Long-term clinical management of right-to-left ("reversed") patent ductus arteriosus in 3 dogs

A small number of dogs with patent ductus arteriosus (PDA) have right-to-le ft flow of blood through the ductus, leading to polycythemia and clinical s igns associated with hyperviscosity. Three dogs with right-to-left-shunting PDA are described. Treatment consisted solely of phlebotomy, performed on an outpatient basis when indicated by exacerbation of clinical signs, for a total of 11-68 times on each dog. Each treatment entailed the removal of a mean of 19% (maximum 28%) of circulating blood volume, divided into 2 phle botomies several hours apart, without intravenous fluid replacement. Subjec tively, marked clinical improvement was noted. Intermittent clinical signs decreased in frequency and severity in all dogs. Adverse effects were rare (1 for 98 phlebotomies) and reversible. Dogs lived >2 to >8 years during tr eatment. Outpatient phlebotomy without fluid replacement was safe, and was associated with subjective improvement and prolonged survival in these dogs .