Why Booster?

A common question from foster parents and new puppy/kitten owners is "why do they need booster vaccines?" Well to start you need to understand how vaccines work. 

Vaccines work by injecting a modified or killed version of the virus it is made to protect against. The goal is for the injection to provide enough antigens of the virus for the body to recognize it as an "invader." The immune system is pretty cool and has the ability to remember past invaders making it stronger against them in the future. So the idea is that a vaccine will initiate that memory to prevent the animal from getting the disease in the future if it comes in contact with the actual virus. 

So then, why do they need multiple boosters? Well the first time an animal is ever vaccinated for a virus the immune system is kind of wimpy with minimal response. It takes about a week for it to become effective and it peaks around 10-14 days but then it disappears. So a second vaccine is needed to initiate the immune response again. This time it responses quicker and the response is much stronger (lasts months to years depending on vaccine). A third vaccine would be even faster and stronger. So this is why even adult animals need at least 2 vaccines about 4 weeks apart for a virus they have never been vaccinated for and then re-vaccinated yearly. 

                                     

Kittens and puppies are a little different because they need more booster vaccines with less time apart. The same idea applies but with kittens/puppies they also have their maternal antibodies that makes things a little more difficult. The youngins are born with maternal antibodies from their mom which are made to help protect them from diseases. These antibodies are awesome for the animal the first couple weeks of life before their immune system is up and running, but they can persist longer than needed and the time they stay is variable in each animal. As long as the maternal antibodies are present the immune system cannot respond to the vaccine. So boosters are given at more frequent intervals in order to assure the animal gets at least 2 vaccines within the time the maternal antibodies are no longer present. What's scary though is that there is a time when the maternal antibodies are low enough to be ineffective at protecting the animal but high enough to make the vaccine ineffective. So this is why you should be really cautious exposing your kittens/puppies to possibly sick animals

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So there's the basic understanding of how vaccines work and why they need boosters. All of the information I provided has come from notes and readings from school (Senior Vet Tech Major at Purdue). 

Talk to your vet about what your pet and foster animals should be vaccinated against. Most shelters and vet clinics have a vaccine protocol they use.

Make sure to vaccinate your pets!