The Definitive Guide to Dog Lumps and Bumps

Finding a lump on your dog can be alarming. Many pet owners immediately fear the worst when they feel a bump under their dog’s skin. Lumps can appear suddenly, feel unfamiliar, and raise concerns about serious conditions like cancer. The good news is that many lumps in dogs are harmless, especially as dogs age. However, some lumps can be serious and require prompt veterinary care. Understanding the different types of lumps, knowing when to worry, and learning what steps to take can help you protect your dog’s health and give you peace of mind. Understanding pet lumps is essential for recognizing and monitoring any changes, which is key to ensuring your dog's well being.

This dog lumps and bumps guide is designed to help pet owners better understand common growths in dogs, recognize changes early, and differentiate between benign and potentially serious conditions. Monitoring for changes and seeking timely veterinary evaluation is crucial, as early detection can significantly improve outcomes in cases where treatment is needed.

This guide will walk you through the most common types of lumps in dogs, including fatty tumors, cysts, mast cell tumors, and warts. We’ll also cover when to worry, how veterinarians diagnose these growths, and what supportive care options may help maintain your dog’s overall health. Regular checks are important for your pet’s health, helping with prevention and early detection, and seeking timely veterinary care can make a significant difference in early detection and treatment.

Types of Lumps in Dogs (Benign lumps vs Malignant lumps)

Dogs can develop many different kinds of lumps and bumps throughout their lives. Some are benign lumps, which are non cancerous and often harmless, while others may be malignant lumps, which can be more serious and require prompt veterinary attention. Lumps can appear under the dog's skin, on the dog's skin, or be attached to deeper tissues of a dog’s skin.

When evaluating a lump, veterinarians consider several important characteristics that help guide diagnosis. Size is often the first feature noted, as larger masses may raise more concern, although even small lumps can be significant depending on their type. Shape is another key factor; well defined, round lumps are often associated with benign growths, while irregular or poorly defined masses can sometimes indicate a more invasive process.

Texture also provides valuable clues. Some lumps feel soft and compressible, while others are firm or even hard to the touch. Mobility is equally important, as lumps that move freely under the skin are often less concerning than those that feel fixed or attached to underlying structures. In addition, veterinarians assess growth rate, color changes, and whether the lump causes pain, irritation, or inflammation.

One of the biggest challenges is that different types of lumps can feel very similar during a physical exam. A soft, movable lump may suggest a benign lipoma, but some malignant tumors can present in a similar way, especially in early stages. Likewise, inflamed cysts or abscesses can feel firm and be mistaken for more serious masses. Because of this overlap, it is not possible to diagnose a lump based on appearance or touch alone.

Common categories of lumps in dogs include lipomas (fatty tumors), cysts, benign and malignant tumors, warts, abscesses, hematomas, skin tags, and enlarged lymph nodes. While many of these are harmless, every new or changing lump should be evaluated to ensure nothing more serious is developing. Not all lumps require immediate veterinary attention, but regular checks of your dog's skin are important to catch any changes early.

Fatty tumors (lipomas)

Soft, slow-growing lumps made of fat cells, known as lipomas, are benign tumors. They can appear anywhere on a dog's body, including the chest, abdomen, legs, back, tail, head, and neck.

Cysts

Fluid-filled sacs that develop beneath the skin, cysts may appear as small bumps under the skin. Some cysts form when a hair follicle becomes blocked, leading to a buildup of material under the skin. If a cyst becomes infected, antibiotic treatment may be required to manage the infection and prevent further complications.

Benign tumors and malignant tumors

Abnormal growths can be benign or malignant. Some tumors are serious tumors, including cancerous tumors and malignant tumors. Benign tumors are typically slow-growing, well-defined, and do not spread to other parts of the body, though they can still be causing discomfort depending on their size or location and may need attention if they affect your dog's quality of life. In contrast, malignant tumors tend to grow rapidly, invade surrounding tissues, and may metastasize to distant organs. If a lump is diagnosed as malignant, surgical removal is often necessary to prevent spreading. Because some malignant tumors can initially resemble harmless lumps, any new or changing mass should always be evaluated by a veterinarian to ensure early diagnosis and appropriate management.

Warts (papillomas)

Papillomas are a benign skin growth commonly found in young dogs, often appearing as small growths caused by viral infections.

Abscesses

Infected pockets of pus caused by bacteria. After draining the abscess, veterinarians may prescribe antibiotics to treat the infection and prevent it from spreading or recurring.

Hematomas

Blood-filled swellings or inflammed bruising caused by trauma.

Skin tags

Harmless small flaps of skin that often appear in older dogs, skin tags are overgrowths of connective tissue within the skin. While many lumps are harmless, no lump should be ignored. Early evaluation gives your veterinarian the best chance of identifying a problem quickly.

Enlarged lymph nodes

Enlarged lymph nodes in dogs (lymphadenopathy), also known as swollen lymph nodes, can occur for several reasons, most commonly as a response to infection, inflammation, or immune stimulation, but they may also be associated with more serious conditions such as cancer, particularly lymphoma. Because of their size, shape, and location, these swollen nodes are often mistaken for growths like lipomas, cysts, or other tumors.

Lipomas (Fatty Tumors)

Lipomas are one of the most common lumps found in dogs, especially in middle aged and senior dogs. These tumors are benign growths made of fat cells and rarely spread to other organs or tissues. Lipomas typically feel soft and squishy, move easily under the skin, grow slowly, and are painless.

They are usually found on areas such as the chest, abdomen, legs, or armpits. Some dogs develop only one lipoma, while others may develop multiple fatty tumors over time.

Certain dogs have a higher risk, including overweight dogs and older dogs. Some breeds like Labrador Retrievers, Golden Retrievers, Doberman Pinschers, and Miniature Schnauzers are also prone to developing lipomas.

Are Lipomas Dangerous?

In most cases, lipomas are not dangerous and do not require removal. However, their size and location can sometimes make them problematic. Large lipomas may interfere with movement, particularly if they develop near joints or in areas where they rub against surrounding tissue. In rare cases, a type known as an infiltrative lipoma can grow into nearby tissues, making it more difficult to remove and potentially more invasive.

Treatment

Management of lipomas typically involves monitoring their size and growth over time. Veterinarians often recommend measuring and recording any changes to ensure they remain stable. Lipomas that become large, restrict mobility, or cause discomfort are often best treated by being surgically removed, as surgical removal is often the best treatment for lumps that are bothersome or growing (Rai & Chandrapuria, 2015). Maintaining a healthy weight may also help reduce the likelihood of developing additional lipomas. Treatment options include monitoring, having the lump surgically removed, and/or weight management.

Cysts

Cysts are another common type of lump in dogs and are generally benign. They are closed sacs that can be filled with fluid, keratin, or other material, and they often develop when hair follicles or skin glands become blocked (Adedeji et al., 2017).

There are several types of cysts seen in dogs. Sebaceous cysts are among the most common and form when oil-producing glands become obstructed. Follicular cysts develop around hair follicles, while dermoid cysts are rare congenital abnormalities present from birth.

Signs of a Cyst

Cysts typically appear as round, well defined lumps beneath the skin and are often slow growing. They may feel firm or slightly fluctuant, depending on their contents. In some cases, cysts can rupture and release a thick, white, or gray material that may have a strong odor. This material is often mistaken for pus, but it is usually composed of keratin rather than infectious debris.

Are Cysts Dangerous?

Most cysts are benign and harmless, but they can become infected, inflamed and/or irritated from scratching. It is important that pet owners avoid attempting to squeeze or “pop” cysts at home, as this can introduce infection and worsen inflammation. Proper veterinary evaluation ensures that the lump is correctly identified and managed safely.

Treatment

While most cysts are harmless, they can become problematic if they become inflamed, infected, or repeatedly rupture. In these situations, the surrounding tissue may become red, swollen, and painful. Veterinary treatment may include antibiotics if infection is present, as well as drainage or surgical removal in more persistent cases.

Mast Cell Tumors

Mast cell tumors are one of the most common malignant skin tumors in dogs and are known for their highly variable appearance. Mast cell tumors are the most common malignant tumors seen in dogs. These tumors originate from mast cells, which are part of the immune system and play a role in allergic and inflammatory responses (Garrett, 2014). Mast cell tumors can be irregularly shaped, making them sometimes difficult to identify visually.

Why Mast Cell Tumors Are Concerning

One of the reasons mast cell tumors are particularly concerning is their ability to release biologically active substances such as histamine. When this happens, it can lead to swelling, redness, itching, ulceration, and even systemic signs such as vomiting or gastric ulcers in more severe cases.

Mast cell tumors are often referred to as “the great pretender” because they can mimic many other types of lumps. They may appear as small, soft masses or as firm, raised lesions. Some may look red or ulcerated, while others appear relatively normal. A hallmark feature is that they can change in size, sometimes swelling rapidly and then decreasing again, which can be misleading for pet owners.

Certain breeds are more predisposed to developing mast cell tumors, including Boxers, Bulldogs, Boston Terriers, Labrador Retrievers, and Pugs. However, they can occur in any dog.

Treatment Options

Because of their unpredictable nature, early diagnosis is critical. Treatment typically involves surgical removal, often combined with additional therapies such as radiation, radiation therapy, chemotherapy, or targeted medications depending on the tumor’s grade and stage. Early detection and intervention significantly improve the chances of successful management.

Warts (Canine Papillomas)

Warts, or papillomas, are benign growths caused by the canine papillomavirus. They are most commonly seen in young dogs or those with developing or compromised immune systems. These growths are usually benign in nature. Dog warts often resemble small cauliflower shaped growths, rough bumps and pink or gray masses on the skin or mucosa (Munday and Knight, 2024).

They commonly appear around lips, mouth, eyelids, and paws.

Are Warts Contagious?

Yes. Papillomas can spread between dogs through:

• Direct contact

• Shared toys

• Grooming tools

Fortunately, they do not spread to humans.

Do Warts Require Treatment?

In most cases, warts resolve on their own as the dog’s immune system clears the virus. This process can take several weeks to months. Treatment is usually not necessary unless the warts become irritated, bleed, become infected, or interfere with normal functions such as eating or walking. In those cases, veterinary removal may be recommended.

When to Worry About a Lump

One of the most challenging aspects of finding a lump on your dog is knowing whether it requires urgent attention or simple monitoring. While many lumps are benign and remain stable over time, others may change in ways that indicate a more serious underlying condition.

Rapid growth is one of the most important warning signs. Lumps that increase in size over days or weeks should be evaluated promptly, as this can indicate aggressive behavior. Changes in shape, color, or texture are also concerning, particularly if a lump becomes irregular, ulcerated, or begins to bleed. Bleeding lumps can be a sign of ulceration or infection, and you should seek veterinary care if you notice any bleeding. Seek veterinary care if a lump starts to bleed, changes in size, or causes discomfort to your dog.

Pain is another important factor. While many benign lumps are painless, a mass that becomes sensitive or causes discomfort may indicate inflammation, infection, or invasion into surrounding tissues (Wells et al., 2024). Lumps that feel firmly attached to underlying structures rather than freely movable also warrant closer investigation.

Additional signs to watch for include discharge, ulceration, or the presence of enlarged lymph nodes, which may feel like firm swellings under the jaw, in front of the shoulders, or behind the knees. Systemic symptoms such as lethargy, weight loss, or decreased appetite may further indicate that a more serious process is occurring. If you notice any of these concerning symptoms, seek veterinary care promptly for a professional evaluation.

A commonly used guideline is that any lump larger than one centimeter, present for more than one month, or continuing to grow should be examined by a veterinarian. Ultimately, when in doubt, it is always safest to have a lump evaluated early rather than waiting for changes to occur.

You can read up about other types of fatty lumps (both malignant or benign) not covered in this article here.

Why Early Detection Matters when dealing with Cancerous lumps

Some tumors that appear harmless may actually be cancerous. Early diagnosis improves the chances of successful treatment (Pengram et al., 2020).

Regular monitoring of your dog for lumps during grooming or petting sessions, combined with preventive measures such as routine check-ups, is essential for early detection. We have put together another post that specifically deals with proactive monitoring. Timely veterinary care ensures that any changes are assessed promptly, leading to better treatment outcomes and improved pet health. For more information on

Diagnosis

Veterinarians use several tools to determine what a lump is and whether it requires treatment. Diagnostic tests for pet lumps may include fine needle aspiration, biopsy, and microscopic examination, which help identify the nature of the lump and guide treatment decisions (Meuten et al., 2021).

Physical Examination

The first step is a thorough physical exam where the veterinarian evaluates size, texture, mobility, location and pain level.

During this exam, the veterinarian will carefully check the dog's body, including common locations such as the back, legs, and head, for any lumps or bumps.

Fine Needle Aspiration (FNA)

This is one of the most common diagnostic tools. Veterinarians often use fine needle aspiration (FNA) to diagnose lumps on dogs by taking a small sample of cells from the growth.

A small needle is inserted into the lump to collect cells, which are then examined under a microscope. This test is quick, minimally invasive and often performed without anesthesia

If the lump discharges fluid or if FNA is inconclusive, veterinarians may use an impression smear. This involves pressing a microscope slide onto the lump to collect cells or fluid, which are then stained and examined to aid diagnosis.

Biopsy

If more information is needed, a biopsy may be performed. This involves removing a piece of the lump or the entire mass and sending it to a laboratory.

Biopsies provide a definitive diagnosis.

Imaging

In some cases, imaging tests may be recommended, including:

• X-rays

• Ultrasound

• CT scans

These help determine whether the tumor has spread or affects deeper structures, and can also show if the tumor has metastasized to other organs. Imaging is especially useful for detecting internal tumors that may not be visible on the surface.

Natural Support Options

Natural support options can help maintain overall health and support the immune system (Zaine et al., 2014). However, they should never replace veterinary care, especially when cancer is suspected.

Always consult your veterinarian before starting any new supplement or remedy.

Nutrition and Weight management

A balanced, high quality diet supports overall health and immune function. Many veterinarians recommend high quality protein, omega 3 fatty acids and antioxidant-rich foods (Laflamme, 2006).

Maintaining a healthy weight may also reduce the risk of certain tumors.

Omega-3 Fatty Acids

Omega 3s from fish oil may help support skin health, immune function and inflammation balance (Bauer, 2011).

These fatty acids are often used as supportive therapy for dogs with skin issues or tumors.

Medicinal Mushrooms

Certain mushrooms have been studied for their immune supporting properties, including Turkey tail, Reishi, Shiitake and Chaga (Chang and Wasser, 2012). Tremella, a lesser known antitumoral fungus (usually used in skin care formulations) is also a great addition to a medicinal mushroom regimen (Wu et al., 2019). They contain compounds such as beta glucans that may help support immune health. For more information on medicinal mushroom supplementation, you can click here.

Turmeric

Turmeric contains curcumin, a compound known for its antioxidant and anti-inflammatory properties (Silva et al.,2025).

Some pet owners use turmeric as a supplement for general wellness.

Herbal Support

Certain herbs are sometimes used in holistic veterinary medicine, including Milk thistle (liver support) (Scanlan, 2014) and Astragalus (immune support) (Clemons, 1997). These should always be used under professional guidance with a holistic vet.

Stress Reduction

Chronic stress may affect immune health. Dogs benefit from regular exercise, mental enrichment, consistent routines and quality bonding time with owners (Zapata et al., 2023).

Monitoring Lumps at Home

Pet owners can play an important role in monitoring their dog’s health.

Helpful tips include:

• Check your dog monthly for new lumps

• Measure existing lumps and record their size

• Take photos to track changes

• Note growth or color changes

• Practice regular monitoring to detect any changes early

Keeping a simple lump journal can help your veterinarian identify changes more easily.

Keep in mind

Discovering a lump on your dog can feel scary, but it’s important to remember that many lumps are harmless. Conditions such as lipomas, cysts, and warts are common and often manageable. Dogs are not the only companion species that develop lipomas or fatty lumps. You can find more information on lumps and bumps in cat and other species here.

However, some lumps can be serious, including mast cell tumors and other cancers we will briefly mention. Examples of more serious conditions include melanomas. These can be aggressive and are often darkly pigmented. Other examples, like squamous cell carcinomas are a type of skin cancer that can develop in areas of the dog's skin exposed to sun exposure, such as the nose, lips, and eyelids. Sun exposure is a known risk factor for certain skin tumors in dogs, including angiosarcomas and haemangiomas in addition to carcinomas. Tumors of blood vessels, such as haemangiomas, may appear as red or purple lumps on the dog's skin. Perianal adenomas are benign tumors commonly found around the anus in older, unneutered male dogs. Histiocytomas are small, red, button-like bumps that are usually benign, often found in young dogs less than 2 years of age, and may resolve on their own. In cases where tumors recur or cannot be surgically removed, radiation treatment may be considered as an additional therapy.

Monitoring pet lumps on your dog’s skin and dog’s body is crucial, as changes in size, shape, or appearance may signal a need for veterinary attention. Regularly checking your dog for new growths across all areas of the dog's body can help with early detection and treatment.

By staying observant, maintaining regular veterinary checkups, and supporting your dog’s overall health, you can help ensure your pet lives a long, happy life.

When in doubt, remember a simple rule: any new lump deserves attention.

Your dog relies on you to notice changes, and early action can make all the difference.

References

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Chang, S. T ., & Wasser, S. P . (Eds.). (2012). The role of mushrooms in the management of metabolic disorders: antioxidants and anti-inflammatory activities. CRC Press.

Clemmons, R. M. (1997). Integrative treatment of cancer in dogs. University of Florida.

Garrett, L. D. (2014). Canine mast cell tumors: diagnosis, treatment, and prognosis. Veterinary Medicine: Research and Reports, 49-58.

Laflamme, D. P. (2006). Understanding and managing obesity in dogs and cats. Veterinary Clinics: Small Animal Practice, 36(6), 1283-1295.

Meuten, D. J., Moore, F. M., Donovan, T. A., Bertram, C. A., Klopfleisch, R., Foster, R. A., ... & Whitley, D. (2021). International guidelines for veterinary tumor pathology: a call to action. Veterinary pathology, 58(5), 766-794.

Munday, J. S., & Knight, C. G. (2024). Papillomaviruses and papillomaviral disease in dogs and cats: A comprehensive review. Pathogens, 13(12), 1057.

Pegram, C. L., Rutherford, L., Corah, C., Church, D. B., Brodbelt, D. C., & O'Neill, D. G. (2020). Clinical management of lipomas in dogs under primary care in the UK. The Veterinary Record, 187(10), e83.

Rai, S., & Chandrapuria, V. P. (2015). Surgical management of lipoma in a dog. Indian Journal of Canine Practice Volume, 7(1).

Scanlan, N. (2014). Cancer biology and implications for complementary and alternative veterinary therapies.

Silva, T. O. D., Calheiros, L. G. R. D. M., Barbosa, F., Morrone, F. B., Rockenbach, L., Lainetti, P. D. F., ... & Laufer Amorim, R. (2025). Antitumor Effect of Curcumin, D6 Turmeric, and Hydrochloride Mitoxantrone on Canine and Human Urothelial Cancer Cells. Animals, 15(11), 1589.

Wells, G., Young, K., Haskell, M. J., Carter, A., & Clements, D. (2024). Mobility, functionality and functional mobility: A review and application for canine veterinary patients. The Veterinary Journal, 305, 1-8.

Wu, Y. J., Wei, Z. X., Zhang, F. M., Linhardt, R. J., Sun, P. L., & Zhang, A. Q. (2019). Structure, bioactivities and applications of the polysaccharides from Tremella fuciformis mushroom: A review. International journal of biological macromolecules, 121, 1005-1010.

Zaine, L., Monti, M., Vasconcellos, R. S., & Carciofi, A. C. (2014). Immunomodulatory nutraceuticals with potential clinical use for dogs and cats.

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