I don't know if anyone else has any ferrets, so I am electing my Tino as the first (and only ?) ferret of the month. 
I've never owned a ferret, but I've seen too many to count as patients. They are really cool animals, the problem I have with them is the odor. It just turns my stomach. I can stand them at work, but not at home. I tried petsitting for a few ferrets when I was doing my residency and had to quit after that. I'd see them at work, then go back to my apartment and there'd be the ferret smell all over... I know its sounds bad, but I just couldn't stand it.
Tino is 9 years old, and is a cinnamon, though he has lost some of his fur from Adrenal Disease. Tino has had a melatonin implant inserted for the Adrenal instead of having surgery, because of his advanced age. He has also been diagnosed with Lymphoma, which has not been confirmed via biopsy, again because of his age. It is pretty much a given that he does have Lymphoma because of his enlarged lymph nodes. He was diagnosed at the end of April, and his lymph nodes seem to be enlarging very slowly. I am hoping that means it is affecting his internal organs slowly too, but since he won't be having surgery I do not know what is going on inside him.
Tino definately has that "OLD FERRET" grizzled look...
I think thats one thing that makes them cute---when they hit 7 or so and start to look like that.
You can generally readily diagnose lymphoma from fine needle aspirates of the lymphnodes, especially in slower growing cancers like Tinos seems to be. Obviously biopsy is the gold standard of confirming the disease. And honestly, in a ferret as old as Tino is, you are probably right just assuming it like you have. Remember, lymphoma in ferrets generally occurs as two forms. Its "visceral" meaning it affects the internal organs---these are the ferrets with GI lymphoma that have absolutely no clinical signs at all until suddenly one day thier intestine does something obtuse like they get a GI obstruction/stasis or the intestine just ruptures. Those are the most frustrating cases because they really don't have a good prognosis, diagnosis is often post mortem, and they may have no clinical signs at all until its too late.
The other form is "pheripheral" or affecting the lymph notes. This may be external lymph nodes like the ones you can feel under the foreleg or on the neck or it can be internal like those around the heart or intestine. These tend to be a bit more forgiving with their degree of warning before a bad outcome occurs. You can sometimes monitor the growth of the lymphnodes for months.
As a final note, one thing I've learned about Ferret lymphoma is it does what it wants too---its a very frustrating disease becuase just when you think you've understood the pathogenesis of the cancer, you will have a new case that does something completely off the walls. I've literally seen tumors in ferrets shrink to the point of disappearing when attempts to use chemotherapy were used to manage them only to have the ferret come out of remission a short time later with a seemingly new form so aggressive it responds to nothing chemotherapeutic wise. I honestly think with many cases its a better idea to just put the ferret on prednisone if the masses are very large to try to shrink them a bit and then let the ferret live out its natural life vs chemotherapy, radiation, surgeries and what not.
Tino eats the ground and partially cooked chicken gravy I make him, with fish oil added to it. He has a very good appetite and for 9 years old he is as active as I would expect him to be.
Tino lost his long term buddy Simon, on 4-12-07. Simon was also 9 years old. I expect Tino will be joining Simon sometime this year and my goal is to keep him around as long as he is comfortable.
He may surprise you
Is he still wanting to play and "ferret" around? That seems to be one of the keys with old ferrets. If they want to play, they live--they may have terrible disease that no dog or cat could live with, but the ferret will still live if it wants to play. If they don't, their prognosis is much worse.
