What does the dog’s spleen do?

The spleen is a bodily organ that sits just below the stomach, and helps the body to do several important things. However, spleen removal surgery may be necessary for dogs for certain reasons, such as if they have cancerous tumours or other problems of the spleen, and dogs that have their spleen removed in whole or in part generally live out the rest of their life perfectly fine and none the poorer for its loss! Some breeds of dog are also more apt to have spleen problems than others, such as the golden retriever.

The fact that dogs can live without a spleen is the source of some confusion for dog owners, who fairly assume that the spleen is ergo an unnecessary or non-functional organ as a result, much as many people view their appendix or adenoids, which are a couple of human body parts that can be removed with little to no future problems!

In this article, we will look at what the spleen does actually do for the dog when it is healthy, and explain the importance of these functions; and also, look at how come dogs can still live perfectly healthy lives after a spleen removal, or splenectomy. Read on to learn more!

What does the spleen do?

Firstly, the spleen serves as a type of backup storage for red blood cells, and it can also alter the construction of red blood cells and perform several other functions too.

When blood is pumped around the body by the heart, it is circulated through the spleen itself, which is rich in very narrow yet long blood vessels, compacted into circuits of bends and turns that the red blood cells themselves have to navigate to pass through the organ.

This means that at any given time, the spleen is rich in red blood cells, so that if the dog is at risk of becoming anaemic or suffers an injury that results in blood loss, the muscles of the spleen go to work, pumping its stored red blood cells out to reperfuse the body and assist with recovery.

Secondly, the spleen is responsible for removing and absorbing older red blood cells that are approaching the end of their lifecycle in the body. These older red blood cells break apart in the spleen, and as they break or rupture, they release iron, which the spleen then absorbs and recirculates to provide this essential element to the entire body.

The spleen also serves an important function as part of the immune system, by removing blood cell parasites and other hazards such as potential disease vectors from the blood. This occurs when the spleen acts on the red blood cells passing though it in a process called pitting, which means that the contractions of the spleen break off sections of certain red blood cells that the immune system has targeted as a hazard, removing the hazard from the cell itself before the cell is passed back out into general bodily circulation.

This helps to reduce the number of whole red blood cells that are destroyed by disease or infection, although the spleen can also remove whole red blood cells too, if necessary.

Ergo, the spleen performs a vital function for the immune system in preventing illness and disease.

As well as the functions that the spleen can perform for the body’s red blood cells, it also has implications for the lymphatic system too, which is another facet of the immune system that produces antibodies to attack infections and disease. This allows the spleen to function as a back-up system for the lymph nodes, by stimulating lymphocytes into action where necessary if this has not already been performed in the lymph nodes themselves.

How come dogs can live without a spleen?

While all of the above functions performed by the spleen are important as well as interesting, they also all serve as backups or supporting functions for activities that are either also performed by other bodily areas, or that are only required in an emergency.

For instance, the spleen will only need to release its stored red blood cells if the dog becomes anaemic or suffers a significant blood loss, problems that most dogs never face.

Iron is taken up and stored in other bodily organs too such as the liver, and so, this can still occur without a spleen.

In terms of the immune system, the spleen serves as an additional line of defence, secondary organ or backup, so once more, assuming that the rest of the dog’s immune system is performing as it should, the work performed by the spleen is secondary or supportive to this.

Finally, the lymph nodes themselves are again, usually able to function alone to produce and circulate lymphocytes, which means that the spleen’s functions in this area are valuable, but not usually essential for survival.

Whilst removal of the spleen should not be undertaken unnecessarily or without good reason, and if your dog is having a problem with their spleen, your vet will likely look at alternative methods of treating it before considering removal, dogs can usually live without their spleen at all, if something that warrants its removal occurs.

Splenic tumours are one of the more common types of cancer in dogs as they get older, which sometimes necessitates the removal of the whole spleen, and this, along with various other things, may all lead to the need for a splenectomy, or spleen removal.