Sunday, August 10, 2008

Puppies' First Vet Visit

Yesterday the puppies came to work at the vet's office and got their first physical. All of the puppies were healthy, met the physical milestones for their age, and passed their first orthopaedic exam. The only findings that the veterinarian noted were an overbite in White girl, which we had already noticed, and a little bump under the eye of Yellow boy (now wearing a Red collar), which he thinks was probably the result of overlyzealous puppy play! With verification that all the puppies were healthy, I went ahead and gave the puppies their first shot yesterday - the standard first vaccine abbreviated DA2PP which offers combined protection against Distemper, Adenovirus/Hepatitis, Parvovirus, & Parainfluenza. This shot will need to be repeated in another 3-4 weeks by your veterinarian, then 1-2 more times to offer full protection.

So FYI, here's a little tutorial on Puppy Immunology 101 to help you understand more about vaccinations:

In case you've ever wondered, there are very good reasons why puppies must get their vaccinations in a series of 3-4 injections. Puppies receive their first line of protection from antibodies made by Mom - antibodies she made, of course, in response to her own past vaccinations and any previous disease exposures. Mom's antibodies, when passed to the puppies, serve a very important function - they protect the puppies from disease while their own immune systems are too immature to make antibodies on their own. So what exactly do the antibodies do? In a simplified manner, you could say that antibodies bind, or "grab onto" viruses and bacteria, quickly labeling them as invaders so that white blood cells can find, attack, and destroy them before they have the chance to cause disease.

Puppies typically acquire these "maternal" antibodies during the first day or two that they nurse from Mom - thus the reason why you always hear about the benefits of "colostrum", or the antibody-rich "first milk". Over time, the levels of protective antibodies from Mom begin to drop off in the puppies' systems, offering them less and less protection. At the same time, their own immune systems begin to mature and grow in their ability to make antibodies on their own.

So what do vaccines do? Vaccines are typically composed of dead virus & bacteria and/or viruses that have been genetically modified so that they can't reproduce (thus, can't cause disease). The immune system still recognizes these harmless microbes as potentially dangerous foreign invaders and will produce antibodies to protect the body in case it ever encounters them again.

Understanding the function of antibodies and vaccines will allow us to understand the time schedule we use to vaccinate puppies.

If vaccines are given too young, two things will happen:
1) If a puppy has received Mom's antibodies from the colostrum, the maternal antibodies will quickly have the harmless bacteria and/or viruses disposed of by the puppy's system, or,
2) If a puppy did not receive colostrum, the vaccine has no effect because the puppy can't yet make its own antibodies.
Either way, the vaccine is wasted and has no effect on improving the puppy's immune system.

Remember, as a puppy gets older, the antibodies from Mom begin to drop off in number, offering less and less protection. However, at this time, the puppy's immune system is beginning to ramp up. How quickly Mom's antibodies go away and the puppy's immune system gets going varies from puppy to puppy. But by starting vaccines at 6 weeks old, we try to expose the puppies to their first vaccination at a time when we expect Mom's antibody levels, or "titers", to be dropping off in the puppy's bloodstream, while at the same time, the puppy is beginning to be able to make antibodies on its own. When receiving this first vaccination, any remaining antibodies left over from Mom may neutralize some of the effects of the vaccination, but with limited amounts of antibody left, not all of the bacteria & viruses can be found and flagged by the maternal antibodies. Therefore, there is still be some bacteria and/or viruses left for the puppy's immune system to find and make antibodies against - but it won't be a lot, and the puppy's immune system may still not be all that great at making antibody. So we wait and vaccinate the puppy again about 3-4 weeks later. By this point, there should be even less maternal antibody remaining and at the same time, the puppy's immune system can make antibody more efficiently. We continue vaccinating the puppy until the time when all maternal antibody should be gone and the puppy's immune system has nearly reached its peak performance, typically around 16 weeks of age. At this point, we can feel confident that a puppy is fully protected against the disease we have vaccinated against.

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