Use of sodium nitroprusside in the anaesthetic protocol of a patent ductus arteriosus ligation in a dog.

Patent ductus arteriosus (PDA) is one of the most common congenital cardiac abnormalities in the dog. Sodium nitroprusside has been proposed as an infusion during PDA ligation as the resultant nitric oxide production causes hypotension thereby facilitating surgical dissection and decreasing the risk of haemorrhage. This case report details how the method described did not decrease blood pressure and therefore had no beneficial effects. It is speculated that the lack of response may have been due to tachyphylaxis. Other drugs may be preferred to induce deliberate hypotension in the dog.