Is That Red Bump Dangerous? When To Call A Vet

Dermal Hemangiomas in Dogs: Causes, Diagnosis, Treatment & Prognosis (Complete Guide)

An SEO‑optimized, long‑form veterinary blog

Dermal hemangiomas are among the most frequently diagnosed benign skin tumors in dogs. While the word “tumor” can be alarming, these growths are typically non‑cancerous and highly treatable. Still, because they can resemble more dangerous conditions—especially hemangiosarcoma—early evaluation and proper diagnosis are essential.

This comprehensive guide explains what dermal hemangiomas are, why they develop, how veterinarians diagnose them, and what treatment and prognosis look like for affected dogs.

What Is a Dermal Hemangioma?

A dermal hemangioma is a benign tumor of blood vessels located within the skin. These tumors arise from endothelial cells—the cells that line blood vessels. They are non‑invasive, slow‑growing, and do not metastasize.

Dermal hemangiomas are different from:

• Subcutaneous hemangiomas – located deeper under the skin

• Hemangiosarcomas – malignant, aggressive blood‑vessel cancers

• Vascular malformations – congenital abnormalities rather than tumors

According to Veterinary Partner, hemangiomas are benign vascular tumors that may be linked to solar (UV) radiation, especially when they occur on lightly pigmented, sparsely haired skin.

What Do Dermal Hemangiomas Look Like?

These tumors can appear in several forms:

• Small, red to purple bumps

• Dark, bruise‑like lesions

• Raised, blood‑filled nodules

• Occasionally ulcerated or crusted areas

They are most common on:

• The belly

• The inner thighs

• The chest

• Other areas with thin hair and light pigmentation

A retrospective study of 212 dogs found that dermal hemangiomas and hemangiosarcomas were significantly more common on ventral glabrous (hairless) skin, supporting the link to sun exposure.

Which Dogs Are Most at Risk?

While any dog can develop a dermal hemangioma, certain factors increase risk:

1. Coat Color & Skin Pigmentation

Dogs with light skin and short coats are more susceptible, especially those who sunbathe frequently.

Breeds commonly affected include:

• Whippets

• Dalmatians

• Beagles

• Basset Hounds

• American Staffordshire Terriers

• Boxers

• Greyhounds

These breeds are overrepresented in solar‑induced hemangiomas.

2. Age

Most dogs are middle‑aged to senior at diagnosis.

3. Sun Exposure

Chronic UV exposure is a major contributor, especially for lesions on the belly and chest.

4. Genetics

Some dogs may have a genetic predisposition to vascular tumors.

Causes of Dermal Hemangiomas in Dogs

The exact cause is not fully understood, but research points to several contributing factors:

1. UV (Solar) Radiation

The strongest evidence links dermal hemangiomas to sun damage, especially in lightly pigmented dogs.

• UV light causes DNA damage in skin cells

• Damaged endothelial cells may proliferate abnormally

• Solar elastosis (sun‑damaged connective tissue) is often found near these tumors

Both Veterinary Partner and the retrospective study highlight UV exposure as a major factor.

2. Genetic Mutations

Spontaneous mutations in endothelial cells can lead to benign tumor formation.

3. Chronic Inflammation or Trauma

Repeated irritation may contribute to abnormal cell growth.

4. Age‑Related Cellular Changes

Older dogs accumulate more DNA damage over time.

Clinical Signs & When to Worry

Dermal hemangiomas may cause:

• A single or multiple skin bumps

• Bleeding or bruising if the mass ruptures

• Ulceration or scabbing

• Rapid enlargement after trauma

Most dogs show no systemic illness, which helps differentiate hemangiomas from malignant hemangiosarcoma.

However, because benign and malignant vascular tumors can look identical externally, every new skin mass should be evaluated.

How Veterinarians Diagnose Dermal Hemangiomas

1. Physical Examination

Your veterinarian will assess:

• Size, shape, and color of the mass

• Location (sun‑exposed areas raise suspicion)

• Whether the lesion is dermal or subcutaneous

2. Fine Needle Aspiration (FNA)

A small needle collects cells for microscopic evaluation.
However, FNAs often yield only blood, making them inconclusive for vascular tumors.

3. Biopsy or Surgical Removal

This is the gold standard for diagnosis.

A pathologist examines the tissue to determine:

• Whether the tumor is benign (hemangioma)

• Whether it is malignant (hemangiosarcoma)

• Whether surgical margins are clean

4. Imaging (If Needed)

If malignancy is suspected, your veterinarian may recommend:

• Chest X‑rays

• Abdominal ultrasound

• Bloodwork to check for anemia or internal bleeding

These tests help rule out internal hemangiosarcoma.

Treatment Options for Dermal Hemangiomas

1. Surgical Removal

The most common and effective treatment.

Benefits:

• Curative in most cases

• Prevents bleeding or ulceration

• Allows full histopathology

Veterinary Partner notes that once a benign hemangioma is removed, no further treatment is usually needed.

2. Cryotherapy or Laser Ablation

Useful for small, superficial lesions.

3. Sun Protection

Essential for dogs with solar‑induced hemangiomas:

• Limit midday sun exposure

• Use dog‑safe sunscreen on lightly pigmented areas

• Provide shade during outdoor time

4. Monitoring

If surgery is not immediately necessary, your veterinarian may recommend:

• Regular measurements

• Watching for changes in color, size, or ulceration

Prognosis for Dogs with Dermal Hemangiomas

The prognosis is excellent.

Key points:

• Dermal hemangiomas are benign

• They do not metastasize

• Surgical removal is typically curative

• Dogs return to normal activity quickly

However, dogs with solar‑induced hemangiomas may develop new lesions over time, especially if sun exposure continues.

Risk of Malignant Transformation

Rare, but possible.
One study documented a dermal hemangioma with areas of malignant transformation.

This is another reason why biopsy and monitoring are important.

Dermal Hemangioma vs. Hemangiosarcoma: Why It Matters

Because these tumors look similar, distinguishing them is critical.

FeatureDermal HemangiomaHemangiosarcomaBehaviorBenignMalignant, aggressiveSpreadDoes not metastasizeHigh metastatic potentialAppearanceRed/purple bump, may bleedSimilar appearanceTreatmentSurgery curativeSurgery + staging + oncology carePrognosisExcellentGuarded to poor

A biopsy is the only way to know for sure.

Prevention Tips for At‑Risk Dogs

While not all hemangiomas can be prevented, you can reduce risk:

• Limit sun exposure between 10 AM–4 PM

• Use dog‑safe sunscreen on belly, groin, and inner thighs

• Avoid shaving lightly pigmented dogs too closely

• Provide shaded outdoor areas

• Perform monthly skin checks

When to See a Veterinarian

Seek veterinary evaluation if you notice:

• A new skin bump

• A lesion that bleeds or bruises easily

• A mass that grows rapidly

• Multiple red or purple skin spots

• Any lump on a lightly pigmented, sun‑exposed area

Early diagnosis ensures the best outcome.

Final Thoughts

Dermal hemangiomas in dogs are common, benign, and highly treatable. With proper diagnosis and surgical removal, most dogs make a full recovery and live normal, healthy lives. Because these tumors can mimic more serious conditions, prompt veterinary evaluation is essential.

If you’ve noticed a red or purple skin lesion on your dog, book a dermatology consultation now. Our team can perform proper testing, confirm whether it’s a benign hemangioma, and recommend the right treatment plan.

Frequently Asked Questions About Dermal Hemangiomas in Dogs

What is a dermal hemangioma in dogs?
A dermal hemangioma is a benign tumor that forms from blood vessels in the skin. These tumors are usually small, raised growths that develop on areas of the body exposed to sunlight.

What do dermal hemangiomas look like in dogs?
Dermal hemangiomas often appear as red, dark red, or black skin nodules. They may be slightly raised and sometimes resemble small blood blisters or skin lumps.

Are dermal hemangiomas cancerous?
Dermal hemangiomas are benign tumors and are not cancerous. However, they can resemble malignant tumors such as hemangiosarcomas, so veterinary evaluation is important.

What causes dermal hemangiomas in dogs?
Sun exposure is believed to play a major role in the development of dermal hemangiomas. Dogs with thin hair coats or light-colored skin may be more susceptible.

Which dogs are more likely to develop dermal hemangiomas?
Dogs with short hair or light-colored skin are at higher risk. Breeds that spend a lot of time outdoors in the sun may develop these tumors more frequently.

Do dermal hemangiomas need to be removed?
Many dermal hemangiomas can be surgically removed if they grow larger, bleed, or become irritated. Your veterinarian may recommend removal to confirm the diagnosis.

Can dermal hemangiomas become malignant?
Dermal hemangiomas themselves are benign, but they can sometimes be difficult to distinguish from hemangiosarcoma without examination and biopsy.

How are dermal hemangiomas diagnosed in dogs?
Veterinarians typically diagnose these tumors through physical examination and may confirm the diagnosis with a biopsy or surgical removal followed by laboratory analysis.

Are dermal hemangiomas painful for dogs?
Most dermal hemangiomas are not painful. However, if they become ulcerated or irritated they may cause discomfort.

When should I see a veterinarian about a skin lump on my dog?
Any new skin lump or growth should be examined by a veterinarian to determine whether it is benign or potentially cancerous.

Related Dog Health Articles

You may also find these veterinary articles helpful:

• Dog Lump Under Skin
• Lipoma in Dogs
• Sebaceous Cyst in Dogs
• Dog Abscess
• Canine Papilloma Virus
• Histiocytoma in Dogs
• Hamartoma in Dogs
• Mast Cell Tumor in Dogs
• Dog Mammary Tumor
• Dog Skin Tumors