival time was longer in animals prescribed sildenafil at diagnosis. Dogs with R-CHF at presentation have a worse overall outcome.

Keywords: congenital heart disease; polycythemia; right-sided congestive heart failure; sildenafil.

FIGURE 1

Median PCV values of dogs grouped according to initial presenting signs of hindlimb collapse, signs of neurological disease, exercise intolerance, and dogs who were asymptomatic

FIGURE 2

Kaplan‐Meier curve to show overall survival of dogs with bidirectional or right‐to‐left shunting patent ductus arteriosus (PDA)

FIGURE 3

Kaplan‐Meier curves to explore the difference in median survival time between dogs treated with sildenafil and those not treated with sildenafil in dogs with bidirectional or right‐to‐left shunting patent ductus arteriosus (PDA)

FIGURE 4

Kaplan‐Meier curves to explore the difference in median survival time between dogs receiving sildenafil dose <3 mg/kg/d and those receiving sildenafil dose ≥3 mg/kg/d in dogs with bidirectional or right‐to‐left shunting patent ductus arteriosus (PDA)

FIGURE 5

Kaplan‐Meier curves to explore the difference in median survival time between dogs in right‐sided congestive heart failure (R‐CHF) compared to those without R‐CHF in dogs with bidirectional or right‐to‐left shunting patent ductus arteriosus (PDA)