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 Puppy and Kitten Vaccinations 
Why so many different recommendations?

What's a booster shot?  Why are some puppy or kitten vaccinations given one or two times and other pets get a shot four times?  How long does a vaccine last in a puppy.  Aren't we over-vaccinating?

Find out more about the how and why
 of vaccinations in dogs and cats.

Kitten and cat health care questions and answers, articles, videos and images


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If your pet is sick, call your local veterinarian immediately

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     I've owned and bred dogs for years and I still don't know what goes on with these "puppy shots".  Why do some of my pups get two or three sets of  "puppy shots" every 3 to 4 weeks and other pups only get a series of one or two shots?
Answer:  puppy shots... vaccines... immunity
     This can be confusing and many puppy or kitten owners simply do as their veterinarian recommends.  Essentially, in any animal or human one cannot simply look at the individual and determine their immune
Vaccines have prevented disease in countless humans and animals competence to any particular disease.  There are "titer tests" to measure quantity of circulating antibodies to disease but the results of these tests are not a significant assessor of overall immune strength.  There is much more to having a  healthy immune function than circulating antibodies.
     For example, cellular immunity, the inherent self-protective status of each cell, plays a huge roll in immune function and disease prevention, and is very difficult to measure before or after a vaccine is administered or an actual disease is encountered.  Humoral immunity present in body fluids such as the lymphatic and intracellular fluid plays a role in overall immune health but, again, there is no accurate way to measure it.
LT - 031610 - 125x125 F&T
    If you scroll down to the graphics it will help to visualize why pets receive one or more in a series of "shots" when they are young.  Many veterinarians suggest starting a vaccination series in puppies and kittens when they are about 6 weeks of age.  The vaccinations often include several different disease antigens in one dose.  Because we can't be sure that a single vaccination episode will truly initiate a protective level of immunity, follow-up vaccinations are recommended until theYoung puppies can be susceptible to all sorts of pathogens. pet is about 16 weeks of age.  Almost every individual will have a good response to a vaccine given at 16 weeks of age... this means they will have active immunity.
     The antibodies they obtained with the mother's first milk (colostrum) is referred to as passive immunity because it doesn't last long and passes away by 16 weeks of age.  Now the pup or kitty is without protection until some sort of exposure occurs.  Let's hope that exposure is from a vaccine and not the real, virulent disease organism! 
     If maternal antibodies are present in the puppy or kitten at the time the vaccine is administered the vaccine antigens will be neutralized by those maternal antibodies!  The vaccine will not stimulate immunity.  We want to vaccinate as soon as the maternally derived passive immunity has disappeared, which could occur any time between birth and 16 weeks of age.  Because it is unknown what level of passive immunity (maternal antibodies) is present in puppies and kittens at any given time before 16 weeks of age, we try to vaccinate at reasonable intervals to trigger an active immunity as soon as the individual has no more maternal antibodies.  Once maternal antibodies are gone dogs and cats are vulnerable to all sorts of pathogenic organisms such as parvovirus, rhinotracheitis, borrelia and leukemia.

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Vaccines are neutralized by the pup's passive immunity Some human reared pups and kittens are immune challenged. Healthy nursing pups will eventually need vaccinations A booster vaccine is the same one given previously but a new dose boosts an already present immune level.
Colostrum, the first milk obtained from the mother, is rich in immune substances Hand reared pups often miss out on the passive immunity in colostrum Maternal immunity is transferred to pups via the first milk produced... called colostrum. Older dogs and cats may need yearly boosters to protect against specific diseases.

FYI... intelligent and credible info about pet vaccines are linked to below:

Over-Vaccination Topic AAHA VACCINATION
Research by Dr. Ronald Schultz, professor and chair of pathological sciences in the School of Veterinary Medicine, U of Wisconsin ASPCA VACCINATION  GUIDELINES View an animal hospital's suggested vaccine

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The vast majority of vaccine administration will be effective in preventing disease.
Vaccinations "prime" the immune systems to be ready with defense mechanisms

CLICK TO ENLARGE: Passive Immunity Chart for puppies and kittens

View a chart depicting immune status in a puppy that received abundant
passive immunity from the mother's colostrum


Kitten with eye infection
We do not have vaccines for every known pathogen

CLICK TO ENLARGE: Passive Immunity Chart for puppies and kittens

View a chart depicting immune status in a puppy that received a modest amount of
passive immunity from the mother's colostrum


Each pup in any litter has individual characteristics
 Passive immunity will not be present in pups older than 16 weeks of age.

CLICK TO ENLARGE: Passive Immunity Chart for puppies and kittens

View a chart depicting immune status in a puppy that received very little
passive immunity from the mother's colostrum

Learn the difference between:
   Passive Immunity is obtained from maternal antibodies present in colostrum and provides short term immunity.

   Active Immunity is generated when an antigen generates a response in the immune systems.  Active immunity is long term (sometimes life-long) and can be acquired by surviving an exposure to a pathogenic organism.  The exposure can be from a vaccine or from exposure to the free antigen in the environment.

   Immunological memory occurs after exposure to a specific pathogen and describes an enhanced response to future encounters with that same pathogen.

  Learn more about immune functions, active vs passive immunity, vaccines, and pathogens here.

     Animals, just like humans, can have an adverse reaction to any vaccine.  These responses are always a surprise because we have no practical way to predict them... the first time.  However, once an individual displays an adverse response to an antigen, and who's to say it was either x, y or z antigen in a multivalent inoculation, there is a high probability for another adverse event if the same antigen is inoculated again.  You and your veterinarian should have a thorough discussion about the pros and cons of revaccinating an animal that has had a reaction to a vaccine.
This reaction is NOT due to a vaccine This reaction occured right after a vaccine was administered
Within seconds of eating a single peanut this pup developed a urticarial reaction Within a few minutes after being vaccinated this dog developed a urticarial reaction

Doctor's Notes
     The goal of vaccinating an animal is to stimulate immunity in the animal with a non-disease producing antigen and do this before an actual exposure to the real disease producing antigen is encountered.  This way the individual's immune systems, including cellular immunity and circulating antibodies, are already on guard to eliminate invaders before they get a chance to multiply and harm the individual.

View all topics  View the University of California at Davis 2011 Vaccination Protocols

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Data below is taken from the AAHA 2011 Vaccine Recommendations

This data applies to “noninfectious vaccines”… which are killed, inactivated, dead, conventional and recombinant subunit plasmid DNA vaccines.  The Veterinary Medicine Clinic at U. of California, Davis, displays their vaccine protocols for dogs and cats here.

This is the first group of two kinds of vaccines... not all vaccines are created equal!

The noninfectious (inactivated, killed) vaccines include:
killed viral rabies virus [RV],
canine influenza virus [CIV], and canine coronavirus [CCoV]),
whole killed cell bacterins such as Lyme, Leptospira,
bacterial subunit (recombinant outer surface protein A [OspA] Lyme
subunit Leptospira outer membrane component [OMC],
a cellular antigen extract of the Bordetella bronchiseptica (Bb) vaccine,

Initial Vaccination
Most noninfectious vaccines require at least two initial doses to immunize, regardless of the dog’s age. The first dose of a noninfectious vaccine generally primes the immune response and the second dose, which should be administered 2–6 wk later, provides the protective immune response. Immunity typically develops approximately 7 days after the second dose.  Therefore, the minimum time for onset of immunity is approximately 3 wk after administration of the first dose of a noninfectious vaccine.

When the interval between the initial two doses of a noninfectious vaccine exceeds 6 wks, it is recommended the dog be revaccinated, administering two doses, 2–6 wk apart, to ensure protective immunity has developed.

Minimum Age at the Time of Initial Vaccination Administration of a noninfectious vaccine to a dog 12 wk of age may be blocked by maternally derived antibody (MDA). A second dose, even if given after 12 wk of age, would not be expected to immunize the patient (rabies being the exception). To ensure that puppies are effectively immunized, it is recommended that the first vaccine dose in the initial series of most noninfectious (inactivated, killed) vaccines be administered not earlier than 12 wk of age. {This assumes maternal antibodies are still present! Veterinarians may assume maternal antibodies are not present and therefore begin inoculations at 6-7 weeks of age. TJD} Among orphans or those puppies that are known not to have received colostrum, the first dose of a noninfectious vaccine may be administered as early as 6 wk of age.

Missed Dose—Initial Series 
When administering a noninfectious vaccine for the first time in the life of a dog, at least two doses, administered 2–6 wk apart, is recommended. If the interval between the first two doses exceeds 6 wk, it is recommended that two additional doses be administered at an interval of 2–6 wk, thereby insuring that both immune priming and {anamnesis TJD} immunization occur.

Missed Dose—Adult Booster
Because noninfectious vaccines generally have a duration of immunity (DOI) that is shorter than infectious vaccines, annual (JAAHA | 47:5 Sep/Oct 2011) revaccination ("booster") is commonly recommended. {Except for some serovars of Leptospirosis in specific animals. tjd}

A dog that failed to receive a noninfectious vaccine at the recommended interval of 12 mo is unlikely to maintain protective immunity for the same length of time (years) that occurs after administration of infectious viral (core) vaccines. At some point beyond 12 mo, administration of a single dose of a noninfectious vaccine may fail to induce a protective immune response (due to loss of immunologic "memory") {How is immunologic memory measured in a manner that we can determine the dog is now susceptible to natural exposure induced disease or will not undergo an anemnestic response? TJD} In such cases, administration of two doses, 2–6 wk apart, may be required to immunize.

However, intervals defining when two doses versus one dose would be required to immunize have not been established. Specific intervals {will vary, depending on: (1) the vaccine, (2) the patient’s (intrinsic) immune response, (3) time elapsed since administration of the last dose, and (4) total lifetime doses the dog received.  The decision to revaccinate a dog with two doses versus one dose is left to the discretion of the veterinarian.  The following general guidance is offered for dogs that are overdue for a noninfectious vaccine and are considered to be at risk for exposure:

Leptospirosis: limited studies have been conducted to assess immune response to a single dose of vaccine in dogs that have not received a booster vaccination in >12 mo. Among dogs with a high risk of exposure, it is reasonable to consider administering two doses of vaccine, 2–6 wk apart, if the interval between doses exceeds 24 months (2 years).

Lyme disease: only limited unpublished studies have been performed to evaluate the immune response to a single dose of vaccine in dogs that have not received a booster vaccinatio in >12 mo. Although a single dose of Lyme vaccine given years after the initial doses can raise antibody levels, the protective quality of these antibodies has not been confirmed {nor shown to be insufficient: TJD} by challenge.   Among dogs with a high risk of exposure, it is reasonable to consider administering two doses of vaccine, 2–6 wk apart, if the interval between doses exceeds 2 years.

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