What Should You Do If Your Dog or Cat Has Swollen Lymph Nodes?

Finding a swollen lymph node on your pet is scary, and the right response is action rather than observation. An enlarged node means the immune system has identified something to address, and the range of possible somethings is broad: a tooth that has gone bad, an allergy that has progressed to a skin infection, a tick-borne illness picked up months ago, an autoimmune flare, or, in a smaller share of cases, cancer. There is no reliable way to determine which from the outside, and the response that protects your pet is the same regardless of the underlying cause. Get the node evaluated while the trigger is still easy to identify. Most swollen nodes lead back to a treatable explanation, and when they do not, moving early is what preserves the most treatment options.

At Tidmore Veterinary Hospital in Northport, we run a full range of AAHA-accredited diagnostic and treatment services so you get answers quickly. If your dog or cat has a swollen node or a new lump that was not there before, call us and we will take a look together.

Your Step-by-Step Action Plan

• Skip the wait-and-see: an exam is the move, since a lymph node will not reveal its cause on its own.
• Compare the matching side: check the same anatomical spot on the opposite side and the other node locations.
• Document what you find: size, firmness, tenderness, mobility, and timing of when it first appeared.
• Calibrate the urgency: a pet feeling unwell with multiple swollen nodes calls for same-day attention.

What’s the First Step When You Find a Swollen Node?

Begin by collecting information. With your pet calm, gently feel the corresponding node on the opposite side of the body and the other accessible node locations, using this guide to lymph node locations, so you can determine whether you are dealing with a single enlarged node or several at once. Note the dimensions roughly (think pea, marble, golf ball), whether the node feels soft like a grape or firm like a marble, whether your pet flinches when you touch it, and when you first felt it.

What to avoid matters equally. Resist the urge to squeeze, prod, or massage the node repeatedly. Skip any leftover medication from a previous problem, since lymph node enlargement has too many possible causes for guesswork to help. And do not let weeks pass to see whether the swelling resolves on its own, because the wait-and-see approach can cost critical time when the cause turns out to need prompt attention.

What Should You Do Based on What You Found?

The appropriate next step depends on the combination of what you felt and how your pet is behaving overall.

When you cannot clearly place your situation in a row, default to treating the more urgent option as your guide and call to describe what you are seeing.

How Do You Check the Rest of Your Pet’s Nodes?

A two-minute home check answers the most important diagnostic question: is the swelling localized to one spot or affecting multiple areas? With your pet relaxed and ideally in a familiar position like lying on their side or standing for petting, feel gently in each location:

• Under the jaw: run your fingertips along either side of the throat, just below the jawline, where the submandibular nodes sit.
• Front of the shoulders: at the junction where the neck meets the chest, the prescapular nodes are accessible.
• Inside the armpits: reach up and toward the body wall on each side to feel the axillary nodes.
• Along the groin: trace the inner thigh where the leg meets the body to find the inguinal nodes.
• Behind each knee: in the soft tissue behind the stifle joint, the popliteal nodes are usually the easiest to feel.

You are not making a diagnosis from this exam; you are establishing a baseline of what is normal so that change becomes obvious. Lymph node palpation is also a standard part of every preventive visit, one of the routine components of AAHA-accredited care that catches changes you might miss at home. Ask our team during your next wellness visit to show you the locations; if you can’t find their lymph nodes, consider that a good thing.

When Should You Call, and How Soon?

Match your timing to the clinical signs. Call for same-day care if multiple nodes have enlarged suddenly, if your pet seems lethargic or feverish, if their gums look pale, or if there is any difficulty breathing, swallowing, or eating. Schedule a visit within 48 hours for a single firm, painless lump in a node location, or for any node that was small at a recent visit and has grown noticeably. A stable, mildly enlarged node found on a home check, with your pet otherwise behaving normally, can usually wait for the week. When the urgency is genuinely unclear, call us and describe what you are feeling, and we will help you decide.

What Happens at the Appointment?

The visit proceeds in a logical sequence designed to deliver answers without unnecessary testing. The first step is a thorough hands-on examination, where we evaluate each accessible node for size, texture, mobility, and pain response, since a soft, painful, mobile node behaves clinically very differently from a firm, fixed, painless one. The next step in most cases is a fine needle aspiration, a quick, minimally invasive sample of cells from the node that rarely requires sedation and often answers the diagnostic question the same visit: reactive change, infection, or cancer. When cytology results are inconclusive or when confirming a cancer subtype matters for treatment planning, a biopsy provides a larger tissue sample for more definitive evaluation. Bloodwork, a tick-borne disease panel, and imaging fill in the broader picture, and our in-house laboratory means most results come back quickly.

What Might Be Causing the Swelling?

Understanding the range of possible causes makes the urgency conversation make sense, because the same lymph node finding can represent quite different underlying processes. Infections lead the list, and several are particularly relevant in the Southeast.

• Local infections: Dental disease, a tooth root abscess, a skin infection, ear infection or other superficial issue will all enlarge the nearest lymph node.
• Tick-borne disease: Lyme disease and ehrlichia and anaplasma are particularly common given Alabama’s long warm season and substantial tick populations.
• Bacterial disease: leptospirosis spreads through standing water and wildlife urine in this region, and feline mycobacteriosis sometimes appears as enlarged regional nodes.
• Fungal disease: the broader fungal disease category includes blastomycosis and histoplasmosis, both seen with some regularity in our region, along with aspergillosis anywhere and Valley Fever after travel to the desert Southwest.
• Feline viruses: the feline leukemia virus and feline immunodeficiency virus both affect the lymphatic system and warrant screening when feline nodes stay enlarged.
• Parasites: toxoplasmosis, intestinal parasites, giardia, and substantial external parasite burdens can all activate lymph nodes.

What If It’s Lymphoma?

Cancer is the cause families worry about most, and lymphoma deserves a fuller explanation than a passing mention. It is the most common cancer associated with enlarged lymph nodes in dogs, and knowing what it looks like, how it gets diagnosed, and what treatment can offer makes the conversation around a swollen node less frightening.

Canine lymphoma is a cancer of lymphocytes, the immune cells that populate lymph nodes. When those cells become cancerous, they multiply within the nodes and accumulate to produce the characteristic enlargement. The disease affects approximately 1 in 15 dogs and 1 in 8 Golden Retrievers across their lifetimes, making it one of the most common cancers in companion dogs.

The Lymphoma Presentation

Several features tend to distinguish lymphoma from infection-driven node enlargement:

• Painlessness. Lymphoma nodes are firm and rubbery without producing tenderness, while infection-related nodes are typically painful when touched.
• Symmetry. Multiple nodes on both sides of the body enlarge simultaneously, producing matching swellings under both jaws or behind both knees.
• A normal-acting pet. The most counterintuitive feature, and the one that delays many diagnoses, is that early lymphoma often appears in a dog who acts entirely normal. Eating, drinking, playing, and energy remain unchanged even as nodes grow visibly larger.
• Steady progression. Nodes that continue to enlarge over a week or two without an obvious cause warrant evaluation rather than additional observation.

Breeds and Risk Factors

Lymphoma can affect any dog, but certain breeds carry meaningfully higher rates. Golden Retrievers top the list, followed by Boxers, Bullmastiffs, Bernese Mountain Dogs, Rottweilers, Scottish Terriers, and Saint Bernards. Middle-aged and older dogs are at higher risk than younger ones, though lymphoma can occur at any age. For at-risk breeds, proactive cancer screening for earlier lymphoma detection using blood-based tests is increasingly part of senior wellness care, and it can identify the disease months before nodes become visibly enlarged.

Subtypes Drive Treatment

Lymphoma is not a single disease but a category of related cancers, and the subtype affects everything about treatment and outlook. The most common form in dogs is multicentric lymphoma, which involves peripheral lymph nodes and accounts for most cases families encounter. Less common forms include alimentary lymphoma (gastrointestinal), mediastinal lymphoma (chest), and cutaneous lymphoma (skin). Each anatomical type is further classified by the cell type involved (B-cell or T-cell) and grade (high or low), with B-cell lymphomas generally responding better to chemotherapy than T-cell forms, and high-grade tumors progressing faster but often responding more dramatically to treatment.

This is why lymphoma diagnosis and subtype matters so much for treatment planning. A fine-needle aspirate can usually confirm lymphoma, but flow cytometry or immunohistochemistry is required to determine the specific subtype, which guides treatment selection and the conversations we have about realistic expectations.

What Treatment Looks Like

Treatment options range from observation with palliative pain management to multi-agent chemotherapy protocols. Chemotherapy in dogs differs substantially from human chemotherapy in important ways: doses are calculated to maintain quality of life rather than push for maximum cell kill, side effects tend to be mild, and most dogs continue eating, playing, and acting like themselves throughout treatment. The realistic goal is remission and extended quality time rather than cure. With standard multi-agent protocols, the majority of dogs with multicentric B-cell lymphoma reach remission, with median survival times often exceeding a year. Some live considerably longer.

Other Cancers That Affect Nodes

Lymphoma is not the only cancer that enlarges lymph nodes. Various solid tumors, including mast cell tumors, melanoma, and several carcinomas, can spread from a primary site to nearby lymph nodes. A firm, fixed lymph node near a known skin mass or known tumor should be evaluated promptly, since detecting spread early shapes treatment planning significantly.

Feline Lymphoma

Feline lymphoma follows different patterns. In cats, the disease most commonly affects the gastrointestinal tract rather than the peripheral lymph nodes, and the presentation, treatment approach, and prognosis differ from canine lymphoma in important ways. Cats with peripheral lymph node enlargement still warrant evaluation, but the differential diagnosis includes a wider range of possibilities, including the feline viruses mentioned above.

What About Non-Cancer Causes?

A smaller group of conditions falls into neither the infection nor cancer categories:

• Immune-mediated hemolytic anemia: the immune system attacks the body’s own red blood cells, sometimes with reactive lymph node enlargement alongside.
• Chronic allergies with secondary skin infection: the draining nodes enlarge in response to the ongoing inflammation in the skin.
• Brief vaccination reactions: the node closest to the injection site may enlarge for a few days as a normal immune response and then resolve.

What Happens After the Diagnosis?

Once the cause is identified, treatment is tailored to it: antibiotics for bacterial and tick-borne infection, antifungals (typically for months) for fungal disease, immunosuppression for immune-mediated conditions, and chemotherapy for lymphoma, where remission rather than cure is the realistic goal. A local cause like a bad tooth is addressed at the source, and the affected node settles as the underlying issue resolves.

How Can You Reduce the Odds?

Not every cause of lymph node enlargement can be prevented, but the more common ones often can. A handful of habits cut the frequent causes out of the picture:

• Year-round flea, tick, and parasite prevention addresses the tick-borne and parasitic causes that are common here in Alabama.
• Current, lifestyle-appropriate vaccinations, including leptospirosis for pets in this region, lower viral and bacterial risk.
• Consistent dental care removes a steady source of jaw-node activation, since chronic periodontal disease keeps those nodes inflamed indefinitely.
• Routine wellness exams, with a complete node check at every visit, are the most reliable way to catch a change while it is still small and easy to investigate.

Frequently Asked Questions About Swollen Lymph Nodes

My Dog Has a Lump Under His Jaw. What Should I Do?

Schedule an exam rather than guess. A lump in that location could be an enlarged submandibular lymph node, a salivary gland issue, a fatty lipoma, an abscess, or several other possibilities. A fingertip examination plus, usually, a fine-needle aspirate sorts them out quickly. Acting on the finding early is always the safer call than waiting to see whether it shrinks.

Is It Urgent, or Can It Wait a Day or Two?

It depends on the broader picture. A single small node in a pet who feels fine can usually wait a day or two for a scheduled visit. Several swollen nodes, or any node combined with lethargy, fever, or trouble breathing, calls for same-day attention. When you are uncertain, a brief phone call settles the question.

What Should I Avoid Doing at Home?

A few things. Avoid squeezing or repeatedly handling the node, do not apply heat or home remedies, and do not start old medications. None of those interventions help, and some delay the right answer. Your role at home is to note what you find and book the exam.

What Information Helps Most When I Call?

Several specifics speed things along: when you first noticed the swelling, whether a single node or several are involved, whether the node feels soft or firm and painful or not, and any other changes you have noticed in appetite, energy, or activity level. If you can capture a quick phone photo, that helps too. The clearer your description, the faster we can gauge how soon your pet needs to be seen.

From Finding the Lump to Getting an Answer

The hardest part of finding an enlarged node is the gap between discovering it and knowing what it means. The way to close that gap is action: check the other nodes, document what you find, and book the exam. Most swollen nodes turn out to be reactive and resolve as the cause is treated, and even the harder diagnoses come with more treatment options when you move early.

If you have found something on your pet, request an appointment and our doctors will work through it with you.