Anatomy and Function of Your Dog’s Spleen

Anatomy of the Dog’s Spleen

The spleen is an abdominal organ located on the left side of the dog’s abdomen, situated closely to the stomach and the liver. It is often described as slipper-shaped because of the broad, rounded ends with a narrow middle portion.

The spleen’s consistency is very similar to that of the liver and has a relatively fragile structural integrity. It can easily rupture or be damaged from external blunt forces. The spleen is a highly vascularized organ, containing numerous small, winding blood vessels inside. Any damage to the spleen, even if very small, can lead to significant internal bleeding.

The blood supply of the spleen comes from numerous major blood vessels. The splenic artery and vein, responsible for carrying blood to and from the organ, branch off major blood vessels that are responsible for the blood supply of most gastrointestinal organs. There are certain health conditions in dogs that may require removal of the spleen through a surgical procedure called splenectomy, and the most common complication from this procedure is hemorrhage from any of the blood vessels connected to the spleen.

Functions of the Dog’s Spleen

The spleen has many functions inside the dog’s body. These functions help maintain the animal’s optimal health and immunity, playing an important role in fighting off certain infections and addressing other problems related to the dog’s blood supply and circulation. Despite this, a dog can actually live without its spleen, and in certain situations, removal of the organ can help improve the survivability of some conditions.

1. The Body’s Natural Blood Bank

As mentioned, the spleen contains numerous small blood vessels inside. The extent to which these vessels wind around inside the spleen causes the flow of blood and red blood cells inside the organ to slow down significantly. This means that at any given time, the spleen contains a very high amount of red blood cells. This makes the spleen a natural blood bank for the animal, which can be helpful in cases of acute hemorrhage.

The spleen also has smooth muscles in its capsule which provides the ability to contract. When the dog suffers from acute blood loss, the spleen contracts to release the blood stored inside the organ. This provides an immediate fresh supply of blood to the animal in response to blood loss.

2. Recycling Red Blood Cells

Like all cells in a dog’s body, a red blood cell has a lifespan and eventually dies on its own after around 110-120 days. As it becomes older, it also becomes more fragile compared to its younger counterparts. The rate at which red blood cells die is almost the same as the rate of production of new red blood cells to maintain homeostasis in the dog’s circulatory system.

Older, more fragile red blood cells also travel through the spleen regularly, but because of the winding course of the blood vessels inside, they become damaged and eventually rupture. This process allows the spleen to remove older red blood cells and signals the bone marrow to produce new ones, which are more efficient in delivering oxygen and nutrients.

The ruptured old red blood cells release hemoglobin which the spleen captures to be used for the production of new ones. This function is the reason why the spleen is often called the graveyard of red blood cells.

3. Control of Red Blood Cell Infections

The spleen also helps control the spread of blood parasite infection in dogs infected with blood parasites such as Babesia sp. These blood parasites attach to the surface of the red blood cells and cause damage, leading to severe anemia and possible death if uncontrolled or not treated properly.

As mentioned above, all red blood cells circulating throughout the dog’s body will have to go through the spleen, even infected ones. Because of the winding vessels inside the spleen, the parasite in infected red blood cells traveling inside the organ is removed by the organ through a process called “pitting”. Through this process, the spleen eats off specific sections of the red blood cells where the parasite is attached.

The immune system marks these areas in the red blood cells so that when it goes inside the spleen, the organ knows exactly which sections it should “pit” or eat off. In some cases, the entire red blood cell is destroyed if there is a high number of blood parasites attached to it.

4. Component of the Lymphatic System

The spleen has two distinct sections called the red pulp and the white pulp. The functions described above all occur in the red pulp of the spleen. The white pulp, on the other hand, is connected to the dog’s lymphatic system and acts as a lymph node for the animal. It contains a high concentration of lymphocytes, which are released when the dog is fighting off an infection.

Read more:

The Importance of Kidney Health and Function in Dogs and Cats

Your Pet’s Heart: A Guide to Understanding Heart Health in Dogs and Cats

The Dog Digestive System: Anatomy and Functions

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