A dog’s spleen is an organ located in the abdomen near the stomach. This dark red, elongated organ performs functions related to blood and the immune system. It filters the blood, removing old or damaged red blood cells and foreign particles like bacteria. The spleen also serves as a reservoir for red blood cells and platelets, components involved in blood clotting.
The spleen contributes to immune activities by housing specialized cells that identify unwanted bacteria or viruses. Finding a mass or abnormality in the spleen is a common reason for an ultrasound examination.
The Ultrasound Procedure
An abdominal ultrasound for your dog is a non-invasive, painless procedure. Before the examination, the hair on your dog’s abdomen is clipped for proper contact with the ultrasound probe. A water-based gel is applied to the clipped skin, transmitting sound waves from the probe into the body. Your dog lies comfortably on their side during the examination.
A veterinarian or specialist uses a handheld transducer probe, moving it across the abdomen. This probe emits high-frequency sound waves that bounce off internal organs, creating real-time images on a screen. Most dogs tolerate the procedure without sedation. For anxious dogs, a mild sedative might be considered to ensure they remain still and comfortable.
Interpreting Ultrasound Findings
During a dog spleen ultrasound, the veterinarian carefully evaluates several aspects of the organ’s appearance. They assess the spleen’s overall size, its specific shape, and its echogenicity, which refers to how brightly the tissue appears on the ultrasound screen. The echotexture, or the internal pattern and uniformity of the spleen’s tissue, is also closely examined for any irregularities. These observations help identify changes within the splenic parenchyma.
The ultrasound can reveal various abnormalities, such as a distinct, localized mass, multiple smaller nodules scattered throughout the organ, or a diffuse enlargement of the entire spleen. The presence of free fluid in the abdomen, known as hemoabdomen, is another significant finding that can indicate a ruptured splenic mass and internal bleeding. While an ultrasound can effectively locate and characterize a splenic mass, it cannot definitively determine whether the mass is benign (non-cancerous) or malignant (cancerous). The visual characteristics of benign lesions, such as hematomas, can sometimes appear similar to malignant tumors like hemangiosarcomas on ultrasound.
Common Types of Spleen Tumors
Once an ultrasound identifies a splenic mass, understanding the potential types of growths helps manage expectations about your dog’s condition. Splenic masses in dogs can be broadly categorized as either benign or malignant. Benign growths are non-cancerous and include conditions such as hematomas, which are collections of clotted blood, and nodular hyperplasia, an overgrowth of normal splenic tissue. Hemangiomas, which are benign tumors of blood vessels, also occur in the spleen.
Malignant, or cancerous, splenic tumors are a concern. Hemangiosarcoma is the most frequently diagnosed malignant splenic tumor in dogs, often affecting older, large breeds like German Shepherds, Golden Retrievers, and Labrador Retrievers. Other less common malignant tumors can include lymphoma, mast cell tumors, and histiocytic sarcoma.
Studies indicate splenic masses have roughly a 50% chance of being benign or malignant. If no internal bleeding (hemoabdomen) is present, the likelihood of a mass being benign increases to 63.1% to 70.5%. Conversely, if hemoabdomen is detected, the chance of the mass being benign drops to a range of 21.7% to 37.5%.
Next Steps After Diagnosis
After a splenic mass is identified, surgical removal of the spleen, a splenectomy, is commonly recommended. This serves a dual purpose. First, it removes the mass, eliminating the risk of rupture and life-threatening internal bleeding. Second, it is the only way to obtain a definitive diagnosis.
Once the spleen and any tumors are removed, they are sent for histopathology. This involves a microscopic examination of the tissue by a veterinary pathologist. Histopathology conclusively determines if the mass is benign or malignant, providing specific information about the tumor type and guiding future treatments. Dogs generally adapt well to life without a spleen, as other organs are able to take over its functions.