Lymphedema in Dogs - Swollen Limbs

An edema is a term for various types of fluid retention in the tissue of a dog's body. When this fluid accumulates in the subcutaneous tissue of the lymphatic system, we refer to it as a lymphedema. This is due to some type of malfunctioning of the lymphatic system, something we explore further below.

The lymphatic system consists of a network of nodes, lymphatic vessels and lymphoid organs. The latter include the thymus and the spleen. These components work together to collect and transport lymph fluid through various tissues in the body. When this system does not function properly, the lymphatic fluid collects in the tissue under the skin, resulting in the swelling.

Since the lymphatic system extends over their body, the fluid accumulation can be almost anywhere. However, we often see the lymphedema present in areas near the lymph nodes. This is why we see the dog's legs often swell with fluid.

It is also important to note that there are other types of swelling on a dog's legs. Tumors, skin diseases and allergic reactions can cause localized inflammation. However, not all will be swelling due to fluid accumulation, i.e. an edema.

Canine breeds predisposed to lymphedema

In the case of dogs, the most frequently affected areas are the hind limbs. There does not appear to be a predilection for the appearance of the disease according to sex, but breed does appear to play a part. Among the breeds most affected by lymphedema, we can find the

• Bulldog
• German Shepherd
• Labrador Retriever
• Great Dane
• Dachshund

Although it is possible there are other causes of a swollen leg in these breeds, it is good to consider it a possibility. You should relay any additional information to the veterinarian.

Canine lymphedema can be classified into two groups:

• Primary: when it is caused by a primary defect in the lymphatic system itself, specifically in the nodes and/or lymphatic vessels.
  
  
• Secondary: when it appears secondary to other pathological processes or as a result of surgical intervention, trauma, etc.

Now we know the two types of canine lymphedema, we explain the main underlying causes of both these categories:

• Primary lymphedema: is caused by congenital anomalies. Specifically, primary-type lymphedema in dogs can be caused by lymphatic hypoplasia or by lymphatic hyperplasia and dilatation.
  
  
• Secondary lymphedema: secondary lymphedema in dogs can be produced by a range of pathological processes. These include malignant cancers (primary or metastatic), inflammation, trauma, chronic infections, parasitic infestations or immune mediated disease. It can also occur as a result of surgery.

Edemas not only affect the front and back limbs of a dog. They can form in various types of tissue in the body. Learn about a potentially life-threatening swelling of the lungs with our article on pulmonary edema in dogs.

The main clinical sign associated with canine lymphedema is swelling of the affected area. As we have explained, lymphedema in dogs is more frequent in the legs, especially in the hind limbs. However, the forelimbs, abdomen, genital area and ears can also be affected. It can be unilateral if only one side of the body is affected, or bilateral if both sides are affected simultaneously.

As well as legs being swollen with fluid, we may see certain other symptoms which include:

• When it affects the legs, the swelling generally begins in the distal area of the extremity, i.e. the area farthest from the animal's body. As it progresses, it spreads towards the proximal area, i.e. the area closest the body.
  
  
• Pressing the affected tissue firmly with the finger produces a depression (known as a pit) that persists for a few seconds after the finger is removed.
  
  
• The skin of the affected area is usually thinner and spongy in texture.
  
  
• It is usually painless unless there is massive swelling or it is accompanied by cellulite.
  
  
• The area is usually neither hotter nor colder than normal, meaning it maintains the same body temperature of the dog.
  
  
• Regional lymph nodes may not be palpable.
  
  
• The patient may be less active than usual due to the additional weight of the limb. They may also find movement more difficult and you can see the dog limping on their affected leg.

Some of these clinical signs are common with edema caused by abnormalities of the venous system (such as venous stasis), heart failure, renal failure, cirrhosis, or hypoproteinemia. It will be important to differentiate both alterations during the diagnostic process.

Image: researchgate.net

When we see a dog's leg or legs swollen with fluid, we need to take them to a veterinarian. While some may require minimal treatment, others are potentially life threatening. The diagnosis of canine lymphedema is based on the following factors:

• Clinical history and general examination: the clinical signs described in the previous section allow us to guide the diagnosis of canine lymphedema.
  
  
• Laboratory tests: including blood tests, urinalysis and other complementary tests. They are necessary to differentiate between lymphedema and other types of swelling, as well as to identify the cause of secondary type lymphedema.
  
  
• Skin biopsy and histopathology: allows visualizing the microscopic lesions associated with lymphedema. In the case of primary lymphedema, it will allow the detection of the specific type of congenital alteration (hypoplasia or hyperplasia) that causes the lymphedema. Varying degrees of dermal or subdermal edema are commonly seen, with dilated or hyperplastic lymphatic vessels. In chronic cases, it can be accompanied by fibrosis of the tissue. In this case, the swelling won't feel as fluid as before.
  
  
• Direct lymphangiography: consists of a contrast X-ray of the lymph nodes and vessels. To obtain the radiographic image, the water-based contrast medium must be injected into a lymphatic vessel.
  
  
• Magnetic resonance imaging (MRI): can be performed as an advanced imaging test, since it allows us to see the structural changes caused by lymphedema and offers relevant information on the presence, architecture and size of the lymph nodes.

It is not only a dog's limbs that might swell. Take a look at our article on why my dog's eye is swollen to learn about other types of canine inflammation, as well as their causes and treatment.

The success of the treatment of canine lymphedema depends to a great extent on its progress and chronicity. The early stages are generally reversible and resolve spontaneously or with supportive treatment. However, when the process becomes chronic, tissue fibrosis usually occurs, complicating treatment.

We must emphasize that there is no curative treatment for lymphedema in dogs. However, there are various therapeutic options, both medical and surgical, which may help control the process. Next, we collect the main therapeutic alternatives or supportive therapies for canine lymphedema:

• Robert Jones-type compression bandage: it is especially useful in the early stages of lymphedema, as it helps reduce swelling and provides relief to the patient. It is especially useful on the leg swelling.
  
  
• Rigid bandages: with splints and/or plaster.
  
  
• Pharmacological treatment: although there are few studies on the matter, tocopherol nicotinate and sodium sulfonate hydrate may be effective in controlling some clinical signs. Long-term treatment with diuretics (such as furosemide) is contraindicated.
  
  
• Surgical treatment: when conservative treatment is not effective, it is necessary to resort to surgical treatment. Options include removal of edematous tissue, reconstructive surgery, and, in very severe cases, amputation of the affected limb.

In addition, in cases of secondary lymphedema in which the primary disease is known, it is also necessary to establish a specific treatment for said primary cause. For the above reasons, it is essential to go to a veterinary center when the first symptoms are observed, since it is important to find the cause to treat lymphedema in dogs.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

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