Melissa Durfee asked: >What is the normal reaction to a vaccination? The "normal" reactions range from none at all to a life-threatening allergic reaction. The latter are rare but have been reported in ferrets receiving any of several vaccines. The rate of severe reactions varies (1) with each vaccine, (2) with the vaccination experience of the animal (you need to be previously exposed to a vaccine before you can react to it, so severe reactions never happen upon a first exposure), and (3) with the genetic or immunologic predisposition of each animal. It is very important to note that there can be normal reactions that are part of the body's immune response to the vaccine. I can't make a list of which reactions are normal and which indicate a severe allergic response because that varies with each vaccine. For Fervac-D, the vaccine consists of a so-called "modified live" virus, which has been adapted over many growth cycles in the lab to infect chick eggs and not ferrets. The vaccine actually "infects" the ferret when it is vaccinated but it has almost no chance of actually causing distemper in your ferret because the virus in the vaccine has been modified to grow in chicken cells, which belong to an entirely different taxonomic class of animal. Following a vaccination with a modified live distemper virus, any severe reactions seen within the first hour are likely to be allergic reactions and a vet should see the ferret at once. These reactions include convulsions, shock or torpor, bluish-purple blotches spreading under the skin, sudden anemia (look at the gums) combined with shock...I'm probably missing other symptoms, but you'll *know* something is wrong, and it will happen within an hour or so of the vaccination. Then there are the delayed reactions. Some people have interpreted these as severe allergic reactions but most of them are not at all. Anything resembling flulike symptoms that begin half-a-day or so after the injection probably means that your ferret's body is mounting an immune response to the vaccine. (That's why you vaccinate them to begin with.) These responses include, shivering, lethargy (*not* torpor, just usual tiredness or sleepiness); even vomiting may be part of the normal response if it follows the vaccination by several hours. If these flulike symptoms don't go away within a day, then call your vet, but otherwise, it means that your ferret's body is fearing up to battle the virus and whipping the immune system into a frenzy. It is worth noting that there is always a slim chance of so-called "breakthrough" infection with a live virus, such as some kids in the 1950s who actually caught polio from an injectable modified live polio vaccine. You make that decision on your own...take a *very* tiny risk of your ferret getting distemper from the vaccine, or fail to vaccinate and take a 100% risk of your ferret dying if it is ever exposed to distemper. You don't have to be a statistician to make that choice. Other vaccines don't always produce flu-like symptoms depending on how they're produced. Finally, returning to the lymphoma thread, I've spoken with United Vaccines and they *do* screen the chick eggs they use for freeloading microbes. I'm getting a copy of the procedures they use to screen for contaminants which I'll run by the virologists at the university. So, that puts vaccines low on the list of ways to transmit the purported lymphoma virus. The most likely route of transmission now appears to be ferret-to-ferret (called horizontal transmission by us infectious disease types) within households, possibly complicated by genetic susceptibility (one of the households of ferrets studied by Susan Erdman had more cancers in pandas and DEWs but not in other households, so it may vary by breeder or be a spurious association). So, I'd exhort those who have had multiple cases of lymphoma among their ferrets to try to think whether the ferrets who got cancer had anything in common compared with other ferrets who didn't get lymphoma. The knowledge to stop the spread of this virus may be out there. --Jeff Johnston ([log in to unmask]) [Posted in FML issue 1726]