The circulatory system is made up of the blood system and the lymphatic system, which interrelate with each other to carry out common functions. While the blood system has been extensively studied throughout history, research on the lymphatic system has always lagged behind. However, there are numerous diseases that affect the lymphatic system of dogs and other pets, one of them being lymphedema.
If you are interested in learning more about lymphedema in dogs, its causes and treatment, join us in the next article on our site, at where we explain the most important aspects of this pathology.
What is lymphedema in dogs?
Canine lymphedema is defined as the accumulation of fluid in the interstitial space, especially at the level of the subcutaneous tissue,due to malfunction of the lymphatic system.
The lymphatic system consists of a network of nodes, lymphatic vessels, and lymphoid organs (such as the thymus, spleen, or bone marrow) that work together to collect and transport lymph through the tissues towards the blood. When the lymph nodes and/or lymphatic vessels of this system do not function properly, there is an accumulation of lymphatic fluid in the subcutaneous tissue that is under the skin, which causes swelling of the tissue affected
Canine breeds predisposed to lymphedema
In the case of dogs, the most frequently affected areas are the hind limbs. Apparently there is no sex predilection for the appearance of the disease, but there is a predilection for race. Among the breeds most affected by this pathological alteration are the bulldog, the German Shepherd, the labrador retriever, the German Bulldog and the dachshund
Types of lymphedema in dogs
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 surgeries.
Causes of lymphedema in dogs
Once we know the two types of canine lymphedema that exist, we will explain what the causes of each are:
- Primary lymphedema: is caused by congenital anomalies. Specifically, primary type lymphedema in dogs can be caused by lymphatic hypoplasia or by lymphatic hyperplasia and dilation.
- Secondary Lymphedema: Secondary lymphedema in dogs can be caused by pathological processessuch as neoplasms (primary or metastatic), inflammations, traumatisms , repeated infections, parasitic infections or immune-mediated disease. It can also occur as a result of surgery.
Symptoms of lymphedema 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 extremities, especially in the posterior ones. However, the forelimbs, abdomen, genital area and ears can also be affected. In addition, it can be unilateral if only one side of the body is affected, or bilateral if both sides are affected simultaneously.
Below, we collect some of the characteristics that can be observed in the affected area:
- When it affects the extremities, the swelling usually begins in the distal area of the extremity (that is, in the area farthest from the trunk of the animal) and, as it progresses, it spreads towards the proximal (the area closest to the trunk of the animal).
- Pressing the affected tissue firmly with your finger causes a sinking(known as pitting) that persists for a few seconds after the finger is removed.
- The skin of the affected area is usually thinner and with a spongy appearance.
- Usually painless unless there is massive swelling or accompanied by cellulite.
- The area is usually neither hotter nor colder than normal.
- Regional lymph nodes may not be palpable.
- The patient may be less active than usual, due to the added weight of the limb.
Some of these clinical signs are common with edema caused by abnormalities of the venous system (such as venous stasis), heart failure, kidney failure, cirrhosis or hypoproteinemia, so it will be important to differentiate both alterations during the diagnostic process.
Diagnosis of lymphedema in dogs
The diagnosis of canine lymphedema is based on the following points:
- Clinical history and general examination: the clinical signs described in the previous section guide the diagnosis of canine lymphedema.
- Laboratory tests: including blood tests, urinalysis and other complementary tests. They are necessary, on the one hand, to differentiate between edema and lymphedema, and on the other hand, to try to identify the cause of secondary type lymphedema.
- Skin biopsy and histopathology: allows visualizing the microscopic lesions associated with lymphedema. In addition, 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 tissue fibrosis.
- 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: it can be performed as an advanced imaging test, since it allows us to appreciate the structural changes caused by lymphedema and provides information relevant to the presence, architecture and size of the lymph nodes.
Treatment of lymphedema in dogs
The success of the treatment of canine lymphedema depends, to a great extent, on its chronicity. The early stages are generally reversible and resolve spontaneously or with supportive treatment. However, when the process becomes chronic, tissue fibrosis usually occurs, which complicates treatment.
First of all, we must emphasize that there is no curative treatment for lymphedema in dogs. However, there are various therapeutic options, both medical and surgical, which, although not always successful, can help control the process. Below, we collect the main therapeutic alternatives 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.
- Rigid bandages: with splints and/or plaster.
- Pharmacological treatment: although there are few studies in this regard, tocopherol nicotinate and sodium sulfonate hydrate seem to be effective in controlling the signs clinical. Long-term treatment with diuretics (such as furosemide) is contraindicated.
- Surgical treatment: When conservative treatment is not effective, surgical treatment is necessary. Options include removal of edematous tissue, reconstructive surgery, and, in very severe cases, amputation of the affected limb.
Furthermore, in cases of secondary lymphedema in which the primary disease causing it is known, it is also necessary to establish a specific treatment for the primary cause.
Because of all the above, 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.
