However, not every enlarged lymph node is inflamed, and not every change is tender. The general term for enlargement is lymphadenopathy. Lymphadenitis specifically means inflammation of a lymph node. Tests distinguish reactive enlargement, inflammation of the node and accumulation of tumour cells.
When to see a vet urgently
Seek emergency care if swelling or other signs of illness are accompanied by any of these signs:
- difficulty breathing or open-mouth breathing;
- inability to swallow or eat normally;
- severe weakness, collapse or rapidly worsening general health;
- very painful, rapidly increasing swelling together with lethargy suggesting fever.
Do not squeeze or puncture a lump. You can find a vet near you. A new or growing lump needs examination even if your cat otherwise seems well and has no emergency symptoms.
Overview
Lymphadenitis is not a disease in its own right but a sign of many different illnesses. It is most often associated with bacterial, viral, parasitic or fungal infections, as well as autoimmune disease and tumours. Inflammation may be acute or chronic and affect one or more lymph nodes. Depending on the location, it may involve nodes under the jaw, in the neck, in the groin or behind the knee, for example.
A lymph node receives tissue fluid from lymphatic vessels and helps identify substances foreign to the body. A local node may react to inflammation in the area from which its lymph drains. Assessing the nodes under the jaw therefore also includes examination of the mouth and nose. An enlarged node does not necessarily mean that a pathogen is multiplying inside it.
Not all lymph nodes can be felt through the skin. Changes in nodes within the chest or abdomen may only be found through imaging. Changes in one area and in several areas guide investigations differently, but do not yet identify the cause. The size and structure of nodes are compared with other findings.
Causes
The most common causes of lymphadenitis in cats include:
- Bacterial infections, such as abscesses, infected wounds and pyoderma.
- Viral diseases, including feline leukaemia virus (FeLV), feline immunodeficiency virus (FIV) and calicivirus.
- Parasitic and fungal diseases, such as toxoplasmosis and cryptococcosis.
- Immune system disorders, including autoimmune diseases.
- Tumours, such as lymphoma and metastases.
A tumour can enlarge a lymph node without true lymphadenitis, but inflammation and a tumour can also occur in the same sample. Finding inflammatory cells therefore does not rule out another disease in every situation. Nor does the possibility of viral infection mean that every enlarged node is caused by FeLV or FIV.
Toxoplasma infection is often acquired from prey or raw meat, but most infected cats do not develop clinical toxoplasmosis. Symptoms, travel and other exposure details are considered when investigating a possible fungal disease or another less common infection. Not every cat is tested for all the listed causes with the same test panel.
Risk factors
- Cats that roam freely outdoors, with more opportunities for exposure to infections.
- Cats with reduced immunity.
- FeLV- or FIV-positive cats.
- Young, active cats that play vigorously and have a high risk of injury.
- Cats from shelters and breeding establishments where infections are more common.
Information on the precise effect of these factors on feline lymphadenitis risk is limited. In particular, vigorous play in a young cat or a previous shelter or breeding background does not alone establish the cause of enlargement. FeLV or FIV infection may alter the investigation and treatment plan, but a positive result does not replace assessment of the lymph node itself.
Typical symptoms
- Enlarged lymph nodes that can be felt with the fingers.
- Tenderness when touched.
- Fever.
- Tiredness and reduced appetite.
- Swelling and inflammation in the affected area with local infections.
- Enlargement of several lymph nodes and declining general health with systemic illness.
Feeling a node cannot reliably distinguish inflammation, a reactive change and lymphoma. A salivary gland or another structure in the neck can also feel like a lymph node. Repeated forceful squeezing can make the area sore, so your role is to notice the change rather than test what it contains.
When a local bacterial infection is suspected, the vet looks for a bite wound, an abscess or another source of infection, for example. The opening in the skin may be small and hidden under the fur. Fever, loss of appetite and pain may relate to this primary problem. Disease in a deeply located lymph node, on the other hand, may cause only general symptoms.
Complications and consequences
Untreated lymphadenitis can lead to:
- pockets of pus and abscesses;
- infection spreading throughout the body, or sepsis;
- chronic inflammation;
- complications of the underlying disease, such as a viral infection or tumour.
Complications depend on the cause. Bacterial inflammation involving pus can form an abscess, but a reactive node or tumour does not automatically develop into an abscess or sepsis. Enlargement of several nodes does not alone prove that infection has spread into the blood either. Rapid deterioration always needs separate assessment.
Diagnosis at the vet
Diagnosis involves:
- a clinical examination and feeling the lymph nodes;
- a complete blood count and blood biochemistry;
- a cell or tissue sample from the lymph node to assess inflammatory cells and tumour changes;
- PCR and antibody tests to investigate viral and parasitic infections;
- ultrasound and X-rays if systemic disease is suspected.
The history includes when the lump was noticed, changes in size, pain, other symptoms, contact with animals and medicines used. The vet examines other lymph node areas and any possible local source of inflammation. Blood tests assess general health and organ function, but a normal blood count alone does not determine the nature of a lump.
A fine-needle sample is examined to identify the cells in the node and look for pathogens. It may show inflammation with pus, a reactive cell population or suspected cancer. Interpretation requires enough material taken from the right place. If the sample is sparse or the result does not explain the finding, a repeat sample or tissue biopsy may be needed.
Why might a tissue sample be needed?
A cell sample does not show the full architecture of a lymph node. A reactive change in a cat's node under the jaw in particular can look abnormal, and some lymphomas resemble normal or inflamed tissue. A pathologist's assessment and, where needed, histological examination help avoid an overly certain conclusion from one sample. Additional methods may be used if the distinction between inflammation and cancer remains unclear.
Infection tests are selected according to sample findings and exposure. A FeLV or FIV test result may need confirmation, and Toxoplasma antibodies can indicate past exposure. They do not alone prove that Toxoplasma is causing the current lymph node change. Bacterial or fungal culture may require a separate sample taken before treatment.
Treatment and prognosis
Treatment aims to control the underlying cause, rather than simply shrink the node. Bacterial inflammation may require antimicrobial medication and drainage of an abscess or treatment of another source of infection. The vet selects medicines and any procedures according to the findings. Swelling size alone is not a reason for antibiotics.
A parasitic or fungal disease needs treatment suited to that organism. For lymphoma, the plan may include chemotherapy or other cancer treatment, so it is not managed as an ordinary bacterial infection. An untreated local wound and a diagnosed cancer may look like similar lumps to an owner, even though their treatment and prognosis differ greatly.
Can the inflammation be immune-mediated?
Steroid-responsive lymphadenitis has been described in some cats after investigation for an identifiable infection, another source of inflammation and a tumour. The evidence comes from a small patient group, and symptoms returned in some cats. Do not try corticosteroids at home to establish a diagnosis. Treatment decisions are based on the overall investigation, rather than swelling alone.
Monitoring at home
Monitor appetite, activity, weight changes and changes in the lump as agreed. If the area is discharging, follow wound care instructions and prevent licking with a protective collar if necessary. Do not apply cleaning products or ointments to a deep wound without instructions. Agree medication changes with the treating vet.
At check-ups, both the lymph node and the underlying disease's response to treatment are assessed. A shrinking lump is a useful observation, but returning symptoms or enlargement of other nodes may require further samples. Prognosis depends on the cause, any spread and response to treatment. There is no single recovery time for every patient with lymphadenitis.
Prevention
- Treat your cat's infections promptly.
- Keep vaccinations against viral diseases up to date.
- Maintain regular parasite control.
- Keep your cat's environment clean and reduce stress.
- Arrange regular health checks, particularly if your cat is at risk.
Vaccines or parasite medicines cannot prevent every lymph node change. Reducing fights associated with free roaming lowers the chance of bite wounds and FIV infection. Toxoplasma exposure can be reduced by avoiding raw meat and hunting. FeLV protection and testing needs are planned according to your cat's contacts; vaccination does not provide complete protection in every exposure situation.
Important for cat owners
Lymphadenitis is a sign that inflammation or another disease process is occurring in your cat's body. Enlarged lymph nodes always need careful investigation because the cause may be a mild local infection or a serious systemic illness such as FeLV infection or lymphoma. Taking your cat to the vet promptly allows the cause to be identified and treatment started early.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Is an enlarged lymph node always lymphoma?
No. It may be reacting to local inflammation or be inflamed itself. A tumour is one possibility, distinguished from other causes by cell sampling, histological examination and other appropriate tests.
Can I puncture an inflamed lymph node myself?
No. The lump may be a structure or change other than an abscess, and handling it can cause pain and damage. A vet examines it and assesses whether a sample, medication or a procedure is needed.
Why does the first sample not always give a definite answer?
A cell sample may contain too little material, or inflammation and a tumour may resemble each other. A tissue biopsy also shows the node's architecture. A new sample may therefore be needed if the finding and result do not match.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
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- Colour Atlas of Canine Lymph Node Cytology, MSPCA-Angell, accessed 2026-11-03.
- Diagnosis of pyogranulomatous and neutrophilic lymphadenitis in 72 cats presenting to a referral hospital: with a focus on nine cats with steroid-responsive lymphadenitis, Journal of Feline Medicine and Surgery / PubMed, accessed 2026-11-03.
- Feline Immunodeficiency Virus (FIV), Cornell University College of Veterinary Medicine, accessed 2026-11-03.
- Guideline for Feline Leukaemia Virus Infection, ABCD, accessed 2026-11-03.
- Abscesses in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Guideline for Toxoplasma gondii Infection, ABCD, accessed 2026-11-03.
- Lymphoma, Cornell University College of Veterinary Medicine, accessed 2026-11-03.