Swollen Lymph Nodes In Dogs: Key Causes, Diagnosis & Treatment

Spot early health changes through attentive care to support your pet’s comfort.

By Anjali Sayee

Created on Aug 28, 2025

Spot early health changes through attentive care to support your pet’s comfort.

Swollen Lymph Nodes in Dogs: Causes, Diagnosis, and Treatment

Lymph nodes play a crucial role in your dogâs immune system, acting as filters for foreign particles and as a hub for immune cell activity. Swollen lymph nodes, medically termed lymphadenopathy, can be a sign your dogâs body is fighting infection, responding to inflammation, or potentially dealing with more serious health concerns such as cancer. Understanding what swollen lymph nodes mean and knowing how to respond can help you safeguard your petâs health and well-being.

What Are Lymph Nodes?

Lymph nodes are small, bean-shaped structures distributed throughout your dogâs body as part of the lymphatic system. They contain lymphocytes and other immune cells that help the body recognize and fight infections and other diseases. Common lymph node locations in dogs include:

Submandibular: Underneath the jaw
Prescapular: In front of the shoulders
Axillary: In the armpits
Inguinal: In the groin
Popliteal: Behind the knees

Normally, lymph nodes are so small they are difficult to feel. When enlarged, they may become palpable or visibly swollen, signaling an abnormal immune response.

Functions of Lymph Nodes in Dogs

The primary functions of lymph nodes are to:

Filter out and destroy bacteria, viruses, and abnormal cells.
Produce and house lymphocytes (white blood cells) that fight infection.
Help regulate immune system response.

Because of these functions, lymph nodes react and swell when encountering diseases, infections, or other health threats.

Causes of Swollen Lymph Nodes in Dogs

There are several reasons why a dog’s lymph nodes may become enlarged. The following table summarizes the common causes:

Cause	Description	Common Symptoms
Infections	Bacterial, viral, fungal, or parasitic infections trigger the lymph nodes to enlarge as they filter pathogens.	Fever, lethargy, reduced appetite, localized pain, coughing, sneezing, or discharge.
Cancer (Lymphoma or Metastasis)	Malignant diseases such as lymphoma often cause generalized or localized lymph node swelling.	Persistent swelling, weight loss, fever, decreased activity, other systemic signs.
Immune System Disorders	Autoimmune diseases and allergic reactions may induce lymph node enlargement.	Itching, rashes, joint pain, waxing and waning symptoms.
Local Inflammation	Dental disease, ear infections, or skin wounds can cause nearby lymph nodes to react.	Swelling near jaw, ears, neck, pustules or abscesses, bad breath.
Physical Trauma	Bruising or injury near a lymph node region may lead to swelling.	Localized pain, swelling, sometimes redness or heat.

Recognizing Symptoms of Swollen Lymph Nodes in Dogs

Lymph node enlargement might be the only noticeable symptom, but dogs often display other signs depending on the underlying cause:

Visible lumps: Especially under the jaw, in front of the shoulders, or behind the knees.
Pain or discomfort: Dogs may be sensitive or reactive when lymph nodes are touched.
Lethargy or weakness: Decreased interest in play, walks, or food.
Fever or shivering: Systemic infection can result in an elevated temperature or chills.
Decreased appetite: Dogs may refuse to eat or drink as they feel unwell.
Coughing or respiratory issues: Enlarged lymph nodes in the chest or throat can cause these symptoms.
Gastrointestinal symptoms: Vomiting, nausea, or abdominal swelling.
Behavioral changes: Irritability, withdrawal, or snapping behavior.

If you notice any of these signs in your petâor simply detect an unusual lumpâitâs crucial to have your dog examined by a veterinarian as soon as possible.

Diagnostic Procedures for Swollen Lymph Nodes in Dogs

Since swollen lymph nodes are a symptom rather than a diagnosis, your vet will perform several steps to determine the underlying cause:

Physical Examination: The vet will palpate lymph nodes and check for other signs of disease.
Medical History: Gathering information about recent illnesses, travel, vaccinations, and exposure to other animals.
Fine Needle Aspiration (FNA): A small needle is used to extract cells from the lymph node for microscopic evaluation.
Biopsy: In some cases, surgical removal of lymph node tissue is required for accurate diagnosis.
Blood Tests: Assess organ function, detect infection, inflammation, and blood cell abnormalities.
Imaging Studies: X-rays, ultrasound, or CT scans help detect internal swelling, masses, or systemic involvement.
Urinalysis and other lab work: Depending on symptoms, further testing may be ordered.

These methods provide valuable information to distinguish between benign conditions and more critical issues such as cancer or systemic infection.

Common Disorders Associated with Swollen Lymph Nodes in Dogs

Lymphoma (Canine Lymphosarcoma): A common canine cancer presenting as rapidly enlarged, firm, and non-painful lymph nodes.
Bacterial and Fungal Infections: Such as Streptococcus, Staphylococcus, or Blastomycosis can result in local or generalized lymphadenopathy.
Parasitic Infections: E.g., with ticks or roundworms, either directly affecting the lymphatic system or causing a strong immune response.
Localized Infections/Abscesses: Ear, mouth, skin, or respiratory infections may affect adjacent nodes.
Immune-mediated Conditions: Such as lupus or autoimmune hemolytic anemia.
Allergic Reaction: Sometimes severe allergic encounters can result in localized swelling and node enlargement.

Treatment Options for Swollen Lymph Nodes in Dogs

Effective treatment of swollen lymph nodes always depends on the underlying cause established by your veterinarian:

Antibiotics: Used for bacterial infections. Course and duration depend on the infectionâs nature and severity.
Antifungal or Antiparasitic Medications: Given for fungal or parasitic causes, respectively, as determined by testing.
Anti-inflammatory Drugs: These help manage pain or inflammation, particularly in cases with discomfort.
Chemotherapy: The standard treatment for lymphoma and many metastatic cancers.
Surgery: Surgical removal of the tumor or affected lymph node if localized cancer or abscess is diagnosed.
Supportive Care: Includes fluids, nutritional support, and medications to treat symptoms (e.g., pain, nausea).
Lifestyle Adjustments: Rest, reduced activity, isolation during infectious periods, and careful observation.

Always follow your veterinarianâs treatment plan rigorously, as even mild infections can worsen without proper management, and serious health threats require prompt, specialized intervention.

Home Care and Comfort Measures

Ensure your dog has plenty of rest and minimize stressors.
Keep your pet well-hydrated and maintain a gentle, nutritious diet.
Limit exposure to other dogs or environments (like dog parks or kennels) if infection is suspected.
Administer prescribed medications as directed and monitor for side effects.
Observe for worsening symptoms and contact your vet with any changes.

There are no effective home remedies for treating underlying causes of swollen lymph nodes. Symptomatic relief and supportive care should always go hand-in-hand with veterinary guidance.

Preventing Swollen Lymph Nodes in Dogs

While not all cases can be prevented, certain measures help decrease the risk of lymph node swelling in your dog:

Keep vaccinations up to date: Timely vaccination reduces the risk of infectious diseases.
Provide a balanced diet: Nutrition supports an effective immune response.
Routine vet checkups: Early detection of illness or abnormalities.
Limit exposure to infectious environments: Avoid crowded dog parks, boarding facilities, and grooming salons if disease outbreaks are reported.
Good hygiene: Regular bathing, grooming, and dental care lower the chance of localized infections.
Monitor for trauma: Prevent injuries and address wounds promptly to avoid complications.

Some dogs are more susceptible to reactive lymph nodesâdiscuss any concerns about your petâs immune health or vaccination schedule directly with your veterinarian.

When to See a Veterinarian

If you feel or see a lump where there wasnât one before.
If your dog has persistent or recurrent swelling of lymph nodes.
Sudden signs of pain, fever, lethargy, inappetence, or other systemic illness.
Unexplained weight loss, difficulty breathing, coughing, or visible discomfort.
After physical trauma or suspected insect/animal bite.

Early assessment is essential: timely diagnosis and intervention lead to much better health outcomes for your dog and can help prevent chronic complications.

Frequently Asked Questions About Swollen Lymph Nodes in Dogs

What do swollen lymph nodes feel like in dogs?: Lymph nodes can feel like round or oval, firm lumps under the skin. They may be moveable and painless, but can sometimes cause discomfort if severely swollen or inflamed.
Can swollen lymph nodes mean cancer?: Enlarged lymph nodes can be a sign of lymphoma or metastatic cancer, but they can also result from infections, inflammation, or immune responses. Only a veterinarian can confirm the underlying cause with proper tests.
Is it an emergency if my dog has swollen lymph nodes?: While not all cases require immediate emergency care, swollen lymph nodes should be evaluated by a veterinarian without delay to rule out serious conditions and ensure prompt treatment.
Can I treat swollen lymph nodes at home?: No. While you can make your pet comfortable and follow supportive care advice, the actual cause requires diagnosis and specific treatment from a veterinarian.
How can I help prevent infection-related lymph node swelling?: Maintaining up-to-date vaccinations, regular vet visits, good hygiene practices, and keeping your dog away from unknown or sick animals can help reduce infectious risks.

Key Points to Remember

Swollen lymph nodes are a sign of an underlying health issue, not a disease by themselves.
Infections, cancer, immune disorders, and trauma are some potential causes.
Veterinary diagnosticsâincluding aspiration, biopsy, and blood workâare essential for proper treatment.
Follow all veterinary recommendations for medications, care, and follow-up visits.
Timely intervention often leads to much better outcomes for your beloved canine companion.

References

Author

Anjali Sayee

Anjali is an Associate Editor at StyleCraze with 7 years of experience specializing in hairstyles, hair care, and skin care. She has authored over 300 articles and offers expert advice on hair styling techniques, effective skin care routines, and tips for maintaining healthy hair and skin.

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