Yes, dogs get swollen lymph nodes, and it’s one of the more common reasons owners bring their dog to the vet after noticing a new lump. The swelling can be caused by something as routine as a local infection or as serious as cancer. Understanding where to find your dog’s lymph nodes, what makes them swell, and which signs warrant urgency can help you act quickly when it matters.
Where to Find Your Dog’s Lymph Nodes
Dogs have dozens of lymph nodes throughout their body, but only a few sit close enough to the surface for you to feel. The three most reliably palpable locations are the mandibular nodes (tucked under the jawline), the prescapular nodes (just in front of the shoulder joint), and the popliteal nodes (on the back of the hind leg, opposite the knee). Some vets also check the armpit area and the groin, though those nodes are harder to locate in a healthy dog.
Normal lymph nodes feel like small, smooth, movable lumps roughly the size of a bean in a medium-sized dog. They shouldn’t be tender. When they’re swollen, they can grow to several times their normal size, sometimes becoming visible without even touching the dog. The mandibular nodes under the jaw and the prescapular nodes near the shoulders tend to enlarge most noticeably in systemic illness.
Common Causes of Swollen Lymph Nodes
Lymph nodes swell because they’re doing their job: filtering out threats and producing immune cells. The underlying cause generally falls into one of three categories.
Infections
A bacterial skin infection, an abscessed tooth, or a wound on a paw can cause the nearest lymph node to enlarge as it fights off the invading bacteria. This type of swelling is usually localized to one area. Fungal infections like blastomycosis and histoplasmosis can also trigger lymph node enlargement, sometimes in deeper nodes inside the chest that only show up on X-rays. Tick-borne diseases are another important cause. Lyme disease, for example, can produce lymph node swelling alongside shifting leg lameness and fever, with symptoms typically appearing two to six months after an infected tick bite. Your vet may also test for related tick-borne infections like Ehrlichia and Anaplasma, which cause similar signs.
Cancer
This is the cause most owners fear, and it’s a legitimate concern. In one study of dogs with enlarged lymph nodes inside the chest, 79% had cancer. The most common type is multicentric lymphoma, a cancer of the lymphatic system itself. Other cancers, including mast cell tumors, hemangiosarcoma, and melanoma, can spread to lymph nodes from elsewhere in the body. Cancer-related swelling tends to affect multiple lymph node sites at once, and the nodes often feel firm and rubbery rather than painful.
Immune-Mediated Conditions
Less commonly, the immune system itself misfires and causes node enlargement. Conditions involving abnormal blood clotting or destruction of platelets have been associated with swollen lymph nodes, though these cases are relatively rare compared to infections and cancer. In young dogs, lymph nodes can also be slightly enlarged simply because their immune systems are still developing and responding to new environmental exposures.
What Lymphoma Looks Like in Dogs
Lymphoma deserves its own discussion because it’s the most common cancer linked to swollen lymph nodes, and its presentation can fool owners. Many dogs with early-stage lymphoma look and act completely healthy. The only sign is firm, painless swelling in multiple lymph node locations, something an owner might discover while petting their dog or giving a bath.
As the disease progresses, dogs may lose their appetite, lose weight, become lethargic, develop vomiting or diarrhea, or have difficulty breathing. The cancer is staged from I (one lymph node involved) through V (spread to the bone marrow or bloodstream). Dogs are also classified as substage “a” if they still feel well, or substage “b” if they’re showing systemic symptoms. That distinction matters because dogs who still feel good at diagnosis generally respond better to treatment.
Certain breeds carry higher risk. Rottweilers, Dobermans, Boxers, and Bernese Mountain Dogs show a significant predisposition to lymphoma, with odds ratios above three in multiple countries studied. Boxers tend to develop T-cell lymphomas, while Rottweilers more often get B-cell lymphomas, a distinction that affects treatment response and prognosis. Labradors aren’t predisposed overall but, when they do develop lymphoma, it tends to be an aggressive T-cell form.
How Vets Diagnose the Cause
The first diagnostic step is almost always a fine needle aspirate. Your vet inserts a thin needle into the swollen node, draws out a small sample of cells, and sends it to a lab for examination under a microscope. The procedure takes seconds, causes minimal discomfort, and rarely requires sedation. It’s enough to distinguish between infection, reactive swelling, and many cancers.
When the aspirate results are inconclusive, the next step is a tissue biopsy, which removes a larger piece of the node and preserves its internal architecture. This gives a more definitive diagnosis but carries slightly more risk of bleeding and usually requires sedation or anesthesia. Lab fees for lymph node cytology run around $80 to $90, with biopsy processing starting around $130, though the total cost of the visit will be higher once you factor in the exam, sedation, and any imaging.
If cancer is confirmed, your vet may recommend chest X-rays, abdominal ultrasound, and blood work to determine how far the disease has spread. This staging process guides treatment decisions and helps predict outcomes.
How to Check Your Dog’s Lymph Nodes at Home
Regular at-home checks take less than a minute and can catch problems early, especially if your dog belongs to a high-risk breed. Start under the jaw: slide your fingers along the underside of the lower jawbone, feeling for small oval lumps in the soft tissue. They’re more mobile than the salivary glands, which sit further back and feel more fixed in place.
Next, move to the prescapular nodes. With your dog standing, gently press into the area just in front of each shoulder joint, gradually increasing pressure. In a normal dog, these nodes may be subtle or barely detectable. Finally, check the popliteal nodes by feeling the back of each hind leg at the level of the knee, in the groove between the two large muscles. Compare both sides. A node that’s noticeably larger on one side, or nodes that are enlarged across multiple locations, are worth a vet visit.
You’re looking for anything that’s new, growing, asymmetric, or firm. Monthly checks give you a reliable baseline so you’ll notice changes quickly.
Signs That Need Prompt Attention
Swollen lymph nodes on their own are worth getting checked, but certain combinations of signs call for faster action. Rapid enlargement over days rather than weeks, swelling in multiple locations simultaneously, and lymph nodes that are hard and immovable all raise the likelihood of cancer. If swollen nodes near the throat are causing difficulty breathing or swallowing, that’s a true emergency.
Swelling paired with fever, lameness, loss of appetite, unexplained weight loss, or increased thirst and urination also warrants a prompt appointment. These systemic signs suggest the underlying cause, whether infection or cancer, is already affecting your dog’s overall health.