Spenalomegaly in ferrets is usually NOT malignant. In this it is like adrenal growths. Surgery to remove the spleen is typically without negative effects (also similar to adrenal growths) and the ferrets usually improve greatly after (a third similarity to adrenal growths). Imagine if you were carrying around a 40# spleen. Now imagine how much better you would feel without it. Ferrets don't tend to have negative consequences of such surgery. When a person is leery of trying surgery straight out, it sometimes can pay to try 4 or more weeks of Biaxin and Amoxi since most enlarged spleens in ferrets are from slowly smoldering infections and this combo hits several including helicobacter which is very common. That depends on how great the risk of rupture is. Your vet will gently pat/massage/move the spleen during surgery before removal to up the blood levels in the body first. If the margins are not smooth that increases the chances of it not being a benign problem, but benign spenalomegaly in older ferrets is very common. Meltie had 3 and 1/2 mostly excellent years in her after removal of a benign spleen and a malignant adrenal at age 5 years. [P.S.] Be SURE to have the spleen sent out for pathology and that the proper procedures (such as no freezing which bursts cells and ruins samples) are used so that the pathologist can check it carefully. [Posted in FML issue 3925]