Chylothorax in Dogs

Chylothorax is a condition caused by a buildup of lymph fluid in the chest cavity. Lymph is a bodily fluid that carries protein and cells to tissues through small vessels known as lymphatics. The lymph fluid that accumulates in the chest cavity contains a high quantity of fat and is called “chyle.” Since thorax means “chest cavity,” the name chylothorax simply means a buildup of this fatty lymph fluid in the chest.

When chylothorax occurs, the lungs can’t expand normally, which reduces the intake of oxygen and causes breathing difficulties. The exact cause of this disease is not known. It is seen more often in dogs with heart disease, heartworms, blood clots, or tumors, but often no obvious cause is identified. While this condition can occur in any breed of dog, the Afghan hound and Shiba Inu experience a higher-than-average incidence of it.

If your dog is suffering from this condition, you might observe the following:

  • Difficulty breathing
  • Cyanosis (a bluish tinge to the skin/mucous membranes, due to a reduction in oxygen)
  • Lethargy
  • A decrease in appetite
  • Coughing

Chylothorax is a serious condition. If your pet is diagnosed with this, she will require immediate veterinary care. Your veterinarian will remove the fluid from your dog’s chest cavity to make her more comfortable, and then will look for the underlying cause.

They may recommend the following tests:

  • A radiograph (x-ray)
  • Analysis of the chest fluid, looking for a possible cause
  • A blood test to rule out heartworm
  • A CBC and chemistry profile to assess your dog's overall health
  • A blood pressure test
  • Thoracic ultrasound (which may include a look at your pet’s heart)

If an underlying cause is found, treating it may help to resolve the chylothorax. During treatment, your veterinarian may recommend continued removal of the chest fluid to keep your dog comfortable.

If no underlying cause is identified, your veterinarian will recommend a treatment plan that is right for your pet. It may include periodic removal of built-up fluid, a low-fat diet, and, possibly, surgery—if the condition does not resolve.

There is very little you can do to prevent your pet from developing chylothorax. In many cases, the underlying cause is never identified. One underlying cause can be heartworm disease, so discuss the prevention of this disease with your veterinarian.

If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.

Feline Chylothorax

Normally, there is a little bit of clear liquid in the pleural cavity (space between the lungs and chest wall). This makes sure that the lungs do not stick to the wall.

Chylothorax is a rare condition when there is too much liquid in the cavity. This can be fatal, as the lungs cannot expand fully.

There are two possible scenarios:

  1. Pleural effusion: fluid invades the cavity, restricts lung expansion, and makes it difficult to breathe
  2. Milky white fluid containing fat replaces the clear fluid in the cavity: more dangerous because the liquid is thicker and breathing is even more difficult

Both scenarios are emergencies, leading to respiratory failure and death.

More than half of chylothorax cases are idiopathic (the cause is unknown).

Some possible causes include:

  • Tumors
  • Heartworms
  • Heart disease, blood clots, high blood pressure
  • Trauma to the chest: falls, car accidents

  • Difficulty breathing (your catmay look like it's holding its breath)
  • Coughing (not natural in cats)

Other possible signs include:

  • Depression, lack of energy
  • Loss of appetite
  • Blue skin because of the lack of oxygen

If your cat has any trouble breathing, go to the veterinarian immediately.

In order to diagnose your cat with chylothorax, your veterinarian may perform the following:

  • Physical examination: specifically listening to the chest with a stethoscope
  • Chest x-ray
  • Chest tap: fluid is removed and studied

Additional tests to determine the underlying cause may include:

  • Ultrasound of the heart
  • Abdominal x-rays
  • Blood tests
  • Testing the fluid for bacteria

Most veterinarians will recommend the following treatments for cats with chylothorax:

  • Stabilizing breathing: fluid is drained
  • Treating the underlying disorder
  • Feeding a low fat diet
  • Rutin: a supplement that stimulates the cells which carry away the fat that's in the liquid

In many cats, the underlying cause of chylothorax is never determined, and therefore, cannot be prevented.

Chylothorax can occur as a symptom of heart failure caused by heartworm disease. Discuss heartworm prevention with your veterinarian.

There is a good prognosis with treatment to stabilize breathing and for any underlying conditions.

Since the excess liquid irritates the heart and lungs, scar tissue may form. It will press on the lungs, causing breathing difficulty and long-term damage. Therefore, you must go to the veterinarian as soon as you notice signs.

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Canine Chylothorax in Dogs - pets

Follow-up visits: * Three to 6-months post-surgery for a follow-up CT study * Nine months to 1-year post-surgery for chest x-rays

If you allow your dog to participate in this study, you will be responsible for bringing the dog to the VMTH for all study-related visits. Additionally, you will need to cover any costs related to complications and some of the costs associated with the surgical procedure (e.g., surgical procedure and related fees, anesthesia for surgery, ICU fees and hospitalization fees associated with the first visit).

We are looking for dogs diagnosed with idiopathic chylothorax. We cannot include dogs that have been diagnosed with any significant degree of pericardial disease or other underlying etiologies (non-idiopathic chylothorax).

Prior to being accepted into the study, patients will have to get a thorough diagnostic assessment to rule out underlying causes and confirm a diagnosis of idiopathic chylothorax (IC), which must include a complete blood count and biochemistry screen completed within a month from the date of surgery. Triglyceride levels assayed in the serum and in the pleural effusion must confirm the diagnosis of IC and a heart worm antigen test must be negative. Patients must also have undergone thoracic radiographs and abdominal ultrasonography.


Since the lungs are mainly affected by the fluid buildup, the signs and symptoms of chylothorax in dogs are often similar to other respiratory diseases characterized by an impediment to lung expansion like pneumothorax. Symptoms include:

  • Breathing difficulty
  • Non-productive cough
  • Lethargy
  • Rapid and shallow breathing
  • Loss of appetite
  • Weight loss

Over time, the dog may suffer from inflammation of the lungs and pericardium, compromised immune system, as well as irreversible damage to the lungs or heart, if left untreated.

Use of Omentum as a Physiologic Drain for Treatment of Chylothorax in a Dog

From the Small Animal Teaching Hospital, The University of Liverpool, Crown Street, Liverpool, UK.

From the Small Animal Teaching Hospital, The University of Liverpool, Crown Street, Liverpool, UK.

From the Small Animal Teaching Hospital, The University of Liverpool, Crown Street, Liverpool, UK.

From the Small Animal Teaching Hospital, The University of Liverpool, Crown Street, Liverpool, UK.

Address reprint requests to John M. Williams, MA, Small Animal Teaching Hospital, The University of Liverpool, Crown St, Liverpool, L7 7EX, UK.

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Objectives— To describe a novel technique for the surgical treatment of idiopathic chylothorax in a dog.

Animals— A 6‐year‐old, male Rhodesian Ridgeback, which presented with a history of reduced exercise tolerance and dyspnea.

Methods— Idiopathic chylothorax was diagnosed. Intermittent pleural drainage failed to resolve the problem. During surgery, extensive pleural fibrosis made it impossible to identify the thoracic duct. A dorsal omental pedicle was advanced through an incision in the diaphragm and into the cranial thoracic cavity to act as a physiological drain.

Results— The dog recovered well and has remained free from clinical signs of recurrence of the effusion (16 months at the time of writing).

Conclusions— The disease‐free interval achieved in this dog indicates that this novel technique is worthy of further consideration in the management of idiopathic chylothorax.

Watch the video: Dog Chylothorax. Thoracoscopic thoracic duct ligation (September 2021).