The dog spleen is an important organ located in the abdomen. Spleens are so important that almost every species of vertebrate animal has one and some species have multiples.

Depending on the species, the spleen may be used for blood storage and defense as part of the immune system. The spleen in some species like rabbits cannot expand to store blood but has defensive activities. Other species like the dog and cat have spleens that store blood and participate in immune defense.

The spleen has an extensive network of blood vessels and has the capacity to contain a large volume of blood. In addition, the dog spleen has a significant amount of smooth muscle in the capsule area. This allows, when signaled, for contraction of the spleen and pushing blood into the main bloodstream. It has been estimated that the dog can store one-third of its blood in the spleen at rest.

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Another important function of the spleen is to filter out and remove old, damaged, or abnormal red blood cells from circulation. As part of the body defense, while blood is passing through the spleen, immune cells like lymphocytes and macrophages are able to monitor the blood and react to infection and foreign antigens.

Like all organs in the body, the spleen is subject to a number of health problems. With its location in the abdomen near the stomach, and its extensive blood supply, the spleen can be injured by blunt trauma like can happen when hit by a car. With severe enough trauma, the spleen can rupture and leak blood into the abdomen. With enough blood leakage the dog can go into shock and collapse. The ability of the body to control the leakage (hemorrhage) depends on many different issues. These situations can be an emergency requiring urgent care.

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Beyond potential issues from trauma, the spleen is also affected by tumors (nodules, swellings, growths) that can range from benign to highly malignant. These growths include hemangioma (benign), blood clots caused by another concurrent disease process like cancer (i.e. lymphoma) or immune-mediated disease (i.e. immune-mediated hemolytic anemia), or hemangiosarcoma (malignant).

Clearly identifying the cause of the tumor is important even though some causes are considered benign because they can all result in possible rupture and hemorrhage. The body can usually handle small amounts of hemorrhage but frequent small amounts or sudden large amounts can lead to problems like weakness and collapse. It can be difficult to determine that there is a problem with the spleen because of its location in the abdomen and the body’s ability to adapt and deal with problems. Sometimes the spleen tumor can be large enough that it can be felt by your veterinarian during an examination. Other times it can only be found with a radiograph or ultrasound.

A dog having an episode of life-threatening bleeding may appear to be suddenly weak, have pale-colored gums, and be cold to the touch. These are indications that the dog is experiencing shock and should be seen immediately by a veterinarian so that appropriate care can be initiated. In some situations the bleeding can stop on its own and the dog can appear back to normal hours or days later. The hemorrhage can lead to anemia because the blood is pooled in the abdomen and not flowing in the blood vessels. Yunnan Biayao is a Chinese herb combination that has shown benefits for helping to reduce bleeding and can be an important part of managing splenic bleeding episodes.

When masses are found affecting the spleen, evaluation for concurrent disease is important so those contributors can be addressed specifically. However, it may be clear after examination that the spleen should be removed to prevent rupture or to manage ongoing bleeding.

Once the spleen is removed, the tumor should be evaluated by a pathologist to determine what is happening at the microscopic level. This is important for determining what steps to take for further therapy. For example, often the benign causes can be managed by removing the spleen while the malignant causes like hemangiosarcoma should receive follow-up care like chemotherapy or mushroom extracts which appeared to be an effect alternative in a university based study for this serious problem. Even though the spleen is an important organ, dogs can do well without a spleen.

If you have concerns about your pet companion’s spleen contact your veterinarian.

Ron Carsten, DVM, PhD, CVA, CCRT was one of the first veterinarians in Colorado to use the integrative approach, has lectured widely to veterinarians, and has been a pioneer in the therapeutic use of food concentrates to manage clinical problems. He is also the founder of Colorado Animal Rescue (CARE). In addition to his Doctor of Veterinary Medicine, he holds a PhD in Cell and Molecular Biology and is a Certified Veterinary Acupuncturist and Certified Canine Rehabilitation Therapist. He practices integrative veterinary medicine in Glenwood Springs. Dr. Carsten is the 2022 Colorado Veterinary Medical Association Distinguished Service Award recipient.