Patent Ductus Arteriosis
Every dog (or cat, or human for that matter) is born with a hole in his or heart. This hole works as a valve and is called the patent ductus. Its function is primarily to shunt blood to the lungs while the puppy is still in its mother's womb, and as such it becomes unnecessary after birth when the puppy can breathe on its own. Because of this, the fissure known as the patent ductus normally closes on its own by the time the animal is three days old. There are times, however, when for whatever reason, this does not occur.
In a normally functioning heart, blood enters the heart on one side and is sent to the lungs to be oxygenated, whereupon it returns to the other side of the heart where it is pumped out to the rest of the body. If the patent ductus does not close, the result is that an inordinate amount of blood is shunted towards the lungs, which causes an increase of fluid on the lungs and labored breathing. [...]
The American Staffordshire Terrier is not among the unhealthiest of breeds, but it does unfortunately suffer from some serious genetic conditions; some of these conditions were not recognized to affect the breed in a serious manner until recently. For example, more and more reports have been coming in of American Staffordshire Terriers (also called Amstaffs) suffering from a variety of problems classified under heart disease, specifically congenital heart disease. Congenital heart disease, or CHD, is a heart condition that is present when the pup is born; it is different from Acquired Heart disease, which is a heart condition that develops later in a dog's life. CHD is rare, but it can result in serious heart failure. [...]