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Swollen Lymph Nodes in Dogs (Lymphadenopathy)

What Are Swollen Lymph Nodes in Dogs?

Swollen lymph nodes in dogs, also known as lymphadenopathy, signify an immune response within the lymphatic system, an integral part of your dog’s immune system. This system comprises lymph nodes and lymphatic vessels, running parallel to blood vessels, and serves various crucial functions such as transporting white blood cells, eliminating waste materials, and generating antibodies to combat diseases.

Lymph nodes, small bean-shaped organs housing immune cells, enlarge when the body fights off viruses, bacteria, or other diseases triggering an immune reaction. Palpable lymph nodes, those detectable through the skin, are located in specific areas including under the jaw (submandibular), at the front of the shoulders (pre-scapular), in the armpit (axillary), at the groin (inguinal), and just behind the rear legs (popliteal).

During a veterinary examination, your veterinarian assesses the lymph nodes by palpating them for any abnormalities, along with checking for unusual lumps or bumps. Typically, only the submandibular and popliteal lymph nodes are palpable in a healthy dog.

Symptoms and Types

Symptoms of swollen lymph nodes in dogs may sometimes be noticed by pet owners at home. When petting your dog, if you come across a new or unusual bump in any of the areas mentioned earlier, it could indicate a swollen lymph node.

Typically, there are no evident symptoms accompanying mildly enlarged lymph nodes in dogs. However, if the lymph nodes are considerably swollen, including those within the thorax and abdomen, you should observe for the following symptoms:

  • Vomiting
  • Coughing
  • Lethargy
  • Fever
  • Poor appetite
  • Enlarged abdomen


The enlargement of lymph nodes in dogs typically occurs when the immune system is activated, often in response to a disease process. If only one or two lymph nodes are swollen, it usually indicates a localized disease. For instance, an infected toe could lead to swollen lymph nodes draining that specific area.

A systemic infection, affecting the entire body, often results in many or all lymph nodes becoming enlarged. Examples of such infections include:

  • Demodectic mange
  • Puppy “strangles” (juvenile cellulitis)
  • Tick-borne diseases (e.g., Lyme disease, ehrlichiosis)
  • Bacterial infections (e.g., Yersinia pestis, which causes canine plague)
  • Reactive hyperplasia (indicating an active immune response)
  • Fungal infections (e.g., Coccidioidomycosis)
  • Immune-mediated diseases (e.g., pemphigus)
  • Cancer (e.g., lymphosarcoma)

Dog Breeds Prone to Swollen Lymph Nodes

Specific dog breeds aren’t inherently prone to swollen lymph nodes. However, certain breeds may be predisposed to diseases that result in swollen lymph nodes. Additionally, some breeds have a higher likelihood of developing lymphosarcoma, a cancer affecting the lymphatic system. Examples of such breeds include Golden Retrievers, Boxers, Dobermans, Rottweilers, among others.

Toy breeds like Yorkies, Poodles, and Dachshunds are notably susceptible to dental diseases, often presenting with enlarged submandibular lymph nodes when they suffer from infected teeth and gums.

In most instances, a dog’s lifestyle serves as a better indicator of susceptibility to diseases causing swollen lymph nodes. For instance, hunting dogs or those spending ample time outdoors are at higher risk of contracting tick-borne diseases such as Lyme disease and ehrlichiosis, as well as fungal, bacterial, or parasitic infections that can lead to swollen lymph nodes.

How Vets Diagnose Swollen Lymph Nodes

Identifying swollen lymph nodes is usually evident during a physical examination by the veterinarian. Upon detecting swollen lymph nodes, they may opt to collect a sample using one of the following methods:

Fine Needle Aspirate (FNA): This procedure involves using a syringe and needle to gather cells from the swollen lymph node. These cells are then examined under a microscope by the veterinarian. Alternatively, the sample might be sent to an external laboratory for analysis.

Biopsy: Instead of FNA, the veterinarian may choose to perform a biopsy under general anesthesia. During this procedure, a larger piece of the lymph tissue is removed for analysis by a histopathologist. Typically, the histopathologist’s diagnosis becomes available within 7-10 days.


The treatment for swollen lymph nodes varies based on the underlying cause. In some cases, your veterinarian may initiate treatment for your dog even before receiving a confirmed diagnosis from histopathology. This decision is typically made when the veterinarian is confident about the diagnosis. Treatment options may encompass:

  • Antibiotics
  • Antifungals
  • Anti-inflammatories
  • Steroids
  • Surgery

If cancer is confirmed, chemotherapy may be initiated as part of the treatment plan.

Recovery and Management

The recovery and management of swollen lymph nodes hinge upon the underlying cause. If lymphosarcoma, or cancer of the lymph system, is diagnosed, treatment may involve steroids and chemotherapy. However, this disease typically recurs after remission.

Tick-borne illnesses can often be managed with one round of antibiotics, but there is a possibility of symptoms recurring. It’s crucial to diligently monitor your dog for signs of recurring illness or swollen lymph nodes. If you observe new swelling in your dog’s lymph nodes, promptly contact your veterinarian.

Swollen Lymph Nodes in Dogs (Lymphadenopathy) FAQs

What are the causes of swollen lymph nodes in dogs?

  • Tick-borne diseases: Ensure your dog is protected against ticks with an effective tick control product recommended by your vet, considering your dog’s medical history.
  • Foreign bodies such as plant awns in feet: Prevent your dog from wandering off-leash, especially in areas with longer grass.
  • Fungal and bacterial diseases: Avoid letting your dog roam unleashed to minimize exposure to fungal and bacterial diseases.
  • Cancer (lymphosarcoma): Monitor your dog’s lymph node size regularly and report any abnormal swellings to your vet promptly, especially if your dog is a high-risk breed like Golden Retrievers, Boxers, Dobermans, or Rottweilers.
  • Immune-mediated diseases like pemphigus.

What do swollen lymph nodes in dogs feel like?

Swollen lymph nodes feel like grapes just beneath the skin surface. With diseases like lymphosarcoma, they can double in size overnight.

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