Lymphedema is the collection of lymph fluid in body tissues due to obstruction within the lymphatic system. The lymphatic system consists of organs, vessels and nodes. The vessels absorb protein rich fluid that has escaped into body tissues from capillaries. The fluid is returned back to the bloodstream to ensure that the cardiovascular system has enough blood volume to function properly.
Lymph nodes are glands that exist in hundreds throughout the body tissues. Lymph nodes filter the fluid, or lymph, that is being returned to the bloodstream. These glands also make lymphocytes, the most important cells for immune system function.
Lymphedema can occur in dogs as an acute or chronic condition. It can be a primary disorder or a secondary disorder to an associated condition. Primary lymphedema usually presents symptoms before a dog matures. Some dogs are symptomatic of primary lymphedema at birth. English bulldogs, Old English sheepdogs, Labrador retrievers and poodles are believed to be congenitally predisposed to the condition.
Causes and Associated Conditions of Lymphedema
Lymphedema may be idiopathic, or occur with no known cause. Lymphedema is caused by an obstruction of the flow of lymph fluid in lymphatic vessels or through lymph nodes. Obstruction of flow can be caused by lymphangitis or lymphadenitis. Lymphangitis is an inflammation of the lymph vessels and lymphadenitis is an inflammation of the lymph nodes. Compression from surrounding tissue can also obstruct the flow of lymph fluid in vessels and nodes. Compression or inflammation can occur with conditions such as:
- Congenital aplasia (defect or absence of an organ or body tissue)
- Hyperplasia (abnormal increase in organ or tissue size)
- Hypoplasia (incomplete development of an organ or tissue)
- Neoplasia (tumor formation)
- Trauma
- Radiation therapy
- Organ enlargement
Symptoms of Lymphedema in Dogs
The obstruction of lymph fluid flow causes it to collect in the tissues of the body. Although internal, this collection of fluid will eventually become visible on the outside of the body. Visible signs of swelling include regions of the body such as the:
- Feet
- Legs (usually begins at foot)
- Chest
- Abdomen
- Extremities (ears or tail)
The dog may eventually exhibit other symptoms that are caused by fluid retention in the swollen limbs. These symptoms include:
- Lameness
- Pain
- Lethargy
- Discoloration of skin (in affected body region)
- Delayed healing
Symptoms may be exaggerated if the dog's immune system is resisting an unrelated disease.
Clinical Diagnosis of Lymphedema
A symptomatic dog that is suspected of lymphedema will require laboratory tests to confirm the diagnosis. A veterinarian will recommend blood work and a urinalysis. Aspiration of the body tissue may done to determine if lymph fluid is present in the swollen body region. A veterinarian may also recommend a lymphangiography. A lymphangiography procedure involves the injection of dye into the lymphatic system, followed by radiographs (x-rays).
Therapy for Symptoms of Lymphedema
Lymphedema cannot be cured or prevented. Treatment is aimed at controlling the symptoms caused by the disorder. A healthy diet and an environment that is free of allergens can help to reduce the symptoms. Maintaining good health will reduce the chances of an immune system reaction and therefore the amount of work the lymphatic system has to do. Swelling can be reduced in the affected limbs with pressure bandages, head pads and massage. A veterinarian may also prescribe a Benzopyrone medication to help reduce the swelling.