Final answer:
During abdominal palpation in a healthy dog, the spleen is the organ most likely to be palpable because of its size, location, and role as a blood filter.
Step-by-step explanation:
When performing abdominal palpation on a healthy dog, the organ that would most likely be palpable is the spleen. The spleen is a secondary lymphoid organ attached to the lateral border of the stomach by the gastrosplenic ligament. It is approximately 12 cm long and is located in the upper left quadrant of the abdomen near the stomach and left kidney. Due to its extensive vascularization and the presence of macrophages and dendritic cells that remove unwanted materials from the blood, it is sometimes palpable during a physical examination.