Chylothorax in Dogs

Overview of Canine Chylothorax

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

Signs of chylothorax in dogs may include:

Diagnosis of Chylothorax in Dogs

If your pet is diagnosed with chylothorax, he will require veterinary care. Your veterinarian’s efforts will be directed at two things: making your pet more comfortable by removing as much of the fluid from the chest cavity as possible, and performing tests to determine whether there is an identifiable cause for the chylothorax. Diagnostic tests that your veterinarian may wish to perform include:

Treatment of Chylothorax in Dogs

Home Care and Prevention

In addition to observing your pet closely for evidence of difficult breathing, you may also be asked to administer various medications. Be sure that your veterinarian shows you how to determine if your pet is having difficulty breathing and how to administer any prescribed medications.

If your pet is unwilling to eat commercial low-fat diets, your veterinarian should be able to provide you with recipes for homemade low-fat diets.

There is very little that you can do to prevent your animal from developing chylothorax. In many animals the underlying cause of the chylothorax is never determined.

Chylothorax can occur secondary to heart failure associated with heartworm disease; therefore, be certain to discuss your pet’s need for heartworm prevention with your veterinarian.

In-depth Information on Chylothorax in Dogs

The thoracic duct is a lymphatic vessel that carries chyle from the intestines and into the chest where it empties into the bloodstream. Many of the conditions that cause chylothorax do so because they increase pressure in the blood vessels into which the thoracic duct empties. This increased pressure causes the chyle to “back up” in the duct and many new lymphatics are formed trying to bypass this obstruction. Because these lymphatics are very thin walled, they leak when there is pressure on them. Thus, the chyle seeps from the vessels and accumulates in the chest cavity.

One of the most important aspects of treating chylothorax is to determine the underlying cause so that the treatment can be tailored to the cause. Unfortunately, in many animals the underlying cause is not determined and the condition is termed idiopathic. Some of the causes of chylothorax that have been recognized in dogs include:

In-depth Information on Diagnosis

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:

Diagnostic tests are needed to confirm that the fluid is chyle. Some of these tests include:

Diagnostic tests to determine if there is an underlying disease present include:

In-depth Information on Treatment

Treatment of chylothorax may be divided into either medical management or surgical treatment. Note that some animals do resolve the condition on their own, probably because they reroute the chyle into alternate lymphatics and blood vessels in their abdomen.

The initial concern in treating your pet will be to improve his ability to breathe. Your veterinarian will generally remove the fluid in your pet’s chest cavity using a needle. Occasionally, sedation or anesthesia will be required but a chest tap can often be performed with the animal awake. Depending on the degree of difficulty that your animal is experiencing breathing, oxygen therapy may be required. Further treatment will depend on whether an underlying disease was identified or whether the condition is thought to be idiopathic (no underlying disease found).

Medical management is usually considered first for the treatment of idiopathic chylothorax. It usually consists of intermittent chest taps to allow your pet to breathe more easily, dietary modification and drug therapy. If medical management is unsuccessful, surgery may be considered.

Medical Management of Chylothorax in Dogs

Surgical Therapy of Chylothorax in Dogs

Follow-up Care of Dogs with Chylothorax

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not rapidly improve.