A raised lump on a black dog's abdomen.

Skin Growth, Lump, Swelling or Mass in Dogs

Skin growths are lumps of tissue that are within the skin or can be felt under the skin. Dogs can develop small bumps (papules) or larger bumps (nodules) on their skin. These lumps and bumps are fairly common occurrences, especially in the older dog.

Below is an overview of skin tumors and lumps in dogs followed by in-depth information about figuring out about benign vs. malignant tumors as well as the diagnosis and treatment of treating skin tumors.

Very often the word “lump” brings the word “cancer” to mind. However, there are many other causes of lumps. A skin growth or mass may be a malignant or benign tumor, an abscess, a cyst, a hematoma (blood-filled mass) or a reaction by the skin to an allergen (hives). Lumps are often benign accumulations of fat called lipomas. However, all lumps should be evaluated for the possibility of malignancy.

When is a Lump Cause for Concern?

Any new lump or bump should be evaluated right away, especially a lump that is rapidly growing, is warm or painful, is ulcerated or bleeding, is irregular in shape or is well attached to the tissues under the skin. Any of the above signs should prompt you to seek veterinary attention.

Different Types of Skin Tumors and Lumps in Dogs

A skin mass or lump can be within the skin, in the tissues under the skin or attached to the skin and underlying tissues. Thus, any proliferation of cells, pocket of fluid or debris, or swelling of the dog’s tissues can cause a mass. The health impact depends on the severity of the cause of the growth and the success in treatment of the problem.

The most common causes of skin growth are tumors, malignant and benign, bruises, infections and other causes.

Malignant Dog Tumors

Malignant tumors are proliferations of abnormal cancerous cells that endanger the dog by either invading nearby tissues or spreading to other areas of the body (metastasis). There are too many types of skin tumors to list here, but some of the more common ones are:

Benign Dog Tumors

Benign tumors are proliferations of cells that do not invade other tissues or spread to other locations. They are only dangerous when growing in a confined space, like in the head where they may compress the brain. They may need removal if they inhibit any important function or if they become damaged and bleed or become a nuisance. Some common benign tumors are listed below.

Diagnosing Skin Lumps in Dogs

Diagnosis may include the following:

Treating Skin Lumps in Dogs

The treatment will depend on the final diagnosis.

Malignant tumors may be surgically removed, treated with chemotherapy, treated with radiation therapy or a combination may be used. Benign tumors often are not removed unless they become a nuisance. Abscesses are often lanced, cleaned and flushed. Once this is done, antibiotics are much more likely to be successful.

Hematomas are treated by identification and elimination of the underlying cause. Hematomas caused by trauma often heal without treatment. Cysts may be opened, drained and flushed, treated by removal of the entire cyst or left alone if they don’t bother the owner or the dog. Hives or other allergic reactions are treated with anti-inflammatory drugs, such as steroids and antihistamines.