Coping with Canine Chylothorax: Symptoms & Treatment So

One of the most critical aspects of treating chylothorax is identifying the underlying cause. This allows for targeted treatment that addresses the root of the problem. Unfortunately, in many animals, the exact cause remains unknown, a condition referred to as idiopathic. However, several potential causes of canine chylothorax have been identified, including:

1. Mediastinal Masses (Lymphosarcoma, Thymoma). These masses grow within the mediastinum or the space between the lungs. As they grow, they may partially obstruct the vessels that lead to the thoracic duct.

2. Congenital Heart Disease (Tetralogy of Fallot, Tricuspid Valve Dysplasia). These conditions increase the pressure on the heart and the vessels leading to the thoracic duct, leading to lymphatic fluid accumulation. Similar to mediastinal masses, new lymphatic vessels may form, which simply leak chyle into the chest cavity.

3. Myocardial Disease. This is a chronic heart condition where the heart cannot contract normally. Like congenital heart disease, it can raise blood pressure, leading to chyle leakage into the chest.

4. Pericardial Effusion. This is the fluid that accumulates around the heart. When fluid collects here, it increases blood pressure, and the thoracic duct usually empties into these vessels.

5. Heartworm Infection in Dogs. Heartworm infection can lead to heart failure, thereby increasing the pressure on the vessels leading to the thoracic duct.

6. Fungal Granulomas. Abnormal collections of cells and fungi can block the vessels leading to the thoracic duct.

7. Venous Thrombosis. Blood clots can obstruct the vessels leading to the thoracic duct. This can occur after a catheter is inserted into the jugular vein.

8. Congenital Abnormalities of the Thoracic Duct. Abnormalities in the thoracic duct have been described in Afghan Hounds, which may explain why they are more prone to this disease than most other breeds.

9. Trauma is a rare cause of canine chylothorax, but it is often discovered after a car accident or severe vomiting. Chylothorax caused by trauma has a good prognosis, as the thoracic duct can heal quickly without surgery.

Further Insights into Diagnosis

Veterinarians will conduct specific diagnostic tests to determine if there is fluid in the chest, confirm if the fluid is chyle, and identify any underlying diseases that may be causing the accumulation, such as heart disease or tumors.

Diagnostic tests to determine the presence of fluid in the chest include:

1. A thorough medical history and a complete physical examination.

2. A careful auscultation of the chest (using a stethoscope) to determine if heart and lung sounds are normal. When fluid is present, heart sounds may be muffled. If heart disease is present, murmurs may be heard.

3. Chest radiography (xray) to differentiate chest fluid, determine the amount and location of the fluid, and assess for other causes of respiratory distress, such as pneumonia, asthma, tumors, or fluid formation.

Afterward, veterinarians will perform further diagnostic tests to confirm if the fluid is chyle. These tests include:

1. Analysis of the physical characteristics (color, clarity) of the fluid extracted from the chest, the type and number of cells, the amount of protein, and the quantity of triglycerides (fat) in the fluid.

2. Triglyceride content measurement. Chyle has a higher triglyceride content than serum. To compare, blood can be drawn from your dog and triglyceride levels measured.

3. The typical composition of chyle is mainly lymphocytes and neutrophils, which are also normal cells found in blood. Veterinarians typically perform a detailed analysis to determine if there are any tumor cells in the chest.

4. Veterinarians also usually check for the presence of any abnormal bacteria or cells in the fluid, which may indicate the presence of an infection.

Veterinarians will also conduct some diagnostic tests to determine if there are underlying diseases, including:

1. An ultrasound of the chest before fluid extraction to determine if there is a tumor (mediastinal mass) in front of the heart. Ultrasound is very helpful in evaluating chest masses or other abnormalities when fluid is present in the chest.

2. An echocardiogram to determine if the heart function is normal, if there are heart lesions (such as valve abnormalities), or if there are congenital heart defects, if there is thickening or effusion around the pericardium, or if there is a heart tumor.

3. Heartworm testing.

4. Repeating chest radiographs after fluid extraction to determine if the lungs have reinflated. Fibrotic pleurisy – thickening and scarring of the lung and chest wall – may be associated with chronic chylothorax, leading to the lungs not being able to reinflate normally.

5. Routine blood tests, including a complete blood count (CBC) and serum biochemical tests, are often used to help assess the dog's organ function and overall health.

Your veterinarian may recommend other tests to help further differentiate the underlying diseases of chylothorax or identify any concurrent diseases.