Do Benign Tumors Rupture In Dogs?

Benign tumors are abnormal growths that do not spread or invade nearby tissue. They are noncancerous growths that originate from normal cells in the body. Research shows that benign tumors are common in dogs, with a lifetime prevalence of 14.7 tumors per 1000 dogs. While benign tumors are noncancerous, they can still impact a dog’s health if they continue growing or rupture.

Ruptured benign tumors can have serious health consequences in dogs depending on the location, size, and type of tumor. Rupture may be spontaneous or due to trauma. Potential complications include significant bleeding, infection, tissue damage, pain, obstruction, and even death in some cases. However, the outlook can be good if the ruptured tumor is treated promptly. It’s important for dog owners to monitor benign tumors and be aware of signs of rupture so they can seek veterinary care right away.

Types of Benign Tumors in Dogs

Some of the most common types of benign tumors in dogs include:

Lipomas – These fat cell tumors are usually soft, movable lumps under the skin. They are one of the most common benign masses seen in dogs. Lipomas can develop anywhere on the body but are most often found on the chest, abdomen, upper legs, and armpits.

Sebaceous adenomas – These benign tumors of oil glands in the skin often appear as small bumps on the head, neck, and trunk. They are common in older dogs.

Melanocytomas – These pigmented skin tumors are usually black or dark brown. They can develop anywhere but are often seen on areas with little hair like the head, belly, and feet.

Histiocytomas – These benign growths of immune cells are mostly found on the head, ears, and limbs of young dogs under 3 years old. They usually disappear on their own within a few months.

Papillomas – These wart-like viral tumors are common on young dogs. They appear as small, cauliflower-like masses that can develop anywhere but are often seen around the mouth.

Cysts – Fluid-filled cysts can form benign masses under the skin. Common examples are sebaceous cysts of the oil glands and interdigital cysts between the toes.

Causes and Risk Factors

There are several factors that can increase a dog’s risk of developing benign tumors, including:

Breed Predispositions

Certain breeds are more prone to developing benign tumors. For example, Schnauzers are at an increased risk for develop sebaceous adenomas while Boxers and Boston Terriers are prone to mast cell tumors (Source).


Older dogs are more likely to develop benign tumors than younger dogs. Most tumors tend to develop in middle-aged to senior dogs over the age of 5.


Hormonal imbalances can trigger tumor growth in some cases. For example, estrogen can stimulate the growth of mammary tumors in female dogs that have not been spayed (Source).


Genetics and heredity play a role in some types of tumors. Dogs with certain genetic mutations may be predisposed to developing benign growths (Source).

Signs and Symptoms

There are various signs and symptoms that may indicate a benign tumor in a dog. Some of the most common include:

Visible or palpable lumps: One of the clearest signs of a benign tumor is the appearance of a lump on or under the skin. These lumps are typically round, firm, and movable. They are often benign fatty tumors called lipomas. Other benign lumps like sebaceous cysts may also form on the skin.

According to VCA Hospitals, vascular tumors like hemangiomas often appear as raised red lumps under the skin and can sometimes rupture and bleed.[1]

Changes to skin or fur: Benign skin tumors can cause changes to the skin surface or coat in dogs. The area around the tumor may become hairless, thickened, discolored or develop an ulcer. Tumors on the eyelid may cause swelling or bulge outward.

Discharge: Some benign tumors like sebaceous cysts can rupture and leak fluid. This discharge is often thick and foul smelling. There may also be bleeding from some tumors.

According to Merck Veterinary Manual, mast cell tumors can become ulcerated and ooze blood or serum.[2]

Bleeding: Spontaneous bleeding can occur with vascular tumors like hemangiomas. The blood vessels in the tumor are fragile and can burst. Internal tumors may bleed into the body cavity.

Signs of internal bleeding include weakness, lethargy, pale gums, distended abdomen and collapse.[1] External tumors can also bleed through broken skin.


Diagnosis of benign tumors in dogs will usually start with a thorough physical exam by the veterinarian. They will inspect and palpate the tumor, looking at its location, size, texture, and how it appears relative to the surrounding tissue. The vet may take samples of the tumor tissue to examine under a microscope, known as a biopsy. This allows the vet to analyze the tumor cells and identify them as benign. Imaging tests like x-rays, CT scans or ultrasounds can also be used to view the tumor and see if it has spread or impacted other areas of the body.

While some benign tumors like lipomas have a characteristic appearance allowing for diagnosis through physical exam alone, others like mast cell tumors require biopsy for definitive diagnosis. The vet will consider factors like the tumor’s rate of growth and characteristics when deciding the appropriate diagnostic steps. In cases where the vet strongly suspects a benign tumor through initial exam, they may forego biopsy due to the invasive nature of the procedure. However biopsy remains the gold standard for confirming benign tumors versus malignant ones. With a combination of physical exam, biopsy, and imaging, vets can accurately diagnose benign tumors in dogs.

Can Benign Tumors Rupture?

Yes, it is possible but rare for benign tumors to rupture in dogs. This occurs most often with hemangiomas, which are benign tumors arising from blood vessels. According to VCA Animal Hospitals, hemangiomas can rupture and cause internal bleeding, leading to symptoms like weakness, collapse, pale gums, distended abdomen, and chest bruising.

Some reasons a benign tumor may rupture include:

  • The tumor outgrows its blood supply, leading to necrosis and rupture
  • Trauma or injury to the area of the tumor
  • Ulceration of the tumor surface
  • Location of the tumor in an area vulnerable to motion or pressure

Signs that a benign tumor has ruptured may include:

  • Sudden collapse or weakness
  • Pale gums
  • Distended or painful abdomen
  • Bruising on the skin near the tumor site
  • Weakness or paralysis in the limbs if the tumor is near the spine
  • Labored breathing if blood accumulates in the chest

Rupture of a benign tumor is an emergency requiring prompt veterinary care. Owners should monitor benign tumors closely and contact a vet immediately at the first signs of rupture.


The main treatment for benign tumors in dogs is surgical removal. Surgery allows full removal of the tumor to prevent further growth. Depending on the type, size, and location of the tumor, surgery may be done using laser excision, cryosurgery (freezing), or traditional surgical excision.

Medications may be prescribed post-surgery to manage pain and inflammation. Antibiotics may also be given to prevent infection. For inoperable tumors, medications can help slow growth and relieve symptoms. Corticosteroids like prednisone may be prescribed. Other medications like chemotherapy drugs or nonsteroidal anti-inflammatory drugs (NSAIDs) may also be used.

At home care after surgery focuses on keeping the incision site clean and preventing your dog from licking or scratching it. An Elizabethan collar may be needed. Your vet will provide instructions on changing bandages, monitoring for signs of infection, and managing pain and medication. Gentle walks and restricting activity helps dogs heal post-surgery.

Recovery and Outlook

The recovery time and prognosis for a dog after surgery to remove a ruptured benign tumor depends on the location and extent of the tumor. Small benign tumors that are completely removed generally have an excellent long-term prognosis.

For splenic hemangioma rupture, studies show 85-90% of dogs have a good to excellent prognosis after splenectomy if the tumor was benign. One source states dogs with a ruptured splenic hemangioma that undergo splenectomy have a median survival time of about 2 years if no metastases are present.

Post-operative care often includes antibiotics, pain medication, rest, and a bland diet to allow healing. Activity is restricted for around 2 weeks. Follow up appointments and imaging tests are done to monitor for recurrence. With benign tumors that are fully resected, dogs can often return to normal activity levels and enjoy a good quality of life.

The prognosis is worse if the benign tumor has metastasized before rupture or if any cancerous cells remain after surgery. In these cases, chemotherapy may be recommended and life expectancy is more limited. But removing the ruptured main tumor still provides important palliative care. Consulting a veterinary oncologist can provide more accurate prognosis information.


While it’s not always possible to prevent benign tumors from developing in dogs, there are some steps owners can take to try to reduce the risks:

  • Get regular veterinary exams. Annual check-ups allow vets to thoroughly examine the dog and detect any abnormal growths in the early stages when they are small and easier to treat. Monitoring changes year-over-year can help identify developing tumors.
  • Carefully monitor any lumps or growths on your dog’s body. Keep an eye out for any new lumps appearing or existing ones changing size, shape, color, etc. and notify your vet promptly. Catching tumors early is key.
  • Keep your dog at a healthy weight. Obesity can increase inflammation and hormone imbalances, potentially contributing to tumor formation. Feeding your dog a nutritious diet and ensuring adequate exercise can help avoid excess weight gain.
  • Consider preventative medications. Non-steroidal anti-inflammatory drugs (NSAIDs) may help reduce tumor risk in some breeds prone to growths. Discuss options with your veterinarian.
  • Protect your dog from sun damage. Exposure to UV radiation can damage skin and increase cancer risks. Use dog-safe sunscreen and limit time in the sun during peak hours.

While not a guarantee, focusing on early detection and overall health is currently the best way to try to prevent benign tumors in dogs. Always discuss any concerns with your veterinarian.

When to See a Vet

Although most benign tumors in dogs are not life-threatening, there are some warning signs that indicate a visit to the veterinarian is warranted. Signs that a benign tumor may have ruptured or otherwise requires urgent vet attention include:

  • Signs of rupture – Open sores, bleeding, or oozing discharge from the tumor site can indicate a rupture.
  • Rapid growth – A tumor that suddenly grows much faster may be at risk of rupturing.
  • Discharge – Any oozing from the tumor, especially foul-smelling discharge, warrants an exam.
  • Bleeding – Any bleeding from the tumor is not normal and needs to be evaluated.
  • Pain – If a formerly benign tumor begins causing pain, it could indicate complications.

Even with benign tumors, it’s important to monitor for any changes and seek veterinary care if the dog shows signs of distress. Rapid changes or concerning symptoms associated with the tumor require an immediate trip to the vet to assess the situation and determine appropriate next steps for treatment.

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