The production of too many immune cells at once is what causes the lymphadenopathy. Either a solitary nodule can be effected, or a group of nodules. When this occurs in younger cats, it is generally due to an infectious disease. Swollen lymph nodes are a common finding in many sick cats. Infections and other complications signalled by inflamed lymph nodes need to be treated by a veterinarian as soon as possible for the best results.

Lymph nodes are ducts within the body that are used to collect fluid and return it to the bloodstream. Inside the lymph nodes, lymphocytes (white blood cells) destroy bacteria, fungi, viruses, and cancer cells. When the body faces infection, the lymph nodes located closest to the infection will swell or enlarge. This is referred to as lymphadenopathy.

As lymph nodes swell from many different types of infections all over the body, various symptoms can occur. Below are the most common symptoms associated with lymphadenopathy.

Generally, the cause of swollen lymph nodes has to do with a nearby issue in the body. These issues can range from minor to life-threatening and should be evaluated by a veterinarian. Causes are as follows:

The first thing that a veterinarian will need from you is your cat's extensive medical history. This can give clues to underlying problems that may have developed to cause the swelling. A physical examination of the cat will be completed to try and locate the affected lymph nodes by feeling key areas of the body. Often this will include the submandibular (where the jaw meets the neck), the axillary (armpit of the front legs), the prescapular (where the front leg joins the shoulder) and the popliteal (on the rear legs opposite of the knee) areas. If there is any pain in these locations, that is an indication of swollen lymph nodes. 

The vet will rule out all possible harmless syndromes by assessing all symptoms. Blood work will be done to get an overall picture on the cat's health. A complete blood count will show how many blood cells are present and indicate if cancer is the cause. A biochemical profile will show other substances in the blood. Urinalysis can help detect bacteria that may be causing infection. A lymph node biopsy to collect samples for microscopic examination may be needed if cancer is suspected. 

X-rays and ultrasounds can be used to detect tumors or other abnormalities on the lymph nodes. When any lymphadenopathy is present, Feline Leukemia Virus and Feline Immunodeficiency Virus should be tested for. A fecal parasitological exam may be needed if parasites are suspected. The vet may recommend more extensive testing until a cause has been identified.

To restore lymph nodes to their normal size, the underlying condition that is causing the inflammation needs to be treated. There are a number of different treatments depending on which ailment the cat is suffering from.

The corresponding antibiotic will be prescribed to eliminate a bacterial infection. Antibiotics are often prescribed for 2-4 weeks.

Antifungal medication, shampoo, or cream will be prescribed to eradicate a fungal infection affecting the cat. 

In the case of allergies, tests or the process of elimination will be used to identify the allergen. Once identified, the allergen will be removed from the cat’s environment or diet.

Most viral infections can only be treated symptomatically. The cat may need to be hospitalized for supportive care while fighting a viral infection. Intravenous fluids may be administered to keep the cat hydrated. Other care may be administered to keep the cat as comfortable as possible.

Cancer of the lymph nodes is very serious and needs to be treated aggressively. There are three main ways to treat cancer of the lymph nodes.

Once your cat is home, take care to administer all prescriptions exactly as requested. This can help ensure all infections are properly treated. If symptoms are not going away, further treatment and tests may be necessary to find the root of the issue. A check-up appointment will be needed to gauge if lymph node swelling has gone down. 

Once an infection has cleared out of the cat’s system, the lymph nodes should return to their normal size. If the cat has undergone surgery, extra care should be given to keep the incision clean and decrease all stress inducers during the healing process. It should be noted that in cases of lymph node cancer, prognosis is not great, with the maximum survival being about two years.