Introduction
Lymph nodes are small glands that are part of the lymphatic system, which is a network of tissues and organs that help rid the body of toxins, waste and other unwanted materials. The lymph nodes act as filters along the lymphatic system.
In dogs, lymph nodes can become swollen (enlarged) for many reasons, most commonly due to infection or cancer. Swollen lymph nodes are the body’s way of fighting an infection or disease and are not always cause for concern. However, it’s still important to determine the cause and treat accordingly, as some conditions, like lymphoma, can be serious.
Causes of Swollen Lymph Nodes
While cancer is a concern when lymph nodes are swollen, there are many other common causes of lymph node enlargement in dogs. Some of the main non-cancerous causes of swollen lymph nodes include:
- Bacterial infections – Bacteria like Staphylococcus, Streptococcus, and Bartonella can infect the lymph nodes causing them to swell as the dog’s immune system responds. Lymphadenitis is a condition where the lymph nodes themselves become infected and inflamed.
- Viral infections – Viruses like parvovirus, herpesvirus, rabies virus, and canine distemper virus can infect the lymph nodes and lead to enlargement.
- Fungal infections – Systemic mycoses like blastomycosis, histoplasmosis, and cryptococcosis can spread to the lymph nodes and cause inflammation.
- Parasitic infections – Parasites like ticks, heartworms, and Leishmania can be filtered by the lymph nodes as the immune system responds, causing swelling.
- Immune-mediated diseases – Autoimmune diseases like lupus and immune-mediated polyarthritis can cause generalized lymph node enlargement.
- Injuries and inflammation – Trauma, wounds, abscesses, and other inflammatory conditions near lymph nodes can cause enlargement as immune activity increases.
While scary, swollen lymph nodes from infections and immune diseases are generally manageable with proper veterinary treatment. Only a small percentage of cases are linked to cancers like lymphoma, so it’s important not to assume the worst before getting a diagnosis.
Signs of Swollen Lymph Nodes
Some of the most common signs of swollen lymph nodes in dogs include:
- Lumps or masses under the skin, especially around the neck, legs, or jaw
- Swelling and discomfort around lymph nodes
- Reluctance to turn head or difficulty swallowing due to swollen throat lymph nodes (https://www.imprimedicine.com/blog/lymph-nodes)
- Loss of appetite
- Lethargy
- Fever
- Enlarged abdomen due to swollen internal lymph nodes (https://www.petmd.com/dog/conditions/cancer/c_multi_lymphadenopathy)
- Bad breath in cases of swollen throat lymph nodes
Swollen lymph nodes are usually visible as distinct lumps under the skin around key areas where lymph nodes are concentrated. The lymph nodes in the neck and jaw are most easily detected. Lymph node swelling may range from mild to severe based on the underlying cause. Discomfort, stiffness, and pain can occur when lymph nodes are inflamed.
Diagnosing the Cause
Veterinarians will perform a thorough physical exam to diagnose the cause of swollen lymph nodes in dogs. They will visually inspect and palpate the lymph nodes, feeling for abnormalities in size, shape, and texture. Swollen lymph nodes are often firm and rubbery. The vet will look for asymmetry, with one side being more enlarged than the other. They may take a needle aspirate or biopsy of the lymph node to examine the cells under a microscope. This can help determine if swelling is due to infection, inflammation, or cancer.
In addition to a physical exam, the vet may run blood tests to look for signs of infection or inflammation. A complete blood count can detect an elevated white blood cell count, indicating the body’s immune response. Biochemical tests assess organ function for clues to systemic disease.
Specific blood tests can identify some cancers, such as leukemia, that directly affect the blood. Testing for tick-borne diseases like Lyme disease may be warranted also. Chest x-rays allow visualization of the lymph nodes around the heart and lungs. Abdominal ultrasound allows inspection of lymph nodes deep inside the body cavity.
While most lymph node biopsies require sedation or anesthesia, fine needle aspirates can often be performed with local anesthesia. Examining lymph node cells microscopically provides the most definitive diagnosis. Cancerous cells may have unusual shapes, sizes, and staining patterns. Infectious organisms like bacteria or fungi may be identified. Inflammation is evident based on the types and amounts of white blood cells present. With insight from physical exam findings, bloodwork, and lymph node aspiration or biopsy, vets can determine the root cause of lymphadenopathy.
Sources:
https://www.petmd.com/dog/conditions/cancer/c_multi_lymphadenopathy
https://wagwalking.com/condition/lymph-node-inflammation-lymphadenopathy
Treating Infections
Antibiotics can be used to treat swollen lymph nodes caused by bacterial infections. According to https://wagwalking.com/condition/lymph-node-inflammation-lymphadenopathy, the vet may prescribe antibiotics like amoxicillin or doxycycline for 2-3 weeks. For fungal infections like blastomycosis, antifungal medication such as itraconazole may be prescribed, as noted on https://www.petmd.com/dog/conditions/cancer/c_multi_lymphadenopathy. Viral infections like canine distemper have no direct treatment, so vets focus on supportive care to let the immune system fight it off.
In addition to medication, warm compresses can help reduce swelling and discomfort associated with lymph node infections. Keeping the area clean and preventing irritants or trauma can also aid healing. Though antibiotics treat the infection itself, the lymph nodes may remain enlarged for some time after. Close follow up with the vet is important to ensure the infection has fully resolved.
Managing Immune Diseases
Some autoimmune diseases like lupus and rheumatoid arthritis can cause swollen lymph nodes in dogs. These diseases happen when the immune system mistakenly attacks the body’s own healthy cells and tissues.
There is no cure for autoimmune diseases, so treatment focuses on managing symptoms and reducing flare-ups. The main medications used are immunosuppressants like prednisone, which calm down the overactive immune response. Non-steroidal anti-inflammatory drugs (NSAIDs) may also be used to reduce inflammation and relieve pain.
In addition to medication, lifestyle changes can help dogs with autoimmune diseases. Getting adequate rest, avoiding stressors, and using ramps to prevent joint strain are some steps owners can take. Special diets may also be recommended to avoid triggering flare-ups. With proper management, most dogs with autoimmune diseases can enjoy a good quality of life.
While swollen lymph nodes caused by an overactive immune system can be worrying, they are manageable with immunosuppressants from the vet and lifestyle adjustments. Monitoring symptoms and regular checkups are key to successfully treating autoimmune diseases long-term.
Recovery Time
The recovery time for swollen lymph nodes in dogs depends on the underlying cause:
For swollen lymph nodes caused by bacterial or viral infections, recovery time is typically 1-3 weeks with prompt treatment such as antibiotics or antivirals. The nodes should return to normal size once the infection clears.
With tick-borne illnesses like Lyme disease, recovery can take 4-6 weeks with appropriate medications. Close monitoring is important to ensure the infection is fully treated.
Fungal infections may require 6-8 weeks of anti-fungal medications for the lymph nodes to return to normal.
If the cause is an immune-mediated disease like lymphoma, recovery depends on the treatment plan. Chemotherapy protocols usually last 16-24 weeks. With treatment, lymph nodes may return to normal temporarily but can become enlarged again over time.
For idiopathic lymphadenopathy with no obvious cause, steroids may help reduce swelling but lymph nodes may wax and wane indefinitely.
In most cases of swollen lymph nodes, full recovery takes weeks to months. Seeing gradual reduction in lymph node size is a positive sign. If nodes remain enlarged or continue to grow, further diagnostics are warranted.
Prevention
There are some steps you can take to help prevent infections and injuries that could lead to swollen lymph nodes in dogs:
Maintain good dental hygiene – Brushing your dog’s teeth regularly can help prevent oral infections that may spread to the lymph nodes. Annual dental cleanings by a veterinarian are also recommended.
Avoid wounds and injuries – Be mindful of sharp objects, thorns, and rough play that could cause cuts, punctures or other wounds where bacteria could enter. Keep your dog’s nails trimmed to avoid scratches.
Use flea, tick and heartworm prevention – Parasites can transmit infections that cause lymph node swelling. Use monthly preventatives prescribed by your vet.
Vaccinate your dog – Keeping your dog up-to-date on core vaccines can help prevent infections from distemper, parvovirus and other viruses that affect the lymph nodes.
Feed a nutritious diet – A diet rich in vitamins and nutrients supports your dog’s immune system to help fight off infections.
Avoid toxins and chemicals – Limit your dog’s exposure to toxins, chemicals and plants that could cause an immune reaction.
Reduce stress – Find ways to minimize stressful situations that could weaken your dog’s immune defenses.
Have a vet exam twice yearly – Wellness visits allow early detection and treatment of infections before lymph nodes are impacted.
When to See a Vet
It’s recommended to take your dog to the vet if the swollen lymph nodes persist for more than 2-4 weeks without shrinking. According to petMD, prolonged enlargement of the lymph nodes often indicates an underlying disease that requires veterinary attention.
You should also see the vet right away if your dog has swollen lymph nodes along with concerning symptoms like lethargy, loss of appetite, weight loss, coughing, or difficulty breathing. These signs can point to a more serious health problem that needs prompt diagnosis and treatment.
Seeking timely veterinary care is crucial, as some of the potential causes of swollen lymph nodes like infections, immune disorders, or even cancer can worsen if left untreated. The vet will run tests like bloodwork, imaging, biopsies or fine needle aspirates of the lymph nodes to determine the cause and devise an appropriate treatment plan.
In summary, schedule a vet visit if your dog’s swollen lymph nodes persist beyond 2-4 weeks or are accompanied by other concerning symptoms. The vet can then conduct the necessary diagnostic tests and provide the proper care to manage your dog’s condition.
Conclusion
In most cases, swollen lymph nodes in dogs are not cause for major concern. They are simply the body’s way of fighting off infection or inflammation. With proper diagnosis and treatment from your veterinarian, most causes of canine swollen lymph nodes will resolve on their own over the course of a few weeks. Remember to monitor your dog for signs like lethargy, loss of appetite, and difficulty breathing, as these can indicate a more serious issue. But in general, try not to worry too much about mildly enlarged lymph nodes in an otherwise healthy pup. Just focus on allowing your dog’s immune system to do its job and return to normal function. With some rest and TLC, your furry friend’s swollen lymph nodes should be back to normal size before you know it.