Old Dog Lumps and Bumps (Causes Explained)

Old Dog Lumps and Bumps: Common Causes

Lipomas (Benign Fatty Tumors)

Lipomas are one of the most common lumps found in senior dogs. These soft, moveable masses form under the skin as collections of fat cells that grow in size over time.

Although lipomas can become quite large, they are usually painless and harmless. Many older dogs develop multiple lipomas because age affects fat metabolism and cell repair.

These growths often appear on the chest, belly, or legs, and while they rarely interfere with normal movement, very large lipomas can limit mobility or become irritated by rubbing.

Lipomas can grow slowly over months or even years, and their soft, squishy texture distinguishes them from firmer or irregular masses that may signal more serious conditions.

Even though lipomas are benign, each new lump should be evaluated to ensure it is not a different type of tumor.

Read more: Old Dog Health Problems (What to watch for)

Sebaceous Cysts and Blocked Hair Follicles

Sebaceous cysts form when a hair follicle or oil gland becomes blocked, trapping fluid or thick material beneath the skin.

These cysts are common in older dogs because the skin becomes drier and more prone to blockage as dogs age. They often appear as round, firm bumps that may grow slowly or remain the same size for long periods.

Some cysts rupture on their own, releasing a cottage cheese–like substance, while others remain sealed.

Although these bumps are typically not painful, they can become inflamed or infected if irritated. Dogs may lick or scratch at them, increasing the risk of infection.

Sebaceous cysts are generally harmless but can look similar to more serious growths, so veterinary evaluation is always recommended.

Skin Tags, Warts, and Age-Related Skin Growths

Skin tags and warts become more common as dogs enter their senior years due to changes in skin elasticity and immune function.

These small, fleshy growths may dangle, protrude, or appear as rough, textured bumps on the face, body, or limbs.

Warts caused by viral papillomas are more common in younger dogs but can persist or reappear as the immune system weakens.

In senior dogs, many skin growths form simply as a result of aging and are generally harmless unless they grow rapidly, bleed, or interfere with grooming.

Dogs with thick coats often develop hidden skin tags that owners discover while brushing or bathing. While most of these growths are benign, any sudden changes in size or texture should be examined closely.

Abscesses or Infections Under the Skin

Abscesses occur when bacteria become trapped beneath the skin, forming a pocket of pus that swells and becomes warm, painful, or red.

Senior dogs may develop abscesses from minor wounds, insect bites, dental infections, or internal infections that spread through the bloodstream.

Older dogs are more vulnerable because their immune systems respond more slowly, allowing infections to grow before owners notice symptoms.

Abscesses often appear suddenly and can be tender to the touch. Some may rupture and drain, while others continue to swell. A dog may develop fever, lethargy, or loss of appetite due to infection.

Although abscesses are treatable, they can resemble tumors before they rupture, making veterinary evaluation important.

Mast Cell Tumors or Other Skin Cancers

Mast cell tumors are among the most common skin cancers in dogs and can appear as firm, raised, or irregular lumps.

Their appearance varies widely — some look like harmless bumps, while others grow aggressively or change shape.

Older dogs are at higher risk for cancerous growths because cell division becomes more error-prone with age. Mast cell tumors may swell and shrink unpredictably due to histamine release, and some become ulcerated or itchy.

Other cancers, such as melanoma, fibrosarcoma, or squamous cell carcinoma, also form lumps beneath the skin or at the surface. These tumors may feel firmer than lipomas and often grow more quickly.

Because cancer risk increases significantly in senior dogs, every unusual or fast-growing lump should be biopsied to determine its nature.

Lymph Node Enlargement Due to Illness or Disease

Sometimes what appears to be a lump is actually an enlarged lymph node. Lymph nodes swell when the body is fighting infection, inflammation, or cancer.

Senior dogs are prone to immune system changes that make them more susceptible to infections and lymphoma, a cancer of the lymphatic system.

Enlarged nodes may appear under the jaw, in the armpits, or behind the knees. These lumps feel firm and may grow rapidly, which can be alarming.

While some swelling resolves once the underlying issue improves, persistent or multiple enlarged lymph nodes require prompt evaluation to rule out serious disease.

Soft Tissue Sarcomas or Deep Tissue Tumors

Soft tissue sarcomas are slow-growing but invasive tumors that develop in muscle or connective tissue beneath the skin. They often feel like firm, fixed lumps rather than soft or moveable masses.

These tumors are more common in older dogs and can grow quietly for months before becoming noticeable. Because they grow inward as well as outward, they may not appear large on the surface even when they extend deep into surrounding tissue.

Dogs with these tumors may develop discomfort, limping, or difficulty moving if the growth interferes with normal muscle function.

Soft tissue sarcomas are concerning because they can recur even after removal, making early diagnosis essential.

Read more: Dog losing hair black spots on skin (What it means)

What to Do If Your Old Dog Has Lumps and Bumps

Start by examining the lump gently to understand its size, shape, and texture. Note whether it feels soft, firm, warm, or painful. Keep track of when the lump first appeared and whether it has grown or changed in shape.

Avoid squeezing or poking the lump, as irritation can cause inflammation or infection. Make your dog comfortable by keeping the area clean and preventing excessive licking or scratching.

Provide padded bedding if the lump is located where your dog regularly lies down. If the lump grows, changes color, becomes painful, or begins to ooze, schedule a veterinary exam promptly.

Senior dogs benefit from early evaluation because many conditions are easier to treat when diagnosed early. Even harmless lumps should be monitored regularly so you can detect any changes quickly.

When to Call or Visit Your Vet

Seek veterinary care if your old dog has lumps and bumps that show:

• Rapid growth or sudden enlargement.
• Bleeding, ulceration, or discharge.
• Pain when touched or pressure-sensitive swelling.
• Changes in color, texture, or shape.
• Multiple new lumps appearing at once.
• Swelling under the jaw, in the armpits, or behind the knees.
• Weight loss, lethargy, or decreased appetite.
• Difficulty walking due to lump location.
• Persistent licking or irritation of the lump.
• Any lump that appears suddenly or grows quickly.

All new or changing lumps in senior dogs should be evaluated.

Read more: Dog Panting and Itching At Night (Here’s why)

Key Takeaway

Old dog lumps and bumps are common and often benign, but some indicate infection, inflammation, or cancer that requires prompt attention.

By monitoring growths closely, seeking veterinary evaluation early, and supporting your dog’s comfort at home, you can help ensure your senior dog stays healthy, safe, and well cared for throughout their later years.