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Bumps and Lumps on Dogs’ Tails: 7 Causes & Treatment

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Bumps and lumps on dogs’ tails can be many things, including lipoma, cancer, cysts, or something else. Embedded ticks can also look like dark moles or bumps. Other times, skin infections lead to bumps on dogs’ skin, including the tail. Contact the vet if your pet develops bumps and lumps on its tail.

Pet owners will find lumps or bumps on their dogs at some point. Dogs get a lot of skin bumps throughout their lives, especially when they get older.

Lumps and bumps have various shapes and sizes and develop all over the body, including the tail. 

A bump on your dog’s tail can be severe (such as cancer) or less severe (such as a skin infection or lipoma).

In this article, you will learn why lumps and bumps appear on dogs’ tails, what to do, and much more.

Always contact the vet when you find a lump or bump on your dog’s tail.

Why Does My Dog Have a Bump on Its Tail?

Bumps on dogs’ tails appear for many reasons, the most common being harmless lipomas. Other reasons for the development of lumps and bumps on dogs’ tails include cancer, skin infections, cysts, warts, abscesses, or parasites.

Bumps, lumps, and nodules are the most common growths that appear on dogs’ skin, including the tail. 

They have multiple origins. Depending on the origin, bumps can have:

  • Different sizes
  • Different shapes
  • Different colors

Lumps and bumps on dogs’ tails are usually benign, meaning non-cancerous. But, there are cases in which they are cancerous tumors.

This is why it’s important to always contact the vet.

Here’s what the bumps on your dog’s tail can be:

  • Lipoma
  • Tumor
  • Cyst
  • Embedded tick
  • Skin infection (folliculitis)
  • Abscess
  • Wart

Take your pet to the vet if a bump or lump appears on its tail. Although the majority of lumps and bumps on dogs’ tails are harmless, it is better to be safe than sorry.

1. Lipomas

Lipomas on dog's tail

Lipomas are the most common bumps found on dogs and their tails. These should not create a cause for concern in general.

A lipoma is a benign tumor that is generally nothing to worry about. These are growths of fat cells covered by a thin capsule, usually found under the skin. They are the most common non-cancerous soft tissue growths and commonly occur in older dogs.[1]

Lipomas are most often found on the body, neck, legs, and armpits, but also on the tail and in other areas.

They are a tumor that grows over time. If you notice a growth appear overnight, it is unlikely to be a lipoma.

There are three common causes of lipomas:

  • A poor diet
  • Use of antiparasitic products with chemical substances
  • A bad living environment (especially if herbicides or pesticides are present)

The symptomatology of lipomas is neither specific nor varied. Lipomas are soft to the touch, with a texture similar to bread dough.

They are also mobile. If you take it in your hand, you can pick it up. Lipomas can be painful if they press on nearby nerves or contain many blood vessels.

2. Tumors

Tumor on dog's tail

Another reason why dogs develop bumps and lumps on their tails are tumors.

Cancerous tumors appear as bumps or lumps on dogs’ tails and take many forms: [2]

  • Mast cell tumors
  • Squamous cell carcinomas
  • Malignant tumors of hair follicles (trichoepitheliomas)
  • Sebaceous tumors
  • Soft tissue tumors (sarcomas)

Squamous cell carcinoma is a type of tumor caused by sun exposure.[3] This type of cancer appears on the skin and/or mouth. These tumors can have a pink or reddish color and a “raw” appearance. 

The most common locations are the abdomen, head, back, and legs, but this type of cancer can also appear on the ear or tail.

Trichoepitheliomas are benign tumors that can become malignant (i.e. cancerous) in rare cases. They are found on the back, shoulders, flank, tail, and limbs of dogs.[4]

The symptomatology of cancerous tumors on the tail is similar to that of lipomas. The major difference is that these lumps are hard and immovable.

In addition, they ulcerate and bleed more often than lipomas.

3. Cysts

Cysts appear when hair follicles become clogged with sebum. They are round, firm, and mobile bumps. They are harmless and shouldn’t be a reason for concern.

4. Embedded Tick

Embedded Tick on dog's tail

A bump can be an embedded tick. These are often mistaken for growths on dogs’ tails. They look more like moles or pedicled growths, such as warts.

In some cases, ticks embed themselves into dogs’ skin by sticking their heads and mouths under the skin. 

This happens when they attach to the skin to feed while dogs scratch or bite at them in an attempt to remove them.

These parasites never fully embed themselves. That’s why they are easily confused with moles, warts, or dark skin tags.

Ticks that are not engorged are easier to differentiate from growths on the skin because their legs are visible.

Before extracting the tick from your dog’s tail, make sure that it is not a skin formation.

5. Skin Infections (Folliculitis)

Skin Infections dog's tail

Folliculitis usually occurs when the hair follicles become infected with bacteria, especially Staphylococcus. It can also occur due to viral or fungal infections, parasites, trauma, and certain systemic diseases.

Folliculitis is a skin disease that causes inflammation of the hair follicles. It is caused by certain bacteria. Dogs with this disease develop red, pus-filled bumps on the skin called papules. 

Because of these bumps, your dog can suffer irritation, which causes excessive itching. Folliculitis can appear all over the body, including the tail. 

There are many causes that lead to folliculitis:[5]

  • Bacterial, viral, or fungal infections
  • Parasites
  • Trauma
  • Systemic diseases

The main signs of folliculitis in dogs as follows:

  • Redness
  • Swelling
  • Itchiness and scratching
  • Hair loss
  • Small bumps
  • Hyperpigmentation
  • Pain in the affected areas

6. Abscesses

dog abscesses
Image Source

Abscesses in dogs can appear unexpectedly. They are usually covered by hair, which makes them difficult to detect.

Abscesses usually appear after trauma, such as bites, perforations, or injuries that break the skin. They are pockets of pus that can appear in and on the body, including the tail.

They are painful, warm to the touch, firm, or pasty. 

If the abscesses break, greenish-yellow and foul-smelling pus will come out.

7. Warts

dog Warts
Image Source

Papillomas or warts are skin growths of viral origin with a pediculate shape. This condition is contagious and can be transmitted to other dogs.

Papillomavirus has an incubation period of 1-2 months. The condition usually goes away on its own two months after it occurs. 

Warts caused by papillomavirus are white, pink, or dark in color, pedunculated, and with a cauliflower-like shape.[6]

In rare cases (in old dogs) warts can also appear due to non-viral causes.

Why Does My Dog Have a Lump Under Its Tail?

There are also cases where the bump grows under the tail. In this case, it may be a tumor of the anal (perianal) glands. It can be benign (adenoma) or cancerous (adenocarcinoma).

Cancer of the anal glands in dogs shows the following symptoms:

  • Discomfort in the area around the anus (perianal region)
  • Anal secretions
  • Dogs drag their rear on the floor (spinning in a circle)
  • Dogs will constantly lick their perianal area
  • Straining during defecation
  • Constipation
  • Obvious growth in the anal region

 How to Identify Dangerous Lumps

Here is what to take into consideration when you find a lump or bump on your dog’s body:

Lump aspectsWhat to look for
Growth speedIf it appeared “overnight”, you need to go to the vet.
ShapeSmooth and round lumps are usually a cause of concern.
Color/appearanceBlack, pink, and ulcerated lumps are usually a cause of concern.
Feel to the touchImmovable lumps should cause concern.
About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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