Lymphedema refers to a disorder in which fluid accumulates in the space between cells, causing swelling. Depending on its cause and severity, it can be mild or it can be so severe as to be fatal. Learn more about lymphedema in dogs, what causes it, and how it’s treated.

What Is Lymphedema in Dogs?

The body’s lymphatic system works hand-in-hand with its circulatory system, but instead of blood, it pumps lymph. Lymph is a clear fluid that’s essential for several bodily functions, most notably its roles in immunity, waste removal from cells, and replenishing the fluid in the bloodstream.

When blood reaches the tips of its capillaries, some blood plasma seeps through tiny holes in the capillary walls. This plasma, now called lymph, envelopes the surrounding cells and delivers oxygen and nutrients. It also scavenges cell wastes, damaged cells, bacteria, and viruses, as well as extra fluid that the capillaries couldn’t reabsorb.

The lymph then moves into lymphatic capillaries that carry it back through the body, passing through various lymph nodes on the way. The lymph nodes filter out harmful organisms, allowing the lymph to continue its journey until it’s reabsorbed back into the bloodstream.

If something prevents lymph from flowing into the lymphatic capillaries, it builds up in the area surrounding the cells (called the interstitial area). The lymph remains there and can be pushed by gravity to sink lower on the dog’s body, either down the legs or, less often, beneath the torso. It fills up the interstitial area, pushing the cells apart and causing the area to swell. This condition is called lymphedema.

What Causes Lymphedema?

Lymphedema can be primary. In this case, the dog is born with a malformed or poorly functional lymphatic system. Primary lymphedema can be hereditary; in some dogs, it’s been shown to be inherited as a dominant trait.

A 1992 study looked at breeds that may be predisposed to lymphedema, but these reports often only found one dog of that “predisposed” breed. That report did state that possibly Bulldogs had a genetic predisposition, and also reported on a case of dominantly inherited primary lymphedema in a Poodle mix and her offspring, and possibly Old English Sheepdogs.

Lymphedema is more often secondary, caused by injuries, surgery, radiation, or even chemotherapy. Lymph nodes may be removed during some cancer surgeries, or damaged from radiation or accidents. The lymph nodes themselves can be cancerous. When lymph nodes are damaged or missing, lymph tends to not move past them. In humans, microfilariae infections are the main cause of lymphedema throughout the world, but that isn’t the case with dogs.

Fortunately, primary lymphedema isn’t common. In fact, AKC Chief Veterinarian Dr. Jerry Klein says he’s never personally seen a case of primary lymphedema. This could be partly because of its rarity or because few breeders try to treat such puppies because of their poor prognosis. “Usually the ones that I saw were secondary to mass/neoplasia, or in some cases, secondary to mastectomy, radiation therapy, or severe inflammation, such as bee stings,” explains Dr. Klein.

Note that while lymphoma (cancer of the lymph nodes and lymphatic system) may or may not cause lymphedema as a sign, lymphoma shouldn’t be confused with lymphedema. Lymphangioma and lymphangiosarcoma are tumors that develop from the lymphatic vessels or tissues underlying the skin. These, too, can cause lymphedema but are separate conditions.

What Are the Signs of Lymphedema?

In dogs with primary lymphedema (PLE), the disease typically appears within the first few days to months of life. It most commonly first appears as swelling in one or both hind legs. If other parts of the body are affected, it’s usually in conjunction with swelling of the lower legs. The condition can be severe or mild. Note that anasarca (“walrus” or “water” puppies), a condition in which puppies are born with severe swelling throughout their body, is a different, unrelated condition.

It’s possible for dogs with mild localized primary lymphedema to not have signs until much later in life, or in another part of the body, such as with a one-year-old that developed it only on its muzzle.

In dogs with secondary lymphedema, the affected area is generally distal (away from the torso and toward the extremities) to an area of trauma, surgery, or treatment, especially if it involved removing or possibly damaging lymph nodes.

Lymphedema in its early stages has a distinct feel to it. The tissue is soft and mushy, almost like a partially filled water balloon. Pressing on it leaves a depression, or pit, for several seconds. Entire handprints can even remain if the area is large enough. As the condition advances and the area becomes even more fluid-filled, the skin is stretched tightly and no longer pits.

Lymphedema is generally painless, but as it progresses the stretched skin can be painful. In addition, the added weight and odd feeling can cause lameness.

Lymphedema can be confused with other causes of swelling, but has differences:

• Unlike swelling from infections, the area isn’t hot and doesn’t contain pockets of fluid that can be drained.
• Unlike swelling from allergies or insect stings, the area isn’t itchy, doesn’t respond to antihistamines, and doesn’t go away.
• Unlike swelling from snake bites, the area isn’t painful.
• Unlike swelling from ascites or bloat, the affected area is seldom the abdomen.

How Is Lymphedema Diagnosed?

Lymphedema isn’t an emergency, but it’s commonly confused with some conditions that require emergency care. These include bloat, infection, snake bites, and trauma. If you’re unsure what the problem could be, especially if the dog is in pain, feverish, or the affected area is confined to the abdomen, it’s best to err on the side of caution and take your dog to a veterinarian immediately.

Your veterinarian can diagnose lymphedema with several tests. A complete blood count and a blood biochemistry profile will usually be normal in a dog with lymphedema but are done to rule out other causes. The same is true for radiographs and ultrasounds, in the event the veterinarian suspects internal abdominal bleeding, a fracture, or possibly bloat. A heartworm test may be performed to check for microfilariae.

Your veterinarian may suspect primary lymphedema based on your dog’s age and possibly breed, or secondary lymphedema based on your dog’s history or any cancers, traumas, treatments, or surgeries.

A lymphangiography is the definitive test for lymphedema. In it, a contrast substance is injected into the lymphatic system, and then X-rays are taken to follow the now-visible lymph to see if it travels up the limbs or away from the affected area as it should. A recent report outlined the use of computed tomography to visualize the problem in a dog. This tool, along with several others, has previously been used to diagnose the condition in humans.

What Is the Prognosis for Lymphedema?

The prognosis for lymphedema depends on the severity, whether it’s acute or chronic, and whether it’s primary or secondary. While lymphedema will seldom improve, unless it’s due to some other temporary condition, its progress can be slowed or halted.

Puppies with severe primary lymphedema have the worst prognosis. Owners are often advised to humanely euthanize them immediately. Otherwise, they generally have poor quality of life and a severely shortened life span due to multiple infections and organ failure.

Skin and tissue infections are a problem in any case of lymphedema since lymph fluid is rich in protein. When it’s congested within the tissue, it can become a favorable environment for bacteria. The congested area also reduces normal blood flow to the tissue, interfering with wound healing. Preventing infection is a critical job of caring for a dog with lymphedema.

Any swollen area should be kept clean to avoid infections and inspected frequently. Owners must be constantly on the lookout for redness, itchiness, pain, and increased swelling. Because infections can spread rapidly, a dog with lymphedema with the slightest sign of infection should see its veterinarian immediately. Treatment of the infection usually consists of broad-spectrum antibiotics.

Organ failure can occur when lymph fluid accumulates around organs, placing pressure on them, and interfering with their normal function. Thus, caregivers must also be vigilant for signs of any systemic illness and act quickly if they suspect anything.

Caring for a dog with primary lymphedema can be challenging and in the end, heartbreaking, as they tend to have a shortened lifespan unless they receive constant monitoring, and even then, may not survive.

Dogs with mild primary or secondary lymphedema may have a much better prognosis, especially if the lymphedema is limited to just one leg or body part. In these cases, the same precautions against infection remain.

How Is Lymphedema Treated?

Unfortunately, no treatment exists that can cure or significantly improve lymphedema. But there are ways to manage it, with the aim of delaying or stopping its progression. If the lymphedema is caused by another disease, then treatment will be directed to correct that cause first.

Caring for Affected Tissues

Be sure to keep affected tissues clean, and protect the dog from cuts, scrapes, and even insect bites. Clean all cuts with soap and water, and apply an antibacterial ointment. Contact your veterinarian at the first sign of infection. Avoid using heating pads or ice packs, which could do more harm than help.

Mild exercise is considered helpful, as muscle contractions help move lymph and improve drainage. However, avoid overly vigorous exercise or any activity that comes with the risk of cuts or scrapes.

Although difficult to do with a dog, if possible, elevate the affected limb or limbs when resting. This allows gravity to help drain the fluid toward the body. Also, remind your veterinarian to avoid giving injections in affected limbs.

Applying Pressure or Compression

In humans with lymphedema, general massage isn’t considered beneficial. However, some success is attributed to a gentle form of massage called manual lymphatic drainage, which is used to stimulate circulation and push the lymph toward the body. No data exists on its use in dogs.

Multi-layer compression bandages, or Robert-Jones bandages, are used in both dogs and people. These consist of several layers of bandages starting near the toes, and applying various amounts of pressure on the affected leg to move fluid upward. A veterinarian needs to apply these bandages, at least at first. If they’re too tight they could cut off blood supply and cause even more serious problems.

Compression pumps, which inflate and deflate a cuff placed in various areas over the affected limb, are often used for human lymphedema but not for dogs.

Medication

Drug therapy is generally unhelpful. Although diuretics seem like they might help, they’re no longer recommended in human cases because they cause electrolyte imbalances. Steroids are contraindicated because they increase the susceptibility to infection. Currently, benzopyrones have the most evidence of being effective in humans, but their effectiveness hasn’t been adequately supported. There is also no record of their use in treating canine lymphedema. Several studies using mice have shown promising results with either Tacrolimus, hyaluronidase, or Ketoprofen. None of these has yet been proven effective in humans, nor tested at all in dogs.

Changes in Diet

Diet has been investigated in human studies, as obesity makes lymphedema worse in people. It’s generally advised to keep sodium content low since sodium increases fluid retention. Dietary supplements have also been used in humans. Selenium was found to be helpful in people with secondary lymphedema. More recently, hydroxytyrosol (HT), an olive oil extract, has been shown to be helpful for people with lymphedema. Garlive, a supplement containing HT, hesperidin, spermidine, and vitamin A, exhibited promising effects in mice.

Surgery

Surgery is considered a treatment of last resort and is seldom used in dogs with lymphedema. In humans, it can be used to debulk an area of fibrous tissue and transplant lymph nodes. Microsurgery can reconnect lymphatic structures and blood vessels. Amputation is used when no other alternative is available. Surgery would only be an option for dogs that have lymphedema confined to one limb or a restricted area.

Emerging Treatments

A recent research project delivers a drug to help existing lymphatic vessels pump using a nanoparticle. So far, testing with a mouse model has been encouraging. In a study using a dog model in which lymphedema was purposefully created using surgical techniques, the researcher could also use surgical techniques to redirect lymph into a vein, and then apply the same procedure to a human with partial success. But while these advances are promising, the current therapies, even for people, are still often unrewarding. They wouldn’t be available until far in the future for dogs.

In humans, the treatment of choice overall is complete decongestive therapy (CDT). This treatment combines manual lymphatic drainage, multilayered compression bandages, and physical exercises.

Where Can I Find Help for My Dog With Lymphedema?

It’s hard to find physicians specializing in lymphedema for humans. Finding a veterinarian with experience or special interest in canine lymphedema is even more difficult. Your veterinarian or a local veterinary school or specialist practice may have suggestions. Veterinarians specializing in surgery or internal medicine may also have more expertise.

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