In the first few weeks of pregnancy in canines the cell develops and eventually we get the organ systems which function together to keep the body healthy and in working order. Now in regards to the heart we all know its function is to pump blood throughout the body via the circulatory system. However, when in the uterus blood flow to the lungs is unnecessary and this is where the ductus arteriosus comes in. The ductus arteriosus, an important blood vessel, connects the main pulmonary artery to the proximal descending aorta in a majority of species. While the fetus is still developing it makes sure that no blood flow goes to the lungs. During the birth this blood vessel however typically closes off, if it doesn’t then we get the birth defect known as patent ductus arteriosus also known as PDA. In most cases, this defect can be diagnosed at a young age in most species (frequently in dogs and cats) due to routine examinations. However if not caught, clinical signs that a puppy or adult dog has this defect include shortness of breath, coughing, weakness, exercise intolerance and as it progresses ultimately heart failure. Some breeds that are more predisposed to this defect would be the Maltese, Poodle, Pomeranian, Keeshond, Bichon Frise, Chihuahua and German Shepherd. Ways to diagnose this in canines in most cases is when puppies are brought in for routine examination and a heart murmur is heard. From here x-rays would be taken to view the size and shape of both the heart and lungs and/or an ECG which depicts any irregularities in the heart`s rhythm . Once diagnosed treatment available consists of transvenous catheterization, and surgical ligation. Transvenous catheterization is non-invasive and and in most patients is recommended. This treatment consists of making a small incision on the inside of one hind leg and passing a long catheter from the hind leg into the abnormal vessel. A device known as the Amplatz Canine Ductal Occluder is then deployed to stop the irregular blood flow. However, very small dogs require open chest surgery and so surgical ligation is used for these breeds in order to tie the vessel off. This treatment method requires surgery in the chest cavity where the surgeon ties off the vessel itself. Typically if the patent ductus arteriosus is closed correctly most species that undergo the correction will lead a long and normal life span. Some patients however have to remain on PDA medications.