Jodie, an enlarged spleen may be caused by a long term infection or reaction These may be sub-clinical, ie there is no outward sign of anything amiss, such as raised temperature, or redness. The first thing I always think of is *teeth*. Sometimes if you (or a vet) simply lift a ferret's lip to check the back teeth, you will see white teeth and pink gums. This does not mean that there are no dental problems. A more thorough investigation would be needed, perhaps under sedation, to see if the teeth and surrounding bone are compromised in any way. The second thing I think of these days is IBD. It was only recently that a person mentioned that, as a vegetarian, she ate lots of bread. She suffered what was first diagnosed as IBD, and then later, as a glutin intolerence directly caused by overindulging in the "staff of life". It makes me wonder if, sometimes, the grain in kibble causes the same thing in ferrets. My vets consider it very plausible, but do not see it often enough to be able to look into it further. It would be great if US vets who see many such cases, would suggest a total glutin-free diet to see if there is any improvement or cure. I think your vet may be right. Cheers, Shirley [Posted in FML 5407]