Chylothorax is a condition in which a characteristic type of lymph fluid called chyle accumulates in the chest cavity and causes difficulty breathing. Lymph is the fluid that is drained from tissues and functions to carry protein and cells from the tissues to the bloodstream via small vessels, known as lymphatics. When the lymph is drained from the intestines, it contains a high quantity of fat and is known as chyle. Thus, chylothorax is a collection of chyle in the chest cavity. The accumulation of chyle in the chest cavity leads to difficulty breathing because the lungs cannot expand normally to take in oxygen.

This condition may occur in any breed of dog, but some breeds appear to have a higher than expected incidence, including Afghan hounds and shiba inu dogs. Afghan dogs appear to develop signs related to this disease when they are middle-aged, whereas the shiba inu is often less than a year of age when the condition is diagnosed.

Chylothorax is most common in middle-aged and older animals, but can occur in very young animals as well.

The cause of the chylothorax in many animals idiopathic, which means the cause is not determined. However, some animals are determined to have tumors, heart disease or blood clots that elevate pressures in the bloodstream and cause the chyle to leak from the lymphatic vessels in the chest. It is important that underlying causes be identified and treated whenever chylothorax is diagnosed.

What to Watch For

Coughing

Difficulty breathing

Decreased appetite

Lethargy

Cyanosis