I would like to say something about checking complete blood cell counts for the POSSIBLE presence of lymphoma in the ferret in response to Dr. Williams comment that it can't be used to diagnose lymphoma. In our practice, we recommend looking at complete blood cell counts on ferrets starting at one year of age and at least annually thereafter. (Under six months of age, ferrets can have a naturally occuring high lymphocyte count) We look for a variety of things, but in particular, we check for a high lymphocyte count. If the lymphocyte count is high (over 60% OR over 3500 absolute count) then we recheck it in 2-4 weeks, because, as Dr. Williams suggested, the count may be high due to other causes. The reason we have to look at one or the other parameter is because, in our practice, the total white blood cell count may not be over 3500 and then we look at percent. In cases where the total white blood cell count is very high, then we look at the absolute amount. At any rate if in 2-4 weeks the high lymphocyte count persists, then we suggest a lymph node removal (the popliteal along the back of the thigh, only a pea sized tissue) for positive confirmation of lymphoma. The sad fact is in our area that 80% of the cases that had the persistently elevated lymphocyte count turn out to be LYMPHOMA. We have two pathologists check all our samples so there is no question that it is pathology error, one being Dr. Susan Erdman who is doing most of the research on this disease at M.I.T. She is VERY picky about what she calls lyphoma or not. We diagnose it EVERY WEEK in our practice (our 4 man strictly exotic animal practice sees about 18% of all its patients as ferrets). I realize that there may be a regional difference in how much lymphoma is seen, but it is out there. The other 20% turn out to be hyperplastic, but the sad thing is that as we follow their complete blood cell counts over the next year or two, we have had at least 50% of those become positive for lymphoma at a later date when we check another lymph node. I would agree with Dr. Williams, that there are certainly other reasons that the lymph nodes can be overactive or "hyperplastic" and the chronic infection with Helicobacter is certainly high on the list. Therefore, I think, after screening ferrets this way for over 3 years, that the CBC is a very valuable tool to look for lymphoma, but NOT TO DIAGNOSE IT ALONE. It is about the only tool we have right now, as there is no test specifically for lymphoma. We find that the cases that respond to chemotherapy the best are those that are caught early with screening before they have serious clinical signs. Most of these ferrets that we are finding this way range in age from 8 months to 3 years of age (in older ferrets we usually see obvious clinical signs) with no clinical signs. Scary, but true. Just thought I would throw in my two cents worth. Susan Brown, D.V.M. [Posted in FML issue 0731]