Usually there is only a small amount of accumulated extra fluid in a dog's body . However, conditions like congestive heart failure can cause a dog's body to become bloated and filled with liquid. Sometimes there is so much of this fluid that the dog's body weight can nearly double! Unfortunately this may be just the beginning. Heart problems can also trigger a secondary condition called canine protein-losing enteropathy (CPLE) that can cause even more fluid to build up, plus a host of other potentially life-threatening complications .
CPLE occurs when higher than normal amounts of protein leak into the intestinal tract and are lost through the stool. Although the dog's body tries to make up for this loss by producing more proteins like albumin, it can't keep up with the demand. As a result, the dog has low levels of albumin (hypoalbuminemia) and sometimes low levels of globulin (hypoglobulinemia).