Lumps on Dogs

Key Takeaways

• Regularly examine your dog for lumps and consult a vet promptly to determine if they are benign or malignant.

• Common lumps in dogs, such as lipomas, skin tags, and warts, are often benign but may require monitoring or treatment.

• A healthy lifestyle, regular vet check-ups, and a clean environment can help prevent certain types of lumps in dogs.

Lumps on dogs are growths on or under the skin that can vary in appearance, location, underlying causes, and severity. While they're common, it can be startling to discover one on your dog when casually petting them or going about your regular grooming routine.

There are several different types of lumps, and although some may be malignant (cancerous), not all are. Some of the most common are benign (non-cancerous) and can even go away on their own without treatment. Knowing the differences between various lumps, how to check your dog for growths, and what to do if you happen to find any can help get your dog the veterinary attention needed to diagnose and treat them as soon as possible.

Here's what you should know about lumps on dogs.

Common Types of Lumps on Dogs

While there are many different types of lumps that can be found on dogs, here are the most common:

Lipomas (fatty lumps)

Lipomas are common, benign tumors made up of fatty tissue.1 These fatty tumors are generally soft, sometimes thin, and able to be felt and moved under a dog’s skin. Lipomas can vary in size, and in some cases, they may grow to become very large. They are often seen in older dogs, particularly overweight female dogs, typically appearing on the trunk and tops of the legs. Certain breeds can also be predisposed to developing lipomas, such as Labrador retrievers, miniature schnauzers, Doberman pinschers, and mixed breeds.2

Although lipomas are not cancerous or able to spread, they can grow larger and may cause dogs discomfort if left untreated. Liposarcomas, on the other hand, are malignant tumors but are rare in dogs and other pets.

Skin Tags and Warts

Skin tags are common, fleshy growths. These will usually resemble a stalk-like growth that’s covered by a wart-like surface. Their causes can include friction, overactive fibroblast cells, and excessive bathing. While large breeds and older dogs can be more prone to developing skin tags, they can occur in any breed of any age.

Warts, or papillomas, are also common and generally affect dogs two years old and younger. These have a round, lumpy, and cauliflower-like appearance. Different papillomaviruses can cause these tumors in dogs of all ages, affecting various areas, such as the mouth, skin, feet, genitals, eyelids, or tissue. Dogs contract the virus through contact with an infected dog or their environment, like bedding, toys, or food and water bowls.3 The virus enters the body through cuts, bites, or moist skin.

Although skin tags and warts may look alarming, both are generally harmless.

Button Tumors

A button tumor, or histiocytoma, is a skin growth that is raised, smooth, red, and hairless, giving the appearance of a button. Histiocytomas originate in the Langerhans cells,4 which are responsible for protecting the body from bacteria, fungi, or pollen. When these cells become tumorous, they produce a growth as well as cause inflammation. They can show up anywhere but are usually on the head, ears, neck, or limbs. Despite their appearance, they are non-cancerous and painless. Young adult dogs are more likely to develop button tumors, as well as certain breeds including boxers, Boston terriers, English bulldogs, greyhounds, and Scottish terriers.

Histiocytomas can heal on their own within a few months without treatment. However, in some cases, they may require removal through surgical removal or cryosurgery depending on the growth’s size and location.

Cornifying Epitheliomas

Cornifying epitheliomas are benign growths that tend to affect middle-aged dogs. These layered lumps stick up from the skin’s surface, resembling a horn, and other times, simply cornified cysts. Also known as keratoacanthoma and infundibular keratinizing acanthoma, these lesions likely occur from a hair follicle, much like with human keratoacanthoma. Cornifying epitheliomas can show up anywhere on a dog’s body but are commonly seen on the back, tail, and legs.

Treatment is considered optional if cornifying epitheliomas pose no issue of discomfort or infection to a dog. While these can be surgically removed, there is a chance they can come back.

Identifying and Assessing Lumps on Dogs

It's important to be able to understand what a lump is and how to differentiate between the various kinds and other types of growths. Knowing what to look for can be helpful, ultimately for your dog's health and well-being.

Signs and Symptoms

When identifying and assessing lumps on your dog, check for the following signs and symptoms5:

• Bleeding from the mouth, nose, or other body openings

• Lumps, bumps, or discolored skin

• Unexplained swelling, heat, pain, or lameness

• A visible mass or tumor

If you notice any unusual growths that have developed, take photos and note their location, size, and firmness and consult a veterinarian promptly.

When To Be Concerned

Because lumps and bumps are either benign or malignant, it's crucial to know which signs warrant immediate veterinary help.

Signs of a potentially cancerous or serious condition may include:

• Abnormal swelling that persists or continues to grow

• Bleeding or discharge from any body opening

• Decreased appetite

• Difficulty eating or swallowing

• Difficulty in breathing, defecating, or urinating

• Hesitation or inability to exercise

• Limping or stiffness

• Smelly odor

• Sores that do not heal

• Weight loss

Self-Examination Techniques

Regularly giving your dog a thorough head-to-tail exam at home is a great way to keep up with their general wellness and detect anything unusual early on.

Here’s a step-by-step on how to check your dog for lumps6:

1. Firmly—but gently—run your hands along their entire body, starting from the top of their head to the end of their tail. Make sure to feel for lumps in areas that can potentially be overlooked, like under the armpits, over the top of the feet, between the toes, around the groin, and behind the ears.

2. Feel through your dog’s fur, as opposed to just over their coat.

3. If you feel a lump or bump, check if your dog reacts to them being touched to indicate any signs of pain or discomfort.

4. Take note of the size, shape, firmness, and texture of the lump, its location, and any other accompanying signs.

Noticing a lump on your dog is stressful for any pet parent. Though it may be tempting to try to diagnose and treat them yourself, it’s always best to consult a veterinary professional right away for a proper diagnosis and treatment.

Treatment and Management of Lumps on Dogs

Treatment for lumps will depend on the type, its size and location, whether it's posing issues to your dog, and whether it's benign or malignant. Due to the risk of certain lumps potentially being cancerous, it's best to take a proactive approach to your dog's treatment.

Veterinary Evaluation and Diagnosis

No matter how big or small the lump on your dog, it’s important to consult a vet—especially if it’s larger than one centimeter, or pea-sized,7 and present for a month. Your vet will perform a physical examination and additional diagnostics so they can determine what kind of lump it is and develop a treatment plan.

There are several ways a vet can find out what the lump is, whether it’s malignant or benign, and how to properly treat it. These options include:

• Cytology: A process in which some cells are withdrawn from a mass to examine under a microscope. This helps determine what type of tumor the lump is, as well as a diagnosis for particular types of cancer if it's malignant.

• Biopsy: A process in which a tissue sample is taken from the neoplasm to examine under a microscope. This confirms the diagnosis and determines whether the lump is benign or malignant.

• Advanced imaging (e.g. CT scan, MRI, PET scan): These may be used in conjunction with cytology or biopsies to better understand the tumor’s location and possible treatment options.

Non-Surgical Treatment Options

Non-surgical treatment can be appropriate for certain kinds of lumps.8 These methods may include:

• Monitoring for any changes

• Medication

• Removal using freezing or laser treatments

• Immunotherapy

• Radiation therapy

• Chemotherapy

Follow your vet’s recommendations to ensure your dog's lumps are successfully treated.

Surgical Removal

Surgical removal may be necessary in cases where lumps are causing pain, bleeding, irritation, or infection, growing larger, or malignant. If lumps are benign, a smaller surgery will be performed.

Potential risks involving surgical removal include:

• Surgery complications, including a post-operative infection

• Pain and discomfort for a short or long period of time

• May inhibit normal function in limbs or organs where the lump was location

Potential benefits involving surgical removal include:

• May lead to a complete cure and disease-free life

• Improved quality of life

• Prolonged life

• Reduced pain

• Least costly compared to other forms of treatment

• Fewest side effects compared to other forms of treatment

A dog who undergoes surgery will need to rest for two weeks to fully heal.9 Provide them with a quiet space to sleep and rest. Make sure they wear a cone at all times to prevent any licking or chewing of the incision, administer any medication your vet prescribed to reduce pain, and treat the incision. Monitor your dog and check their incision for redness, heat, swelling, discharge, or openings. Contact your vet right away if you notice any concerning signs.

Preventive Measures and Care

Although not all lumps in dogs can be prevented, the good news is that some can. Here's how you can help prevent certain types of lumps from developing:

Maintaining a Healthy Lifestyle

A healthy diet and active lifestyle can be beneficial in preventing some lumps, like lipomas.10 By maintaining a healthy weight, certain growths can shrink and may not reoccur in the future. Consult your vet for dog food recommendations and physical activities that best suit your dog's individual needs.

Regular Check-Ups and Screenings

In addition to checking for new lumps and bumps at home, it's essential to schedule regular veterinary check-ups and screenings at least annually. Your vet can check your dog's health status and provide further guidance on preventative care if necessary.

Environmental Considerations

Although it's unclear why some lumps in dogs occur, a few can develop due to the environment.11 Factors that may contribute to the development of certain types of lumps include exposure to viruses (e.g. papillomavirus) and carcinogens (e.g. paints, asbestos, solvents, herbicides). Maintain a clean environment and avoid using potentially harmful household products to reduce the risk of lumps or any other health condition(s).