Skip to Content

Dog Spleen Tumors – Top Guide

Dog spleen tumors (splenic masses) often go unnoticed because of their hidden location and vague symptoms.  As with any tumor they are either benign (non-cancerous) or malignant (cancerous).

You might feel as if your dog has something wrong, but you can’t quite put your finger on what it is. In fact, it’s not unusual for people to miss the early signs and symptoms. 

To Understand Dog Spleen Tumors, You Need to Understand the Spleen

The spleen is located next to your dog’s stomach and is one of the body’s vascular organs.  It’s “vascular” because it regulates blood cells and recycles blood protein and iron. In addition, the spleen contains cells that recognize harmful microorganisms in the body.

The spleen has two types of tissue:

Red Pulp Tissue

Activity in red pulp tissue helps filter blood and recycle the proteins and iron from blood cells. The red pulp connective tissue makes up about 79% of the spleen.  This part of the spleen contains many different blood cells including:

  • Platelet (thrombocytes): These cells promote blood clotting.
  • Red Blood Cells: These cells are responsible for delivering oxygen to body tissues.

White Pulp Tissue

White pulp tissue contains cells that create an immune response when infection, viruses, or bacteria threaten the body. They constantly protect the body against illness.  White blood cells are created from bone marrow.

Types of White Blood Cells Include:

-Monocytes (help to break down bacteria)

-Lymphocytes (create antibodies to protect against bacteria, etc.)

-Neutrophils (kill bacteria and fungi)

-Basophils (these are the alarm-sounders when infectious agents appear)

-Eosinophils (kill parasites, destroy cancer cells, and help with allergic reactions)

Is There a Cure for Dog Spleen Tumors?

There is no cure for dog spleen tumors. Science hasn’t been able to identify the triggers that cause body systems to malfunction and allow cancer to grow. Early diagnosis offers the best outcome.

Surgical removal is the only way to determine whether the tumor is malignant (cancerous) or not.

Symptoms of Dog Spleen Tumors

Dog spleen tumors are often masked by vague symptoms.  Sometimes it takes a full splenic rupture to reach a diagnosis.

Vague symptoms could include weakness, sudden weight loss, extreme fatigue.

Two Characterizations of Spleen Tumors:

Tumors of the spleen are considered either non-lymphoid or lymphoid.  

Lymphoid Tumor

Lymphoid tumors originate in the lymphatic tissue within the dog’s spleen. They can occur in other areas as well including the lymph nodes or in the bone marrow.

Lymphoid (cancer of the lymphocytes)

Cancers of the lymphocytes (white blood cells that reside in the white pulp of the spleen) are common in dog spleen tumors. Other cancers of the lymphocytes include: mast cell tumors and leukemia.

Tumors of the spleen are hidden from view most of the time.  Regular checkups with a licensed veterinarian may help identify them in the early stages.

Non-lymphoid (cancer of the blood vessels)

This category of dog spleen tumors include non-cancerous hemangioma (benign) and cancerous hemangiosarcoma (malignant). 

Hemangiosarcoma (non-lymphoid)

Hemangiosarcomas are malignant cancers that develop in blood vessel lining. It can be found in any organ; however, with dogs they tend to appear in the spleen. 

The Immediate Danger of Hemangiosarcoma

Unfortunately, cancer on the spleen isn’t typically noticed until it becomes enlarged, and even then only a medical professional knows what to feel for.

Hemangiosarcomas are tumors that begin in the lining of blood vessels. The tumor presents as a big mass lodged onto a vascular organ (like the spleen).

Since it’s vascular in nature (relates to the blood vessels) a lot of blood passes through and accumulates.  The bigger it grows, the greater the chance of a rupture causing a dangerous internal bleed. Most times this is fatal.

If the veterinarian does suspect there is a tumor on the spleen, the spleen will need to be removed. If test results come back benign, you have hope. If the test results show cancer after the spleen is removed, there’s a chance the cancer has already spread to other organs.

READ: Canine Hemangiosarcoma Stages in Dogs

Medical Treatment for Dogs with Splenic Tumors

Chemotherapy can be offered after the spleen is removed to catch any remaining cancer cells in the body. It’s not a cure, but it can extend your dog’s life by weeks or months.

It should be noted that there are cases where dogs have gone on to live many years after surviving a splenic tumor.

Post Surgical Vaccinations

As medical science evolves, hope for canine cancer treatment grows.

In Farmington, Connecticut, veterinarians and immunologists are working on harnessing an animal’s own immune system to fight cancer. This is achieved through a personalized vaccine.

For more information, visit American Veterinarian.

This post is not a substitute for regular veterinarian care. Your dog’s veterinarian should always be your first point of contact for any health-related concerns, diagnoses, and treatments.

Thank you so much for taking the time to read my post. Stick around, because there are plenty useful articles here. For example, discover 5 Clinical Signs of Fatty Tumors in Dogs OR 11 Potent Treatment Options for Lick Granulomas.

if you enjoyed this post and learned something new, please take a second to share!


Merck Vet Manual

Thank you for reading this post!

I want to take a moment to thank you for reading this post. I hope you found it useful and informative. If so, could you take a second to spread doggy love through social media?

You'll find the buttons at the top of this post and at the bottom of the post. might have noticed a little heart at the bottom left of your screen? Give it a click if you want to bookmark this page for future reference.