The spleen is an organ in the abdomen of dogs and cats.  It is a storage spot for extra red blood cells and also some other functions, but in general, it is not an organ that is needed to survive.

We see splenic problems more commonly in dogs rather than cats. Dogs will get masses growing on their spleens and they can be of different types and sizes. Splenic masses can grow large enough or become fragile enough that it ruptures and bleeds into the abdomen (hemoabdomen), which is typically a surgical emergency.

If you take a look at a large population of dogs, 50% of the masses on spleens are cancer and 50% are hematomas, basically bruises.  Regardless of the type of mass that it happens to be, they all have a high chance of rupturing, so surgery is indicated to remove the spleen, even if the mass is found incidentally. Then we submit the spleen to a pathologist to find out what type of mass it is and then talk about further treatment options, if there are any. The other factor regarding splenic masses is it’s nearly impossible to diagnose the type of mass without going to surgery. The other diagnostic tests that we have, like needle aspirates, are usually non-diagnostic, due to all the blood that gets mixed in with the sample.

Dogs that come in with bleeding splenic masses are taken to surgery as soon as they are stable enough to undergo the anesthesia, which is usually within a couple hours or less, in many cases.