Chylothorax in Cats

Anatomy of a Cat’s Chest Cavity

The thoracic cavity houses different vital organs involved in many different important bodily functions. This is where major blood vessels and nerves cross to provide blood supply, oxygenation, and innervation across different organs in the cat’s entire body. This is also where the esophagus passes through and facilitates the transit of food from the animal’s mouth to the stomach.

But the main organs in the thoracic cavity are the lungs and heart. These organs work together to make sure the blood supply and oxygenation of all other organs in the cat’s body are consistent and distributed efficiently.

During inhalation, the lungs inflate to accommodate as much air and maximize oxygen exchange. This is achieved through the help of different muscles in the chest area, particularly the diaphragm. Contraction of the diaphragm allows the chest cavity to expand for the lungs to inflate and maximize the amount of air being inhaled during breathing.

The diaphragm also helps push out air from the lungs during exhalation by relaxing and reducing the thoracic space. The thoracic cavity needs to maintain negative pressure between the lungs and the thoracic wall, called the pleural space, to allow the lungs to expand and contract during breathing. Any disease that occupies even the smallest part of the animal’s pleural space will result in inefficient lung inflation and contraction, leading to breathing problems.

What is Chylothorax?

Chylothorax is a rare condition in cats described as the accumulation of lymphatic fluid, also known as chyle, in the animal’s pleural space. Chyle is a milky-white fluid substance originating from the lymphatic system, particularly intestinal lymphatic drainage. The lymphatic fluid, coming from the intestinal lymphatic drainage, is rich in triglycerides, giving it a distinct color and odor.

Normally, lymphatic drainage from the intestines is transported and drained into the cranial vena cava via the thoracic duct, one of the main vessels of the lymphatic system. When cats develop chylothorax, the fluid gets drained to the pleural space instead.

Causes of Chylothorax in Cats

One of the most common causes of chylothorax in cats is physical trauma. Any forceful physical injury in the abdominal or chest region, such as automobile accidents, can damage the thoracic duct. This causes the lymphatic fluid from inside the vessel to leak into the pleural space.

An increase in the pressure in the thoracic duct or vena cava can also lead to the development of chylothorax in cats. Conditions like congestive heart failure, fungal infections, heartworm disease, or thoracic tumors are some of the most common causes of increased pressure in these vessels.

In some cases, the specific cause cannot be determined even after a proper physical and diagnostic exam. In the situation where a specific cause cannot be identified, the condition is called idiopathic chylothorax. This accounts for around half of chylothorax cases in cats.

Symptoms of Chylothorax in Cats

Since chylothorax results in the insufficient expansion of the lungs during respiration, the most common clinical sign seen in cats affected by the condition is labored breathing. Some cats may appear to hold their breath occasionally due to the delay between inhalation and exhalation during breathing.

Initial signs of the condition in cats include coughing, a decrease in the pet’s appetite, and generalized weakness. Since coughing is not a commonly encountered symptom in other types of pleural effusion (fluid in the chest), it can be a good indicator that the fluid accumulating in the feline patient’s pleural space is chyle.

However, these signs are not specific to chylothorax in cats, and many other conditions can present with the same symptoms. If you start to observe any of the signs mentioned above, it’s best to see your veterinarian for a proper medical exam right away.

Diagnosing and Treating Chylothorax in Cats

Diagnosis for chylothorax in cats is based on clinical signs, medical history, and diagnostic imaging. The condition is considered in cats that have breathing difficulties and a history of possible physical trauma. Listening to the chest area with a stethoscope can reveal possible fluid accumulation in the cat’s pleural space.

Diagnostic imaging such as radiographs and CT scans can confirm the presence of fluid in the pet’s pleural cavity. Definitive diagnosis for chylothorax can be obtained by analyzing the fluid from the patient’s pleural cavity. Your vet will then run a few other tests such as heartworm tests or tests for specific viral diseases to figure out what caused the accumulation of lymphatic fluid.

Treatment will depend on the specific cause of chylothorax, and as such a proper diagnosis is essential. Placing a chest drain surgically can help remove the fluid inside the pleural cavity and help the patient breathe easier, but fixing the specific underlying condition is needed to prevent recurrence of the problem.

Read more:

Pyothorax in Dogs and Cats

Pneumothorax in Dogs and Cats

Treating and Preventing Abscesses in Cats

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