Lymphedema is a medical condition in which localized fluid retention and tissue swelling are caused by a compromised lymphatic system. The swelling may affect one or several limbs, and typically begins at the end of the limb and slowly moves upwards. Most of the time, the cause of your pet’s lymphedema is caused by another illness or injury. For example, swelling of the face could be an allergic reaction to a bug bite. It may be primary or secondary. Primary or congenital lymphedema is usually present at birth or by several months of age.
What Is Lymphedema?
The lymphatic system consists of lymphatic vessels that filter blood, collect lymph (a watery fluid that contains white blood cells), and drain excess fluid from the tissue. The four major functions of the lymphatic system include removal of excessive tissue fluid, transport of waste material to the blood, filtration of lymph fluid by the lymph nodes, and transport of large proteins to the bloodstream.
Lymphedema is a symptom of a medical condition in dogs that is caused by a compromised lymphatic system. Lymphedema is a collection of lymph fluid in body tissues due to obstruction within the lymphatic system. Due to damage or an obstruction in the lymphatic system, a buildup of fluid occurs resulting in swelling of your dog’s legs or other parts of the body, including the face and abdomen.
The causes of lymphedema may be from a chronic illness or an acute condition such as an injury. It may also be a secondary condition stemming from another illness or it can be the primary illness. However, with a primary lymph disorder, the symptoms are usually noticed in a canine when they are puppies under two months of age. The most common and obvious sign of lymphedema is the swelling of one or all extremities or the abdomen.
Signs of Lymphedema in Dogs
The obstruction of the flow 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:
- Legs (usually begins at paw)
- Extremities (ears or tail)
The dog may eventually exhibit other symptoms that are caused by fluid retention in the swollen limbs. These symptoms include:
- Discoloration of skin (in affected body region)
- Delayed healing
Causes of Lymphedema
Lymphedema in dogs may be a congenital defect or hereditary, this is called primary lymphedema. In these dogs, normal lymph vessels or tissue may be completely absent or reduced.
Secondary lymphedema can be caused by heart disorders, trauma, tumors, or infection. Some of these problems result in excessive fluid production that overwhelms the lymphatic drainage system. If damage occurs to the lymphatic system from trauma, surgery, radiation therapy, infection, or cancer, the ability to effectively transport fluid is also affected.
Diagnosis of Lymphedema in Dogs
If you are concerned your dog may have lymphedema, it’s important to see a veterinarian.
Your veterinarian will start by performing a thorough exam and obtaining a history on your dog. When giving the history on your dog, be sure to include if you have given your dog any medication or new foods because the swelling can be related to an allergy.
Your vet will most likely perform a number of diagnostic tests to rule out more common causes of tissue swelling such as heart disease, trauma, or infection and to form a diagnosis. These will most likely include a complete blood cell count, tests for tick borne infections and heartworm disease, evaluations of liver, kidney, and pancreatic functions, electrolyte tests to check for dehydration, blood tests to rule out disease that cause loss of protein and search for evidence of infection and cancer and a fine needle aspirate of the affected area or nearby lymph nodes. A fine needle aspiration (FNA) is performed by collecting cells from the growth on a needle and then transferring them to a slide to look at under the microscope. The FNA is also used for histiocytomas. It is minimally invasive and can be done the same day as your initial exam. If the FNA reveals no cancerous or inflammatory cells, x-rays and /or ultrasound may be recommended. X-rays of the affected limb may be recommended if trauma is suspected. X-rays and/or ultrasound imaging of the abdomen and chest may be performed to evaluate the heart and screen for cancer.
If lymphedema is highly suspected, lymphangiography may be considered. In this procedure, dye is injected below the swollen areas, and the flow is observed through video x-rays (fluoroscopy) or a series of still x-rays. Lymphangiography is often performed at veterinary referral facilities.
Unless a correctable underlying condition is diagnosed, lymphedema is not considered curable. If your vet finds the underlying cause and it is treatable, i.e. allergy or infection, they will treat the cause and swelling will resolve with treatment.
Resting the dog and massage of the affected limb may improve lymph circulation. In some dogs, the use of long-term pressure wraps, and physical therapy are needed. Antibiotics are used to treat secondary infections. Surgery may be attempted in some cases, based on the results of lymphangiography.
Recovery of Lymphedema in Dogs
There is no cure for lymphedema, but if the underlying cause is found and treated, the condition may resolve with treatment. In cases of congenital lymphedema, several forms may be fatal for the dog. Continue to watch your dog for complications or return of the lymphedema and visit your vet as recommended.
Fossum, T.W., King, L.A., Miller, M.W., Butler, L.M. Lymphedema: Clinical Signs, Diagnosis, and Treatment. Journal of Veterinary Internal Medicine, 6,312-319, 1992, doi:10.1111/j.1939-1676.1992.tb00361.x
Fossum, T.W., Miller, M.W. Lymphedema: Etiopathogenesis. Journal of Veterinary Internal Medicine, 6,283-293, 1992, doi:10.1111/j.1939-1676.1992.tb00353.x
Kang, JH., Lee, JY., Mo, IP., Lee, WG., Chang, DW., Na, KJ., Yang, MP. Secondary Malignant Lymphoedema after Mastectomy in Two Dogs. Journal of Small Animal Practice, 48,10,579-83, 2007, doi:10.1111/j.1748-5827.2006.00270.x