Fluid Buildup in the Sac Surrounding the Heart in Dogs

In the normal anatomy of a canine, there is the presence of a very thin membrane surrounding the heart which serves as protection. A small amount of fluid is required to act as a lubricant; it is abnormal and dangerous when fluid builds up continually (and in many cases rapidly), causing the heart to become enlarged. When this happens, there can be compression of the esophagus, bronchi or lungs. Intracardiac pressure, affecting the heart itself, leads to decreased filling of the heart, decreased cardiac output and subsequently, shock to the system. Examples of causes for pleural effusion may be infection or right-sided heart failure. Prognosis varies and it must be considered a life-threatening condition.

When there is an accumulation of fluid within the pericardial sac, it is known as pericardial effusion. How much this abnormality will affect your pet will depend on the rate of fluid flow into the sac as well as the amount of fluid that accumulates.

Symptoms can evolve to a dangerous level whereby the situation becomes life threatening. These are the signs you may see in your pet, depending on the extent of the effusion.

• Loss of appetite or willingness to eat
• Lethargy
• Fainting
• Difficulty breathing
• Vomiting
• Weakness
• Exercise intolerance
• Weight loss
• Coughing
• Difficulty swallowing
• Pale mucus membranes
• Abdominal distention
• Collapse

Types

Fluid buildup in the sac surrounding the heart can happen due to congenital illnesses (present at birth) or due to acquired diseases that develop throughout life. The effusion can be chronic and of a progressive nature, or acute which means the event came on suddenly.

Some of the recognized reasons for pericardial effusion are:

• Tumor
• Bacterial infection
• Fungal infection
• Migrating foreign body such as Foxtail
• Mitral valve disease which causes left atrial rupture; small breeds are predisposed
• Coagulation disorders
• Congestive heart failure
• Congenital hernia
• Idiopathic hemorrhagic pericardial effusion; large and giant breeds are prone

It is documented that German Shepherds and Golden Retrievers are predisposed to a fluid buildup in the pericardial sac.

The physical examination performed by the veterinarian will include listening to the heart and taking the pulse, two indicators of the heart’s performance. The pulse of your dog will most likely be poor or low if he is in a state of advanced pericardial effusion. The heart sounds that the veterinarian is trying to distinguish will most likely be of a muffled nature because of the volume of fluid buildup. If there is right side heart failure, there may be jugular vein distortion apparent during the exam.

Standard tests that will be ordered are the blood chemical profile, complete blood count, and urinalysis. Tests that will give further diagnostic leads are radiographs. Abdominal x-rays could show fluid in the abdomen as well, and thoracic x-rays  can show the heart size and signs of metastatic disease if this is the case. An echocardiogram is a type of ultrasound that can clearly identify fluid buildup and determine present functioning state of the heart, and can show other problems such as a hernia. An electrocardiograph will tell the veterinarian the state of electrical activity in your pet’s heart.

The treatment for pericardial effusion is pretty straightforward in that the essential need is to remove the excess fluid from the sac surrounding the heart. However, as simple as it sounds, it can be complicated if the amount of fluid has caused further developments and damage to the body of your dog. Cardiac tamponade for example, is when the fluid causes compression to the heart, a very severe situation resulting from the fluid buildup. Right side heart failure can occur, which promotes the accumulation of fluid in the abdomen. The removal of fluid is done by a procedure called a pericardiocentesis. A needle or catheter is inserted into the sac around the heart, aspirating the liquid. In cases where there is fluid in the abdomen as well, this will be taken out in addition.

Some canines will need surgery if the effusion returns. A pericardiectomy involves making a window in the sac which allows the continuous flow of liquid to move into the chest cavity. It should be noted that both of these procedures can have a good to poor prognosis, depending on the body’s response to the treatment. Of course, as with any procedure involving the heart especially, there are risks and the possibility of failure. In the instance of an infection, parasitic invasion, or underlying disease process, the appropriate measures in the form of antibiotics or medication will be addressed.

There are chances that your pet may not recover from a heart procedure. However, it depends on the cause. Parasitic invasion, infection, and hernia can have a successful recovery depending on the extent of the problem. If your beloved pet has a tumor that is slow growing, he may have a fair to good prognosis. If your pet has pericardial effusion that keeps returning, the situation may be described as poor to guarded because continual effusion can change the pliability of the heart sac making it vulnerable to disease. Your veterinarian will do her best to prolong the life of your pet as long as the quality of life we all want for them is there.