Section: Veterinary Care In-depth
Diagnosis In-depth
Diagnostic tests will be performed to determine that fluid is present in the chest cavity, verify that the fluid is chyle and determine if there is an underlying disease such as heart disease or tumor that might have caused the effusion.
Diagnostic tests to determine that fluid is present in the thoracic cavity include:
A complete medical history and thorough physical examination
Careful auscultation of the chest (using a stethoscope) to determine whether the heart and lung sounds are normal. When fluid is present the heart sounds may appear muffled. If heart disease is present, a murmur may be heard.
Thoracic radiographs (chest X-rays) to identify fluid in the chest and determine how much is present and where it is located. The radiographs will also be evaluated to determine whether other causes of difficult breathing like pneumonia, asthma, or tumor, or fluid formation might be present.
Diagnostic tests are needed to confirm that the fluid is chyle. Some of these tests include:
Analysis of fluid removed from the chest by needle thoracentesis (chest tap) for physical characteristics (color, clarity), the type and number of cells, amount of protein and the amount of triglyceride (fat) in the fluid
Measurement of triglyceride content. Chylous fluid has a higher triglyceride content than serum. To make this comparison, blood may be drawn from your pet and also measured for triglyceride content.
Chylous fluid typically is composed primarily of lymphocytes and neutrophils. These are normal cells that are also present in the bloodstream. The fluid is usually carefully analyzed for the presence of cells that might indicate a tumor is present in the chest cavity.
The fluid is usually checked for bacteria or the presence of cells that might indicate that an infection is present.
Diagnostic tests to determine if there is an underlying disease present include:
Before removing the fluid, your veterinarian may wish to perform an ultrasound on the chest to determine whether a tumor might be present in the area in front of the heart (mediastinal mass). When fluid is present in the chest cavity, ultrasonography is very helpful in evaluating the chest cavity for masses or other abnormalities. It may also be used to guide the chest tap if the fluid is pocketed.
An echocardiogram may be performed to determine if heart function is normal, whether there are cardiac lesions, such as acquired valvular abnormalities, or congenital cardiac defects, whether the pericardium (the sac around the heart) is thickened or contains fluid (pericardial effusion) or whether a heart base tumor is present.
A heartworm test is usually performed.
Repeat radiographs may be taken, after the fluid has been removed, to determine whether the lungs re-inflate. Fibrosing pleuritis – thickening and scarring of the lining of the lungs and the inside of the chest cavity – may be associated with chronic chylothorax and result in the lungs not re-inflating normally.
Routine blood work, including a complete blood count (CBC) and serum biochemical panel, will often be done to help assess organ function and overall health of your pet.
Your veterinarian may recommend other tests to help further identify potential diseases that may have caused the chylothorax or to identify concurrent diseases that might be present.
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