Spleen Cancer in Dogs: Symptoms, Diagnosis, and Treatment

Subtle signs emerge before a crisis, so timely checkups are vital for your pet's comfort.

By Sneha Tete, Integrated MA, Certified Relationship Coach

Created on Sep 10, 2025

Subtle signs emerge before a crisis, so timely checkups are vital for your pet's comfort.

Spleen cancer, also known as splenic tumors, represents a major health threat in dogs. The spleen is an essential organ in your dog’s body, helping filter blood and support immune system functions. Tumors of the spleen can be benign or malignant, but malignant forms, such as hemangiosarcoma, are especially aggressive and can quickly threaten a dog’s life. Understanding the symptoms, diagnostic process, treatment options, and care strategies is vital for any dog owner facing this condition.

What is Spleen Cancer in Dogs?

Spleen cancer refers to the development of abnormal, uncontrolled cell growth within the spleen. Tumors in this location can be primary (originating in the spleen) or metastatic (spreading from elsewhere). The most common malignancy affecting the canine spleen is hemangiosarcoma, a cancer arising from the spleen’s blood vessel cells. Other tumor types include lymphoma and mast cell tumors, though they are less common.

The Role of the Spleen

The spleen performs several critical functions:

Filters and removes old or damaged blood cells from the circulation.
Helps produce and store certain types of white blood cells critical to immunity.
Acts as a blood reservoir, providing a backup supply in cases of sudden blood loss.

Types of Splenic Tumors in Dogs

The behavior, prognosis, and treatment options for spleen cancer depend largely on the tumor type.

Type	Description	Notes
Hemangiosarcoma	The most common splenic tumor in dogs. Originates from blood vessel cells. Highly aggressive with rapid metastasis.	Poor prognosis; surgery and chemo may increase survival up to 9 months in some cases.
Lymphoma	Cancer of lymphocytes, which can involve the spleen as part of widespread disease.	Usually part of multi-organ involvement; treatment and prognosis vary.
Mast Cell Tumor	Arises from mast cells; rare within the spleen but possible.	Treatment depends on extent and classification.
Benign Tumors or Nodules	Non-cancerous growths can occur, such as hematomas or nodular hyperplasia.	Benign but can rupture and cause internal bleeding.

Symptoms of Spleen Cancer in Dogs

Signs can be subtle in the early stages but may progress quickly as the disease advances, especially if the tumor ruptures and causes internal bleeding.

Abdominal swelling or distention
Lethargy and weakness
Loss of appetite
Weight loss
Pale gums (indicative of anemia)
Difficulty breathing (especially after bleeding episodes)
Collapsing or sudden fainting spells
Increased heart rate
Discomfort or sensitivity in the abdomen

If you notice any of these signs, especially acutely, seek immediate veterinary care. Ruptured spleen tumors can cause life-threatening hemorrhage.

Causes and Risk Factors

Breed predisposition: Large or deep-chested breeds, notably German Shepherds, Golden Retrievers, and Labrador Retrievers, are more commonly affected.
Age: Spleen tumors occur more frequently in middle-aged and senior dogs, though all ages can be at risk.
Genetics: Family history may increase susceptibility.
Exposure to carcinogens: Environmental risk factors (though not always clearly established).

Diagnosis of Spleen Cancer in Dogs

Timely and accurate diagnosis requires a combination of clinical assessment and diagnostic tools:

Physical exam: The veterinarian palpates the abdomen for swelling or masses.
Blood tests: Evaluate red and white blood cells, platelets, organ function, and signs of internal bleeding.
Imaging:
- Ultrasound: The most effective method to detect spleen masses, assess size, shape, and evidence of rupture.
- X-rays: To evaluate for masses, abdominal fluid, or spread to the lungs.
- CT scan/MRI: Occasionally used for in-depth analysis or surgical planning.
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Fine needle aspiration or biopsy: Extracts a tissue sample from the spleen mass for microscopic evaluation and definitive diagnosis.
Abdominal tap: May be performed if internal bleeding is suspected, retrieving abdominal fluid to assess for cancer cells.

Definitive diagnosis typically comes only after surgical removal and histopathologic assessment of the spleen.

Stages and Progression

The severity and prognosis of spleen cancer depend on several factors:

Tumor type: Malignant tumors (especially hemangiosarcoma) behave more aggressively than benign masses.
Spread (metastasis): Whether cancer has moved to other organs (commonly the liver, lungs, heart, or abdominal lining).
Rupture and bleeding: A ruptured tumor causes sudden symptoms and may require emergency intervention.

Treatment Options for Spleen Cancer

The treatment route depends on the cancer type, spread, and overall health of the dog. Main options include:

Surgical Removal (Splenectomy)

Primary treatment for many dogs with localized splenic masses, whether benign or malignant.
Emergency surgery is often required in cases of rupture and internal bleeding.
Recovery depends on the dog’s condition, presence of metastasis, and promptness of treatment.
Surgery alone offers limited survival benefit for splenic hemangiosarcoma: average survival is 2 weeks to 3 months.

Chemotherapy

Often recommended after surgery if the tumor is malignant, especially for hemangiosarcoma and lymphoma.
Median survival with surgery and chemotherapy for hemangiosarcoma may increase to 6â9 months. Fewer than 10% live past one year.
Chemotherapy may be used alone in some cases if surgery is not possible.

Palliative Care

For non-operable cases or tumors with extensive metastasis, the focus is on comfort.
Includes pain management, anti-nausea medications, and medications to control bleeding (such as Yunnan Baiyao).
May also include diet adjustments and fluid therapy to maintain quality of life.

Follow-up and Monitoring

Requires regular examinations, blood tests, imaging updates, and careful observation for recurrence or complications.

Prognosis and Life Expectancy

Survival and prognosis depend largely on the tumor type and how advanced the cancer is at the time of diagnosis:

Benign tumors: Dogs usually recover well post-surgery and can live normal lifespans, provided no serious complications have occurred (such as massive internal bleeding).
Splenic hemangiosarcoma: Prognosis remains poor, with surgery plus chemotherapy yielding a median survival of 6â9 months. Less than 10% survive past a year.
Lymphoma involving the spleen: Prognosis can be guarded; it depends on systemic involvement and response to therapy.
Mast cell tumors: Variesâearly detection and intervention may improve outcome.

Caring for a Dog with Spleen Cancer

Monitoring and Regular Veterinary Checks

Schedule regular vet visits, especially if your dog has a known splenic mass or is undergoing treatment.
Monitor at home for sudden behavior changes, collapsing, pale gums, abdominal swelling, or respiratory distress.
Emergency action is necessary if symptoms of internal bleeding occur.

Pain Management

Pain control is essential, especially in advanced or inoperable cases. Discuss medications and dosing schedules with your vet.

Nutrition and Hydration

Offer a balanced, palatable diet. Sometimes, tempting foods, treats, or veterinarian-approved supplements are needed for dogs with reduced appetite.
Ensure access to clean, fresh water at all times.

Supporting Quality of Life

Keep your pet’s environment calm, safe, and comfortable.
Provide gentle exercise if appropriate.
Follow the veterinarianâs advice on activity restrictions and wound care following surgery.

When to Consider Euthanasia

Deciding when to say goodbye is deeply personal and depends on the dog’s quality of life, degree of pain, ability to eat and move comfortably, and the progression of cancer. Signs indicating it may be time to consider euthanasia include:

Unmanageable pain or distress despite medication
Persistent anorexia and rapid weight loss
Repeat collapse events or evidence of ongoing bleeding
Lack of response to treatment or severe spread to other organs

Consult your veterinarian for guidance and compassionate support to make this difficult decision. Focus always on your petâs comfort and dignity.

Frequently Asked Questions (FAQs)

Can spleen cancer in dogs be prevented?

There are no proven methods to prevent spleen cancer in dogs, especially since most cases occur without obvious environmental triggers. Routine veterinary exams and prompt attention to unusual symptoms may help in early identification and management.

Should I pursue surgery if my dog is diagnosed with a splenic tumor?

Surgical removal (splenectomy) is often recommended for splenic massesâeven benign tumors can rupture without warning. The decision depends on factors such as your dogâs age, general health, cancer type, and whether spread has already occurred. Your veterinarian will help you weigh the risks and benefits for your dogâs individual case.

How long can a dog live with spleen cancer?

Survival times vary greatly and depend largely on tumor type. Benign tumors may allow for full recovery; hemangiosarcoma carries a poor prognosis, with average survival times of 2 weeks to 3 months (surgery only), possibly up to 9 months with chemotherapy.

Is hemangiosarcoma hereditary in dogs?

There is evidence that some breeds have a genetic predisposition to hemangiosarcoma, but precise inheritance patterns are still being studied.

What can I do to support my dog during treatment?

Be diligent with all medications and follow-up appointments.
Monitor for and promptly report any changes in condition to your veterinarian.
Provide emotional support, a peaceful environment, and spend quality time with your companion.

Key Takeaways for Pet Owners

Spleen cancer in dogs is a serious but manageable diagnosis when caught early.
Monitor your pet for symptoms of abdominal swelling, weakness, or sudden collapse, and seek veterinary care promptly if these arise.
Surgery is often the primary treatment and can be life-saving even for benign masses.
Prognosis is poor for malignant cancers like hemangiosarcoma, though surgery and chemotherapy can extend survival and improve quality of life.
Compassionate care, pain management, and attention to quality of life are fundamental throughout your dogâs illness.

References

Author

Sneha TeteBeauty & Lifestyle Writer

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to thebridalbox, crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

Read full bio of Sneha Tete