Swollen Submandibular Lymph Nodes in Dogs. What You Need to Know

Anatomy

The submandibular lymph nodes are located beneath the mandible or jawbone, medial to the body and posterior border of the submandibular salivary glands (StatPearls, 2021). There are usually two submandibular lymph nodes on each side of the jaw. They are bean-shaped and measure approximately 1-2 cm. The nodes drain lymph from the nearby tissues including the anterior floor of the oral cavity, lips, cheeks, nasal cavity, sublingual glands, submandibular glands, and anterior teeth (Healthline).

The main function of the submandibular lymph nodes is to filter lymph drained from the head and neck region before passing it on to the deep cervical lymph nodes. This helps remove pathogens and other foreign material. As part of the lymphatic system, the nodes also contain lymphocytes that can mount an immune response against infections (Healthline).

Diseases

diseases causing swollen submandibular lymph nodes

Some common diseases that can cause submandibular lymphadenopathy include:

Lymphadenitis – This is inflammation of the lymph nodes, often caused by an infection. Symptoms include enlarged, tender lymph nodes. It’s diagnosed through physical exam and sometimes imaging tests like ultrasound or CT scan. Treatment involves antibiotics if it’s caused by bacteria.

Lymphoma – Lymphomas are cancers involving the lymphatic system. Submandibular lymphadenopathy can be one of the first signs of lymphoma. Additional symptoms may include fatigue, fever, night sweats, and weight loss. It’s diagnosed through biopsy of the lymph node. Treatment depends on the type of lymphoma but may include chemotherapy, radiation, immunotherapy, or stem cell transplant.

Sialadenitis – This is inflammation of the salivary glands. It leads to swollen, painful submandibular glands. It’s often caused by blockage of the salivary ducts from stones. Diagnosis is through physical exam, lab tests, and sometimes imaging. Treatment involves addressing the underlying cause, warm compresses, massage, hydration, and sometimes antibiotics.

Abscess – A bacterial infection can cause an abscess or pocket of pus to form within the lymph nodes. Symptoms include enlarged, painful nodes and fever. It’s diagnosed through physical exam and sometimes ultrasound. Treatment involves draining the abscess and antibiotics.

Lymphadenopathy

causes of submandibular lymphadenopathy in dogs

Lymphadenopathy refers to enlarged or swollen lymph nodes. The most common causes of submandibular lymphadenopathy in dogs include:

  • Infection – Bacterial, viral, fungal or protozoal infections can cause lymph nodes to enlarge as they trap invading pathogens. Common infections leading to submandibular lymphadenopathy in dogs include toxoplasmosis, leishmaniosis, bartonellosis and lymphocytic plasmacytic stomatitis. [1]
  • Cancer – Lymphoma is one of the most common cancers leading to submandibular lymphadenopathy in dogs. The lymph nodes enlarge due to proliferation of cancerous lymphocytes. [2]
  • Inflammation – Inflammatory conditions like sialadenitis or autoimmune disorders can cause reactive hyperplasia and enlargement of submandibular lymph nodes.

Other less common causes include abscesses, cysts, vascular disorders, trauma etc. Diagnosis involves palpation, fine needle aspiration or biopsy of the enlarged lymph node. Treatment depends on the underlying cause, but may include antibiotics, chemotherapy or surgical removal in severe cases.

Lymphoma

lymphoma involving submandibular lymph nodes

Lymphoma involving the submandibular lymph nodes is rare, accounting for less than 5% of all lymphomas 1. However, the incidence has been increasing in recent years2. The most common types of lymphoma to affect the submandibular lymph nodes are:

  • Follicular B-cell lymphoma
  • Marginal zone B-cell lymphoma
  • Diffuse large B-cell lymphoma

Lymphoma is staged based on the extent of spread. Stages I and II indicate more localized disease, while stages III and IV indicate more advanced disease that has spread to multiple lymph nodes or organs. Prognosis depends on the type and stage of lymphoma. In general, follicular lymphomas have a more indolent course with a 5-year survival over 70%, while diffuse large B-cell lymphoma is more aggressive with a 5-year survival around 50-60%1.

Abscesses

submandibular lymph node abscesses in dogs

Abscesses in the submandibular lymph nodes are typically caused by bacterial infections. Common culprits include Staphylococcus, Streptococcus, and anaerobic bacteria originating from the mouth. Infections can occur due to dental disease, injuries, or foreign bodies in the oral cavity. Abscesses may also form due to the spread of infection from surrounding tissues such as the salivary glands.

Symptoms of a submandibular lymph node abscess include swelling, redness, heat, pain and tenderness in the area under the jaw. The skin may appear shiny. Fever, difficulty swallowing and opening the mouth may occur. There may be a purulent, smelly discharge from the lymph node.

Treatment involves antibiotics to fight the infection. The abscess may need to be lanced and drained by a veterinarian. Dental disease, if present, also needs to be addressed. In severe cases the affected lymph node may need to be removed surgically. Prognosis with appropriate treatment is generally good.

Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078004/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7021150/

Biopsy

A lymph node biopsy is a procedure to remove part or all of an enlarged lymph node for examination under a microscope. This helps determine if the enlargement is due to a benign process like an infection or a malignant process like lymphoma. There are two main types of biopsy – fine needle aspiration (FNA) and surgical excisional biopsy.

In an FNA biopsy, a thin needle is inserted into the lymph node to extract cells that are examined under a microscope. This is a minimally invasive procedure done with local anesthesia. According to Mount Sinai, FNA biopsy is about 80-90% accurate in detecting cancer.

In an excisional biopsy, the entire lymph node or part of it is surgically removed through an incision. This is done under general anesthesia. The lymph node is then sent to a lab for microscopic examination, culture, and sensitivity. According to Saint Luke’s Health System, results may take a few days to a week.

Potential risks of lymph node biopsy include infection, bleeding, nerve injury, hematoma, seroma, and lymphedema. Patients may experience mild pain, swelling, and bruising afterwards.

Fine Needle Aspiration

Fine needle aspiration (FNA) is a minimally invasive procedure used to evaluate enlarged submandibular lymph nodes in dogs. It involves using a small needle and syringe to extract cells from the lymph node for cytological evaluation.

The procedure is performed with the dog under brief sedation or local anesthesia. The lymph node is stabilized between the fingers and a small needle (usually 22-25 gauge) is inserted into the node. Gentle suction is applied with an attached syringe as the needle is moved back and forth within the node. This collects loose cells for cytological analysis. Pressure is applied after removing the needle to prevent bleeding.

Cytology from FNA allows for evaluation of lymph node architecture and inflammatory or neoplastic changes. It is an inexpensive and quick diagnostic tool. However, it has limitations in obtaining representative samples, determining lymphoma subtype, and evaluating lymph node metastasis. Most enlarged submandibular lymph nodes will require excisional biopsy for definitive diagnosis. FNA is useful for an initial screening and determining next diagnostic steps [1].

Removal

The submandibular glands may need to be removed for several reasons, including cancer, obstruction from stones, or chronic inflammation [1]. Removal of the submandibular gland is called a submandibulectomy.

During the procedure, an incision is made under the jawline and the gland is carefully dissected away [2]. Care is taken to avoid damage to surrounding structures like the facial nerve. Lymph nodes may also be removed depending on the diagnosis. Once the gland is fully removed, the incision is closed with sutures.

Recovery time after submandibulectomy is usually 1-2 weeks. There may be swelling, bruising, and stiffness around the jaw. Pain can be managed with medication. Most people are able to return to normal activities after 2 weeks. Dry mouth is a common side effect since saliva production is reduced.

Imaging

Imaging techniques like radiography, ultrasound, CT, and MRI can be useful for evaluating the submandibular lymph nodes in dogs. On radiographs, the submandibular lymph nodes appear as soft tissue opacities in the ventral neck. Ultrasound allows assessment of lymph node size, shape, margins and internal architecture. The normal submandibular lymph node has an elongated shape with a hypoechoic cortex and hyperechoic medulla on ultrasound. CT provides excellent anatomic detail and is considered the modality of choice for evaluating cervical lymph nodes in dogs (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8697330/). MRI also reliably depicts the normal anatomy of canine cervical lymph nodes, which appear isointense to muscles on T1-weighted images and hyperintense on T2-weighted images (https://pubmed.ncbi.nlm.nih.gov/17153061/).

Prognosis

The prognosis for swollen submandibular lymph nodes in dogs depends on the underlying cause. Some key factors that determine prognosis include:

https://www.kingsdale.com/causes-of-swollen-lymph-nodes-in-dogs

  • Infections – With prompt treatment such as antibiotics, the prognosis for infection-related lymphadenopathy is often good.
  • Cancer – Lymphoma carries a grave prognosis with average survival times of 6-12 months. However, some forms may respond better to chemotherapy.
  • Benign masses – Surgical removal may fully resolve benign masses. Clean margins are important.

Treatment options depend on the cause but may include:

https://www.petmd.com/dog/conditions/cancer/c_multi_lymphadenopathy

  • Antibiotics for infections
  • Anti-inflammatories for inflammation
  • Chemotherapy drugs for lymphoma
  • Surgery to remove benign masses
  • Drainage and flushing of abscesses

Regular monitoring and follow-up care is important regardless of cause. Overall prognosis ranges from good to poor depending on diagnosis and how early treatment begins.

Scroll to Top