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Hard Lump on Cat’s Lower Jaw: Causes & Care

Written by: Dr. Rachel Ellison DVM (Veterinarian)

Last Updated on April 12, 2024 by Catster Editorial Team

Cat with a bad jaw

Hard Lump on Cat’s Lower Jaw: Causes & Care


Dr. Rachel Ellison Photo


Dr. Rachel Ellison

DVM, Veterinarian

The information is current and up-to-date in accordance with the latest veterinarian research.

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If a cat pet parent were to find a lump on their cat’s lower jaw, they are likely to be very concerned. While there could be various causes or medical issues present, having the cat seen promptly allows for the extent of the issue to be determined and for an attempt at diagnosis and potential treatment to be made.

In this article, we’ll explore some of the potential causes of such a lump, and some recommended temporary care tips while awaiting having your cat seen by their doctor.

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A Word on the Lower Jaw

The jaw itself consists of upper and lower bones that form the framework of the mouth entrance, and which hold the teeth in place. In addition, the jaw bones, coupled with the surrounding temporomandibular joint, allow for movement to open and close the jaw as well as for the grabbing and handling of food. In mammals, the lower jawbone can also be referred to as the mandible.

To a pet parent, “a lump on the jaw” may mean one thing, but to the veterinarian, it will prompt more investigation to determine exactly where it is and how far it may extend. Is it cutaneous (on the skin) nearby or directly over the area of the jaw? Is it bony (literally on the bone of the jaw)? Is it within or in between the jaw bones? Close to, but not exactly on the jawbone? Is it facing the inside of the mouth or on the exterior surface of the face? Is it towards the front tip of the jaw or the back?

As you can see, the lower jawbone can actually encompass many areas, and vets need to define it as accurately as possible to help in the next steps.

cat with open mouth and teeth
Image Credit: birgl, Pixabay

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Causes of a Hard Lump on the Jaw

Let’s get into what some different causes of a lump on the lower jaw could be. While not an exhaustive list, these are some important and potential categories.

 1. Infection

tired or sick cat
Image Credit: Kginger, Shutterstock

An infection could be on or in an area of the jawbone itself. It could be a bone infection from bacteria or fungi and is termed osteomyelitis. An abscess, which is an area of walled-off infection that typically contains pus can also be responsible. It is not uncommon to see a tooth root abscess or a rotten tooth in this area. In addition, an abscess could also be from a bite or scratch in an altercation with another animal.

Care tips:
If your cat is afflicted with an area of infection, it will likely be swollen and painful. It is important to NOT give any medication to a cat without the direction of a veterinarian. Human medicine that helps decrease pain and inflammation (such as acetaminophen, ibuprofen, aspirin, etc.) can make a cat more ill and may even be fatal.

If a cat is in pain, allowing them a low-stress, comfortable, and quiet place to be until they can be seen is best.

Switching food quickly can cause an upset gastrointestinal (GI) tract so if they already eat canned food, you should continue to offer this. If they normally eat dry food, pre-moistening it in warm water or some low-sodium chicken broth may help soften it and make it less painful to eat than hard food.

2. Enlarged Lymph Nodes

Submandibular (under the mandible) lymph nodes are present in an area just underneath the jawbone of a cat. There is one on the left side and one on the right. If one (or both) are enlarged, this could be due to various reasons such as inflammation, infection, or tumor cells.

Care tips:
While waiting for your cat’s appointment, pay attention to any noted health changes so this can be relayed to the veterinarian. Signs such as when the lump was first noticed, if any weight loss or loss of appetite are present, as well as weakness or pain can all be helpful. Allow your pet to do as much as they are comfortable with if they are not feeling well.

3. Cyst

cat lying on blanket looking sad or sick
Image Credit: Julia Cherk, Shutterstock

A cyst is a non-cancerous sac or lump that contains liquid and/or solid materials. This may be from body secretions (such as sebum, a substance made from oily wax) or the breakdown of cells. They are often small and round in size, and there are various types including true cysts, sebaceous cysts, follicular cysts, etc. While they are most often harmless, in some circumstances, they may need to be surgically removed.

Care tips:
Try to keep your cat from bothering or scratching at this area as much as possible so it is less likely to bleed or get infected. If they are bothered by it, a proper fitting cone of shame (Elizabethan collar) may temporarily come in handy.

4. Granuloma

This is a firm mass of immune system cells that accrue over time due to inflammation. The grouping of immune cells functions to wall off something that the body views as harmful which could include a foreign object, bacteria, etc.

In cats, there is a condition called the feline eosinophilic granuloma complex (EGC) that can consist of three different reaction patterns that are most often thought to be associated with allergic hypersensitivity. Only one of the three patterns, called an eosinophilic granuloma, is an actual granuloma. It can be found across the body, but one common area is inside the mouth.

Care tips:
Even if the cat is in pain, please do not give medication to them without consulting a veterinarian. As discussed, if feeding dry food, one can mix warm water with kibble to decrease potential pain from eating hard food. The source of the granuloma will need to be found before treatment can be tailored to the cause.

5. Tumor

Hand petting old sick brown striped sad senior cat
Image Credit: catinrocket, Shutterstock

Some kinds of cancer can be more commonly seen within or around the jawbone. In fact, for cats, the oral cavity is the fourth most common area where cancer is seen.  Depending on the type, some tumors may primarily affect or secondarily invade bone.

Some tumor types in this area could include:
  • Squamous cell carcinoma: This is the most common and consists of more than 75% of all oral tumors. It forms on the tissues around the teeth or underneath the tongue.
  • Fibrosarcoma: These are the 2nd most common oral tumor in cats.
  • Oral melanoma: This is an aggressive cancer that occurs in the mouth, is invasive to bone, and can metastasize quickly.
  • Osteosarcoma: This type of cancer is of the bone and while not very commonly seen in the bones of the jaw/mouth, is still possible.
  • Lymphoma (LSA): While there are various forms possible, peripheral nodal LSA is one type that takes place in a lymph node, chain of nodes, or lymph nodes throughout the body.
Care tips:
Without sampling and looking at the cells under the microscope, there is no way to know for sure if the lump is cancerous, and if so, the type of tumor. If it is a tumor, the smaller it is, the easier it will be for removal or therapy and overall treatment. Once oral cancer reaches a certain point, removal may no longer be an option, and remaining care may focus on attempting to delay tumor growth and/or hospice care.

Therefore, regularly inspecting for physical changes in your cat, including in their mouth if they will let you safely, may allow for the process of earlier diagnosis and treatment.

Common Signs

Some common signs of a lump on (or around the jaw) that may be seen include oral pain, becoming “head shy” which is not wanting to be touched on the head, very bad breath, drooling, loss of teeth, facial swelling, decreased appetite or difficulty eating, and lymph node enlargement.

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Diagnosis and Treatment

A thorough oral exam and full physical exam of your cat will help the veterinarian formulate a list of potential diagnoses. To start the process of confirming a diagnosis, this may begin with a fine needle aspiration (FNA), which uses a small needle to take a sampling of the cells to be observed under the microscope. Further testing may be indicated such as with radiographs (X-rays) or a biopsy (larger sample of tissue to be examined under the microscope). In some instances, further care from specialists, such as a veterinary surgeon or oncologist, may be utilized. 

Treatment of the lump will depend on the exact cause. If a tooth is infected, it will need to be removed. An abscess is often cleaned out very well before medications are started. If there is an infection, bacteria will be treated with antibiotics and a fungal infection with antifungals. In most instances, medication for pain and inflammation will be needed. Other types of diagnoses may need surgery with or without chemotherapy and/or radiation.

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As we have learned, a lump on your cat’s jaw could have a variety of medical implications which range from minor to very serious. If a lump on the jaw is observed, receiving veterinary medical attention quickly can help your cat not only relieve their pain and discomfort but in some cases, also have a higher chance of resolving the medical issue.

Thus, it is vital to contact your veterinarian promptly if you ever encounter a lump of this kind on your cat.

Featured Image Credit: zeelbervarg, Shutterstock

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