Patent Ductus Arteriosus in the older Dog.

OBJECTIVES: The objectives of this study were to describe the clinical course of Patent Ductus Arteriosus (PDA) in older canine patients (defined as patients greater than 24 months at the time of presentation) with and without intervention. This study was also undertaken to evaluate if adult dogs with persistent flow across the ductus should still be closed, what the benefits are from late closure, and to hypothesise why some animals still continue to deteriorate despite closure. BACKGROUND: Currently accepted therapies for patent ductus arteriosus are surgical ligation and transcatheter coil embolisation. The majority of dogs are diagnosed and treated at young age. Some older dogs survive with few clinical signs and live a normal life span without intervention. Some dogs deteriorate despite intervention. METHODS: The case records of 24 dogs that had reached 24 months of age before diagnosis were reviewed and those animals that had no concurrent congenitaal cardiac diseases were included in the study (n = 21). Those animals that were still alive were requested to participate in a long-term follow-up study. RESULTS: After closure of the ductus (n = 16), the clinical signs disappeared in all but one animal. On follow-up of these animals, there was echocardiographic evidence of left ventricular systolic and diastolic dysfunction in many. Late cardiac death was recorded in 3 animals. In dogs where there was no intervention congestive heart failure was a common, but not an inevitable sequel. Development of mitral valve endocardiosis was a common feature. CONCLUSIONS: Older animals with PDA follow an individual course, independent of pre-existing heart failure. Irreversible left ventricular dysfunction is common, however it does not seem to affect the clinical course. These data show a favourable outcome in a high percentage of adult dogs diagnosed with PDA that undergo closure. Outcome without intervention was less favorable.