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    distemper shots requirements
    wahart posted:
    My kitten Neko recieved his first distemper shot from the breeder at 10 weeks. The breeder said it is ok to wait 40 days for the 1st booster. Is this OK or should we go to our Vet sooner
    srstephanie responded:
    Hi wahart,

    I'm glad you asked. Waiting 40 days could put your kitten at risk of disease.

    The reason for a series of kitten vaccinations is that when kittens nurse in the first 18-24 hours after birth, they receive a special type of milk from the mother called colostrum. The colostrum is rich in antibodies. In the first about 24 hours, the kitten's intestines are porous enough to allow the maternal antibodies to pass directly into the blood stream and they are responsible for protecting the kitten from disease. After the first 24 hours, there is "gut closure" and no more antibodies are able to pass from the intestines into the blood stream.

    Those maternally derived antibodies (MDA) will interfere with the vaccines so that there is NO response to vaccines by the kitten. The MDA gradually decrease and there is a period of time (could last 6 or more weeks) in which the MDA is too low to protect the kitten from disease, but still high enough to interfere with vaccines. That is known as the Window of Susceptibility in immunology. Every kitten passes through it, so you have to know that even with vaccination there is a period of time when the kitten is not protected either by maternal antibodies or by response to vaccinations.

    So, the kitten series is given solely so that the vaccine can be there as soon as possible after the MDA drop low enough not to interfere.

    Studies have shown that there can be MDA interference out to 14-15 weeks of age. But it depends on what the mother's antibody level was at the time of birth and how much colostrum the kitten consumed in those critical first 18-24 hours. Many kittens may no longer have any MDA interference by 10-12 weeks ... in which case, the kitten will be able to respond to a vaccination at 10 or 12 weeks (or older). But studies have shown that about one-third of kittens vaccinated last at 12 weeks of age had no antibodies to Panleukopenia (sometimes called "Distemper" but is actually related to canine Parvovirus) ... i.e. did not respond to the vaccine because of continuing MDA interference.

    What all that means is that most of the vaccine experts (i.e. those who wrote the AAFP Feline Vaccination Guidelines) recommend vaccinating kittens every 3-4 weeks, with the last vaccination at or after 16 weeks of age, when one can be confident that there is no more maternal antibody interference. The most important vaccination is at 16 weeks, but earlier ones are given in case the MDA interference is no longer present at a younger age and one wants to protect the kitten as soon as possible.

    So, the most common vaccination schedule for kittens is at 8, 12 and 16 weeks. If your kitten was vaccinated at 10 weeks, most would suggest vaccinating again at 13 and 16 weeks. You can wait until 16 weeks for the next booster, but your kitten may be vulnerable to disease before then if you wait.

    Be sure that your vet uses a "Modified Live Virus" vaccine for the core vaccination (usually given as a combination shot with Panleukopenia, Herpes and Calici). The other option is a Killed Virus vaccine that is not as protective and requires two doses, both in the absence of MDA intereference ... and Killed Virus vaccines cause a chronic inflammation at the vaccine site that can increase the risk of a cancer developing in some cats that are genetically susceptible. So, be sure your vet uses Modified Live Virus vaccines.

    If Rabies is required by law in your area, it is best to use the recombinant Rabies vaccine (by Merial) which is the only Rabies vaccine that is not Killed Virus. It is usually given at 16 weeks of age or older.

    You may want to look at the 2006 AAFP Vaccination Guidelines. They are currently being updated and should be out by the end of the year. Here is the 2006 version

    Hope that helps.
    Stephanie in Montreal
    Drew Weigner, DVM, ABVP responded:
    I'm not sure where 40 days came from. The next distemper vaccination should be given 3 weeks after the first one. A third one is given three weeks after the second, then repeated once a year (unless a three-year vaccine is used.)

    More importantly, your new kitten should be examined by your veterinarian as soon as possible to make sure he's healthy, especially if the breeder has some type of guarantee with a time limit.

    Drew Weigner, DVM, ABVP
    The Cat Doctor
    Board Certified in Feline Practice

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