What Are Lymph Nodes?
Lymph nodes are small, bean-shaped glands that are part of a dog’s lymphatic system. The lymphatic system is a network of vessels, ducts, and nodes that carries lymph fluid throughout the body. Lymph is a clear fluid that contains white blood cells, which help fight infection and disease.
Lymph nodes act as filters for this fluid. They contain immune cells that trap bacteria, viruses, cancer cells, and other foreign substances. This helps prevent the spread of infection or disease in the body. Lymph nodes are located throughout a dog’s body, clustered in areas such as the neck, armpits, groin, and chest.
Healthy lymph nodes are small, smooth, and firm. When infection occurs, lymph nodes respond by producing more immune cells, causing them to swell. This is a sign that the immune system is active and fighting. Swollen lymph nodes indicate a localized immune response rather than a systemic infection. Monitoring lymph nodes helps identify potential problems and determine if further treatment is needed.
In summary, lymph nodes play a vital role in a dog’s immune health. Checking them regularly and knowing what is normal for your dog can help identify underlying issues before they become more serious.
Locations of Major Dog Lymph Nodes
Dogs have lymph nodes located throughout their body. The major lymph node locations include:
Head and Neck
There are numerous lymph nodes in a dog’s head and neck. Key lymph nodes in this area include the mandibular, parotid, and retropharyngeal lymph nodes. The mandibular lymph nodes are located under the jaw. The parotid lymph nodes are found near the cheeks. The retropharyngeal lymph nodes are positioned at the back of the throat.
Front Legs
The front legs contain the prescapular and axillary lymph nodes. The prescapular lymph nodes are found in the shoulder region near the front legs. The axillary lymph nodes are located in the armpit area.
Hind Legs
Key lymph nodes in the hind legs include the popliteal and inguinal lymph nodes. The popliteal lymph nodes are behind the knee joint. The inguinal lymph nodes are found in the groin area near the hind legs.
Chest
Within the chest, an important lymph node is the mediastinal lymph node located in the center near the heart and lungs.
Abdomen
In the abdomen, there are mesenteric lymph nodes around the intestines and kidney lymph nodes near the kidneys.
Lymph Nodes in the Dog’s Head
There are several important lymph nodes located in a dog’s head and neck region. Three major ones to be aware of are the mandibular, parotid, and retropharyngeal lymph nodes.
The mandibular lymph nodes are located under the jaw, with one node on each side of the head. These filter lymph fluid from the mouth, nose, face, and exterior of the skull. Enlarged mandibular lymph nodes may indicate an issue like an infection in the mouth.
The parotid lymph nodes sit near the back of the jaw, just below each ear. They drain lymph fluid from the exterior ear, eye, and side of the face. Swollen parotid lymph nodes can sometimes be felt under the jaw as small movable lumps.
Finally, the retropharyngeal lymph nodes are found in pairs behind the pharynx, which is located along the back of the throat. These filter lymph from the nasal passages, pharynx, and cranial cavities. Because they reside deeper in the neck, swollen retropharyngeal nodes may go unnoticed unless a veterinarian feels for them during an exam.
Lymph Nodes in the Dog’s Front Legs
The front legs contain several important lymph nodes that owners should be aware of. The main lymph nodes in the front legs include:
Axillary Lymph Nodes
The axillary lymph nodes are located in the armpit region of the front legs. There is one axillary lymph node on each side of the body. These lymph nodes drain lymph fluid from the front legs, chest, and abdomen.
Prescapular Lymph Nodes
The prescapular lymph nodes are located near the shoulder blade on each front leg. There are typically two prescapular lymph nodes on each side. These lymph nodes drain lymph fluid from the skin, muscles, and joints of the front legs and shoulder.
Popliteal Lymph Nodes
The popliteal lymph nodes are located behind the knee joint on each hind leg. There is one popliteal lymph node on each leg. These lymph nodes drain lymph fluid from the skin, muscles, and joints of the rear legs.
Checking these lymph nodes periodically for signs of swelling or enlargement can help identify potential infections, inflammation, or other health issues requiring veterinary attention.
Lymph Nodes in the Dog’s Hind Legs
There are several important lymph nodes located in a dog’s hind legs. The main ones are:
Popliteal Lymph Nodes
The popliteal lymph nodes, also called the popliteal glands, are located behind the knee joint. There is one popliteal lymph node in each hind leg. These bean-shaped nodes drain lymph fluid from the rear legs below the stifle (knee) and filter harmful substances.
Inguinal Lymph Nodes
The inguinal lymph nodes, also known as the groin lymph nodes, are found near the groin area where the hind legs join the abdomen. There are two inguinal lymph nodes, one on each side. These nodes drain lymph fluid from the rear legs and external genitals.
The popliteal and inguinal lymph nodes in the hind legs act as filters for bacteria, viruses, cancer cells, and other harmful substances. Swelling of these lymph nodes may indicate an infection or inflammation in the rear legs.
Lymph Nodes in the Dog’s Chest
The most prominent lymph nodes in a dog’s chest area are the mediastinal and sternal lymph nodes. The mediastinal lymph nodes are a group of nodes located in the space between the lungs, known as the mediastinum. These lymph nodes drain lymph from the lungs, heart, esophagus, and thymus gland.
The sternal lymph nodes refer to the nodes found along each side of the breastbone (sternum). They drain lymph from the front legs, chest, and abdominal wall. The sternal lymph nodes can often be felt just under the skin in healthy dogs, but become enlarged when fighting infection, cancer, or other diseases.
It’s important to monitor the chest lymph nodes and be aware of any unusual swelling, which may indicate an issue needing veterinary attention. During a routine exam, a vet will palpate the prescapular, axillary, and sternal nodes to check for abnormalities.
Lymph Nodes in the Dog’s Abdomen
There are several important lymph nodes located in a dog’s abdomen, including the pancreatic, renal, and mesenteric lymph nodes.
The pancreatic lymph nodes are located alongside the pancreas and help drain lymph fluid from the pancreas. Enlarged pancreatic lymph nodes may indicate inflammation or cancer of the pancreas.
The renal lymph nodes drain lymph fluid from the kidneys and ureters. Swollen renal lymph nodes may signify kidney infection, inflammation, or cancer.
The mesenteric lymph nodes drain lymph fluid from the intestines and abdominal viscera. Enlarged mesenteric lymph nodes can be a sign of intestinal disease, abdominal infection, inflammatory bowel disease, or abdominal cancers.
It’s important to monitor lymph nodes in the abdomen as part of routine wellness exams. Any notable enlargement of these lymph nodes should prompt further investigation and veterinary care.
Signs of Swollen/Enlarged Lymph Nodes
Swollen or enlarged lymph nodes in dogs can cause visible and/or palpable lumps under the skin. Owners may notice round, firm bumps under the skin around areas where lymph nodes are located, like under the jaw, down the legs, and near the shoulders and hips.
In addition to visible/palpable lumps, other signs of swollen lymph nodes in dogs include:
- Lethargy
- Loss of appetite
- Fever
- Weight loss
- Discharge from eyes, nose, or other openings
- Difficulty eating or swallowing
- Enlarged tonsils
- Coughing/breathing issues if chest lymph nodes are enlarged
- Vomiting/diarrhea if intestinal lymph nodes are enlarged
Swollen lymph nodes are usually a sign of infection or inflammation somewhere in the body. Owners should monitor their dog closely and contact their veterinarian if they notice any lumps, bumps, or abnormal symptoms that could indicate enlarged lymph nodes.
Causes of Swollen Lymph Nodes
There are several potential causes of swollen or enlarged lymph nodes in dogs:
Infection
One of the most common causes of swollen lymph nodes in dogs is an infection. Infections that can lead to lymphadenopathy include:
- Bacterial infections like abscesses or cellulitis
- Viral infections like parvovirus, distemper, or rabies
- Fungal infections like valley fever or ringworm
- Parasitic infections like heartworm disease or tick-borne diseases
When the lymph nodes swell in response to an infection, it’s a sign that the immune system is working to filter out infectious organisms and prevent their spread in the body.
Cancer
Lymphoma is one of the most common cancers seen in dogs. It causes a proliferation of abnormal lymphocytes that often leads to swollen lymph nodes. Lymph nodes can also swell due to metastasis of other types of cancer like mammary cancer or melanoma.
Immune Disorders
Autoimmune diseases where the body attacks its own healthy cells and tissues can also lead to swollen lymph nodes. Examples include immune-mediated polyarthritis, systemic lupus erythematosus, and immune-mediated hemolytic anemia.
When to See the Vet
If you notice any swelling in your dog’s lymph nodes, it’s important to have your veterinarian examine them as soon as possible. Here are some guidelines on when lymph node swelling requires prompt veterinary attention:
Significant Size Increase
If a lymph node has doubled or tripled in size compared to normal, you should make an appointment with your vet right away. Even mild swelling that persists for more than a day or two warrants medical attention.
Location Matters
Swollen nodes in certain areas are more concerning than others. Enlarged lymph nodes behind the knees, in the groin area, and under the chin should be evaluated urgently as they can indicate a systemic issue.
Other Symptoms Present
If your dog has swollen lymph nodes along with lethargy, loss of appetite, vomiting, diarrhea, or other concerning symptoms, promptly contact your vet. The lymph node changes could signal an underlying infection or more serious condition.
No Obvious Cause
You should make an appointment if the swollen nodes seem to have arisen for no apparent reason and your dog hasn’t suffered any injuries, bites, etc. Unexplained lymph node swelling could point to an underlying illness.
Persistent Swelling
Lymph nodes that remain swollen and enlarged after a week or two despite home treatment warrant veterinary assessment. Persistent swelling can indicate a chronic condition requiring medical care.
Trust your instincts – if your dog’s lymph nodes look or feel abnormal, or you notice swelling without an obvious cause, contact your vet right away. They can examine your dog and determine if testing or treatment is needed.
