Finding bumps on your old dog’s skin can be alarming, especially when they appear suddenly or begin to grow.
Senior dogs commonly develop lumps, growths, and skin changes as they age — and while many are harmless, others require veterinary attention.
We outline the common causes of skin bumps in old dogs, what you can do at home, and when to seek veterinary help.
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Old Dog Bumps on Skin: Why It Happens
Bumps on an old dog’s skin are usually caused by benign growths, fatty tumors, cysts, warts, infections, allergic reactions, or occasionally cancerous tumors.
Senior dogs experience natural changes in the skin’s elasticity, immune function, and cell turnover, making them more prone to lumps and irregularities.
Some bumps are soft and movable; others are firm, raised, or inflamed. While many age-related bumps are harmless, changes in size, shape, or behavior often signal the need for veterinary evaluation.
Old Dog Bumps on Skin: Common Causes
Lipomas (Fatty Tumors)
Lipomas are one of the most common bumps found on old dogs. These soft, movable, non-painful masses form under the skin and are made of fatty tissue.
They typically grow slowly and can appear anywhere on the body — especially the chest, underarms, and belly.
As dogs age, their metabolism slows and fatty deposits form more easily, contributing to lipoma development.
Most lipomas are completely benign, but very large ones can restrict movement or rub against joints, causing discomfort.
Dog owners often worry when they feel a new lump, but lipomas usually have a smooth, soft, “squishy” feel.
Even so, every lump should be checked because cancerous tumors can sometimes mimic lipomas.
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Sebaceous Cysts
Sebaceous cysts are small, round bumps caused by blocked hair follicles or oil glands.
These bumps often:
• Feel firm
• Are located on the back, neck, or face
• Grow slowly
• Sometimes rupture and release thick, white material
In older dogs, the skin doesn’t shed as efficiently, making it more prone to clogged glands. A cyst can remain small for years or suddenly swell if irritated or infected.
When a cyst ruptures, it may ooze or scab over. Repeated rupture increases the risk of bacterial infection, leading to redness, pain, or swelling.
Warts and Skin Tags
Senior dogs frequently develop warts and skin tags due to slower immune response and accumulated skin stress.
These bumps are usually:
• Small and fleshy
• Rough or cauliflower-like
• Located on the face, legs, or eyelids
• Harmless unless irritated
Warts may appear singly or in clusters. Some develop where friction is common — such as under the legs or near collars — causing irritation or bleeding.
Older immune systems cannot suppress certain skin viruses as effectively, making warts more common with age.
Mast Cell Tumors
Mast cell tumors (MCTs) can appear as simple bumps but may be cancerous.
MCTs vary dramatically in appearance:
• Some are soft
• Others are firm or ulcerated
• They may grow quickly or stay unchanged for months
These tumors contain inflammatory cells that can release histamine, causing swelling, redness, or sudden growth. Old dogs — especially boxers, bulldogs, labs, and pugs — are at higher risk.
Because MCTs can resemble harmless bumps, it’s essential to have any lump checked.
Early diagnosis improves treatment options significantly.
Infected Hair Follicles or Skin Infections
Folliculitis, bacterial infections, and yeast infections can cause red, swollen bumps on the skin.
These bumps may:
• Be warm to the touch
• Ooze or form crusts
• Cause itchiness
• Appear in clusters
Old dogs have weaker immune responses, making them more prone to infection — especially if they already have allergies, arthritis, or chronic skin irritation.
Infections often occur on the belly, groin, back, or tail area. Constant scratching further damages the skin, creating more bumps and irritation.
Allergic Reactions or Dermatitis
Allergies to food, pollen, dust mites, grooming products, or insect bites can create raised bumps on a dog’s skin.
Senior dogs can develop allergies later in life, even if they never had them before.
Allergic bumps typically appear as:
• Red, raised welts
• Itchy or inflamed patches
• Localized swelling around the face or paws
If a bump appears suddenly after a new treat, bedding, or grooming product, an allergic reaction is likely. Chronic allergies can also lead to repeated irritation that forms bumps over time.
Histiocytomas or Benign Tumors
Although histiocytomas are more common in younger dogs, old dogs can still develop benign tumors that resemble them.
These bumps are typically:
• Red
• Raised
• Dome-shaped
• Non-painful
They may grow quickly at first but often stabilize. While usually harmless, any fast-growing lump should be examined.
Read more: Dog Excessively Itching (Here’s why)
What to Do If Your Old Dog Has Bumps on the Skin
Start by examining each bump gently. Check whether it’s soft, hard, warm, or painful.
Monitor size, shape, and texture regularly. A sudden change can indicate inflammation, infection, or cancer.
Keep the area clean — especially if the bump is near folds or hair-dense regions. Moisture increases the risk of infection.
Avoid squeezing or popping a bump.This can cause infection, pain, or scarring.
If your dog licks or scratches the bump often, use a cone or recovery suit to prevent irritation. Constant trauma worsens swelling and increases risk of infection.
Consider switching to fragrance-free shampoos or hypoallergenic grooming products.
Senior skin is more sensitive to chemicals and fragrances.
Provide a balanced diet with omega-3 fatty acids (vet-approved). These support skin health and reduce inflammation.
Take note of other symptoms like weight loss, lethargy, or increased thirst. These may indicate a deeper medical issue that correlates with skin changes.
Always get new bumps checked — the sooner you know what you’re dealing with, the easier it is to treat.
When to Call or Visit Your Vet
Seek veterinary care if your old dog has bumps on the skin and any of the following signs appear:
- If a bump grows rapidly, changes color, becomes firm, or ulcerates, a mast cell tumor or other cancer may be involved. Urgent evaluation is needed.
- If the bump is painful, warm, or leaking fluid, infection or inflammation is likely. Infected bumps worsen quickly without treatment.
- If your dog scratches or bites at the bump continually, the area can become damaged or infected. This makes treatment harder and more painful.
- If multiple bumps appear suddenly, this may indicate an allergic reaction or immune issue. Early intervention prevents worsening.
- If your dog has weight loss, decreased appetite, or lethargy along with skin bumps, internal disease may be progressing. These symptoms should not be ignored.
- If the bump is located near the mouth, genitals, or eyelids, these sensitive areas require careful evaluation. Growths here can cause discomfort or interfere with normal function.
- If your dog has a history of cancer or previous mast cell tumors, every new bump must be examined.
- Recurrence is common in some senior dogs.
Read more: Old Dog Behavior Change (When it matters)
Key Takeaway
Old dog skin bumps are often caused by benign growths like lipomas, cysts, or warts — but they can also signal infection, allergies, or cancer.
Because senior dogs experience more skin changes as they age, every new lump deserves attention.
With early evaluation, simple monitoring, and proper care, most bumps can be managed safely, ensuring your senior dog remains comfortable and healthy.