Lumps, Bumps, and Cysts on Dogs

Lumps, bumps, and cysts on dogs can be benign (noncancerous) or malignant (cancerous).

You can’t determine whether a growth is cancerous just by looking at it. A veterinarian may need to examine the lump and take a sample of cells to make a diagnosis and recommend treatment.

Here’s what pet parents should know about common lumps on dogs, including their appearance, diagnosis, and treatment.

What Are the Different Types of Lumps on Dogs?

There are several types of lumps on dogs, including benign (noncancerous) and malignant (cancerous) growths. These skin growths can vary in appearance, location, and severity.

Benign (Noncancerous) Lumps on Dogs

Tumors that are benign are not likely to spread to other areas on the body.

Histiocytoma

A histiocytoma is a benign skin growth that usually occurs in dogs less than 2 years of age. They are found on the front half of a dog’s body, usually as a lump on a dog’s head or a lump on a dog’s legs.

Rarely, they can be seen in older dogs or on other areas of the body.

Histiocytomas are pink and fleshy but may get bigger and seem more irritated before improving.

These tumors usually regress spontaneously over time without treatment and arise from the skin’s immune cells. They can be diagnosed through microscopic examination of a sample of cells from the growth.

Lipoma

A lipoma is a growth made of fat cells that can develop under a dog's skin or within muscle tissue. Lipomas may appear anywhere on a dog's body but are common on the trunk and legs.

They usually develop in older, overweight dogs. They may become quite large or appear in multiple locations.

A veterinarian can diagnose a lipoma by taking a small sample of cells from the growth to look for fat droplets.

No treatment is needed if they are not bothersome, but these should be monitored for rapid changes.

They will gradually enlarge with time and may bother your dog if they’re located in an area that interferes with motion. When lipomas start to bother your pet, you can consider surgical removal.

Lipomas should be carefully monitored over time as they can transform into cancerous growths called liposarcomas.

Papilloma

A papilloma is a contagious, wart-like growth that commonly develops in and around the mouth of young dogs. In older dogs, papillomas may appear around the eyes or on other areas of the body.

Papillomas are caused by a virus that can be spread through direct contact with an infected dog or contaminated items, such as toys or feeding bowls.

They appear small, fleshy, and round with a cauliflower-like texture to the surface.

Many will dry up and fall off within a few months as the dog’s immune system matures. Severe cases may make eating or swallowing difficult and require treatment by surgical removal.

Medications and other treatment methods are also available, including crushing of the warts to stimulate the immune system.

Skin Tag

A skin tag is an overgrowth of connective tissue that typically develops where a dog’s skin rubs together. Skin tags are usually the same color as the surrounding skin and extend from the surface on thin stalks.

Skin tags are common in older dogs and certain breeds. No treatment is needed, but these can be surgically removed if they are bothersome.

Sebaceous Gland Tumor

A sebaceous gland tumor is a skin growth commonly found in older dogs. These tumors are typically smaller than a pea and can develop anywhere on the body. Some will bleed or secrete a material that forms a crust.

Large breeds often form these on their head, specifically their eyelids, and they may be black in color. Treatment is not necessary, but surgical removal may be considered when the growth is bothersome.

Meibomian Gland Tumor

A meibomian gland tumor is a slow-growing benign lump that forms in the meibomian gland at the edge of the eyelid. This gland produces tear film, and a growth can develop when it becomes clogged.

They are often cystic and filled with fluid. The tumor can stick out or grow into the eyelid. They may become inflamed, irritated, painful, or ulcerated. They may also cause inflammation of the cornea and conjunctiva.

Large tumors may cause problems when your dog blinks, because they cause extra tearing and tear staining.

Meibomian gland tumors are diagnosed by their appearance and location. They can be surgically removed, or the tissue can be frozen for removal.

They rarely grow back after removal, but regrowth is possible.

Epulis

An epulis is a common benign growth found in the mouth of dogs. They may form when a tooth rubs against the gums, as with an underbite in brachycephalic (flat-faced) breeds.

These smooth, fleshy, pink bumps grow on the gum tissue near the outer surface of an incisor, canine, or premolar tooth.

They can appear to grow on a stalk of tissue, like a mushroom, or as an unmoving mass, and they may have a bony interior. Certain types can invade surrounding bony tissue.

An epulis may be identified by its appearance and confirmed with a biopsy. An X-ray of your dog’s head can show whether the growth has invaded surrounding tissues.

These growths should be removed surgically, along with the adjacent tooth and any bony tissue that may be affected.

They do not usually regrow if the entire tumor is removed. Radiation therapy may help cases where the growth is inoperable.

Follicular Cysts

Follicular cysts are benign skin bumps that develop from hair follicles in dogs. They may release a thick material that is white, yellow, or brown when you push on them. As they get bigger, they can become itchy or painful.

Follicular cysts are diagnosed through a physical examination and may be confirmed by examining a small sample of cells collected with a needle under a microscope.

Follicular cysts may become infected and require antibiotic treatment. If they are growing or become painful, they may be surgically removed and should not regrow.

Perianal Adenomas

Perianal adenomas are benign growths common in older, unneutered male dogs. They grow from oil glands near the anus but can also occur in similar glands along the abdomen, on the back, and near the tail.

Perianal adenomas commonly appear as multiple small lumps. Larger tumors may develop bleeding ulcerations and can compress the anal canal, making it difficult for your dog to poop.

Almost all male dogs are cured by neutering alone, but large or ulcerated tumors may also be surgically removed. Females improve with surgical removal, but the growths often recur.

Laser surgery or freezing the growth may be necessary to avoid fecal incontinence when surgery involves the anal sphincter.

Hemangiomas

Hemangiomas are benign tumors of blood vessels that occur in adult dogs. They commonly develop in areas with sparse hair, such as the legs, trunk, or underbelly.

They may be single growths or multiple, compressible, reddish-black circular lumps that can resemble a blood blister. Some may become large and even ulcerate. The recommended treatment is surgical removal.

Nevus

A nevus, commonly called a mole, is a benign skin growth that can appear as a dark, raised or flat lump. These are found on areas prone to trauma, such as the legs, head, and neck, usually in older dogs. Treatment is surgical removal.

Trichoepitheliomas

Trichoepitheliomas are small, benign lumps that develop from the hair follicles of adult dogs.

They are cyst-like and filled with condensed, yellow, cheesy, granular material. They can occur anywhere on the body, but especially on the face and trunk.

Treatment is surgical removal, but additional trichoepitheliomas may develop in other locations even after surgery.

Cornifying Epitheliomas

Cornifying epitheliomas are benign skin growths that protrude from the surface and resemble horns.

They arise from hair follicles and may form anywhere on a dog’s body, but they are more common on the back, tail, and legs of adult dogs.

No treatment is necessary unless there is evidence of self-trauma, ulceration, or secondary infection. In those cases, surgical removal is the ideal treatment.

Basal Cell Tumors

Basal cell tumors are benign growths that develop on the head, ears, neck, and forelimbs of older dogs. They are raised swellings that are typically firm, solitary, dome-shaped, and small.

Some may be hairless, ulcerated, and protrude from the skin on stalks. They are dark in color and may form cysts that break open and drain fluid or pus.

Treatment is surgical removal, especially when the dog is uncomfortable.

Malignant (Cancerous) Lumps on Dogs

Malignant lumps on dogs are cancerous growths that can invade surrounding tissue and spread to other organs.

Angiosarcomas

Angiosarcomas are highly malignant blood vessel tumors that can vary in appearance. They may appear as one or more red lumps in the skin or underlying soft tissue, or as a poorly defined bruise.

All types grow rapidly and destroy surrounding tissue.

They also spread to or originate in the spleen, lungs, and liver. Angiosarcomas may occur in response to sun exposure in dog breeds with short, white coats, but dogs with dark, thick coats can develop them as well.

They usually form on the underside of the trunk, hip, thigh, and lower legs. A biopsy is required for a diagnosis.

Freezing and laser surgery can help control smaller surface tumors. Surgical removal is needed for tumors below the skin’s surface.

Chemotherapy may also be recommended to treat any remaining tumor cells.

Basal Cell Carcinomas

Basal cell carcinomas are malignant skin growths that can appear as flattened or raised lumps anywhere on the body of an older dog.

They may spread to surrounding skin, forming new ulcerations, but they rarely spread to other organs. Surgical removal is recommended, including enough surrounding skin to help ensure that no tumor cells remain.

Liposarcomas

Liposarcomas are rare, malignant tumors of fatty tissue that may develop in older male dogs, particularly on the chest and legs.

They can be soft or firm lumps that are slow to spread to other locations. Treatment is surgical removal, but recurrence is common. If this happens, radiation treatment may also be required.

Lymphosarcoma

Lymphosarcoma is a malignant tumor that rarely develops directly on a dog's skin but may appear as a surface tumor or alongside internal tumors.

It can look like flaky skin, red patches, raised and ulcerated areas, or lumps deep within the skin.

There are two forms of skin lymphosarcoma that differ in their expected progression and response to treatment, so it's important to determine which type your dog has early on.

Treatments include surgical removal, chemotherapy, and radiation, done separately or combined.

These treatments may improve the signs of the disease but do not lengthen the dog’s life expectancy.

Mast Cell Tumors

Mast cell tumors are the most common malignant tumor seen in dogs.

They often affect older dogs but can occur in dogs of any age—even puppies.

They develop solitary growths anywhere on the body, especially the limbs, lower abdomen, and chest. Larger or rapidly growing tumors and those in certain locations are more likely to spread.

Their appearance can vary greatly, but most are red, raised, and either soft or firm to the touch. These tumors release chemicals, including histamine, which can cause them to repeatedly increase and decrease in size, similar to an allergic reaction.

Your veterinarian will need to examine a sample of cells from the growth under a microscope to confirm a diagnosis. There is variation on how aggressive these tumors are.

Surgical removal is necessary. If the tumor regrows or spreads, other treatments—including chemotherapy and radiation—may be used.

Malignant Melanomas

Malignant melanomas are cancerous tumors that can develop in older dogs, commonly on the lips, mouth, and nail beds of male dogs.

They appear as raised, ulcerated lumps and may be dark, light gray, or pink. If they appear in the nail bed, the toe is often swollen.

These tumors grow quickly and may spread quickly to other organs. Complete surgical removal is the preferred treatment, but it may be difficult and involves removal of adjacent tissue to prevent recurrence.

Chemotherapy and radiation are not effective treatment options. A vaccine is available that helps shrink the size of the tumor, which may prolong your dog’s life expectancy.

Fibrosarcomas

Fibrosarcomas are common, fast-growing malignant tumors in dogs. Most are on the trunk and legs and vary in appearance and size.

Fibrosarcomas beneath the skin's surface may appear lumpy, while those deeper under the skin may feel firm and fleshy.

They can invade underlying muscles, but most do not spread to other areas of the body. Treatment consists of surgical removal, though complete removal may not be possible, and regrowth is common.

Fibrosarcomas may also be treated with radiation and chemotherapy.

Squamous Cell Carcinomas

Squamous cell carcinomas are malignant tumors that can develop on the surface of a dog's skin or beneath a nail.

Most appear as firm, raised, irregular, and ulcerated areas.

Many are solitary, but areas of prolonged sun exposure may produce multiple tumors. These growths invade surrounding tissues. Some are slow to spread, while others grow more rapidly.

Treatment involves complete surgical removal of the tumor along with some normal tissue.

How Do Veterinarians Diagnose Lumps on Dogs?

Veterinarians diagnose lumps on dogs through a physical examination and, when needed, microscopic examination of cells or tissue samples. Common diagnostic methods include impression smears, fine needle aspiration (FNA), and biopsy.

Physical Examination and Monitoring

When you find a growth on your dog, have your veterinarian do a physical exam. If your dog is biting, scratching, or licking at a bump, consider putting a recovery cone or suit on them until you can get an appointment with your veterinarian.

It’s helpful to note the location of the lesion, how long it’s been there, any changes that have occurred since you first noticed it, and whether your dog seems bothered by the growth.

Taking a series of photographs can be helpful for your veterinarian to make a diagnosis.

Diagnostic Tests for Lumps on Dogs

A sample of cells may need to be taken and evaluated under a microscope for a diagnosis.

This can come from taking an impression of the surface of the growth, using a syringe and small needle to withdraw a small sample of cells in the exam room (FNA), or surgically removing a small tissue sample (biopsy) while your dog is under local or general anesthesia.

Most veterinarians evaluate impression smears or fine needle aspirates by staining the slide and examining it under a microscope in the veterinary office.

Trained veterinary pathologists are available to analyze these same samples or small tissue samples to determine a diagnosis. Then your veterinarian can determine the appropriate treatment recommendations and explain the expected outcome.

How Are Lumps on Dogs Treated?

Treatment for lumps on dogs may include monitoring for changes, freezing or laser treatments, surgical removal, chemotherapy, or radiation.

Treatment options include:

• Monitoring for changes
• Removal by freezing or laser treatments
• Surgical removal of the lump with or without also removing some normal tissue
• Chemotherapy
• Radiation

How To Monitor Lumps on Dogs

To monitor lumps on dogs, keep a log of their appearance, location, and any changes over time.

Keep a log where you write down:

• When you first noticed the lumps and/or bumps
• How many there are and where they are located
• The size, color, and texture
• Whether it’s moveable or seems to be fixed to underlying tissue
• Whether there is any discharge present

Take pictures and note any changes from day to day in any of these factors.

Make an appointment with your veterinarian as soon as possible and bring your log and photos along with any questions you may have.