To Reno, who had his spleen removed: Methinks your vet needs to talk with someone who is more familiar with ferrets and their diseases. Enlarged spleens are very common in ferrets, especially in older ones. Having seen this problem for years, we still do not have any idea which casues most of the cases. In my experience, less than ten percent have a definite etiology - usually lymphosarcoma, but you can see several other tumors arise in the spleen. The remaining 90% show a combination of congestion (basically filling with blood), and extramedullary hematopoiesis (the forming of new red and white-blood cells in an area other than the bone marrow). We still don't know why ferrets do this, but the prevailing, and most logical opinion, is due to a chronic infection, such as Helicobacter infection of the stomach, which is VERY common in ferrets. Chronic, low-grade infections require increased numbers of white blood cells to fight them, so ferrets make more, generally in the spleen. When the spleen gets very big, it tends to displace other organs, and the ferrets usually become lethargic and don't feel up to snuff. Plus a large spleen has an increased chance of rupture as a result of minor trauma. So they are commonly removed, and the animals go on and do just fine. Blood cancer (most likely lymphosarcoma) occurs in less than ten percent of cases; there is a ninety percent chance that your ferret doesn't have it, and should be just fine. But you never know unless your vet has the spleen BIOPSIED!!! Yes, having it looked at by a pathologist will markedly change the course of treatment - either nothing, in the case of congestion and EMH, or chemotherapy in the case of lymphosarcoma. The vast majority of ferrets with their spleens removed do just fine - a guarded prognosis is probably a bit severe. I have never seen medical complications in a ferret that does not have a spleen, as long as the surgery is done properly. Check with your vet and see if you may be able to take Reno home early - he may do better at home. He won't get better any faster in a cage at your vet's. And get that spleen looked at!!! (If your vet wants to send it to me, I don't charge anything. He/she can use the address and phone listed below.) Good luck with Reno. Bruce Williams, DVM Department of Veterinary Pathology [log in to unmask] Armed Forces Institute of Pathology (202) 576-2453/2454 Washington, D.C. 20306-6000 [Posted in FML issue 0802]