A900
Vaccines

It is important that pet owners establish a consistent health program to reduce the amount of infectious disease present on their premises. All animals are susceptible to many infectious diseases. Infectious diseases can enter a home/yard through new pets or be carried onto a location by other animals and humans. It is important to identify what diseases are a potential problem in the area or in the home. With a veterinarian, a strategy may be formed for protecting against and decreasing exposure of a pet to infectious diseases. A written vaccination schedule should be created and followed. 

The vaccination schedule should be modified as conditions warrant and available vaccines change. It is advisable to develop a complete program of nutrition, sanitation, and health care to help ensure healthy and happy animals.

1. Vaccine: A vaccine is a mixture of killed or modified microorganisms or their parts, administered to help prevent sickness from infectious diseases.
2. Adjuvant: A necessary component of inactivated vaccines, adjuvants are additives to the vaccine suspension which help the body’s immune system recognize the dead virus particles and mount an effective immune response against them. Aluminum salts are usually the adjuvant type seen in commercial veterinary vaccines.
3. Active immunity: Active immunity is obtained when the individual’s own immune system responds to an infectious disease. The active immune response may be stimulated by either the disease itself or a vaccine.
4. Passive immunity: This type of immunity against an infectious disease is obtained by receiving antibodies made by another individual’s immune system. The most common example of passive immunity occurs when a puppy consumes colostrum. Colostrum is the first milk produced by the mother. It is rich in antibodies against diseases for which the mother has immunity. When the puppy nurses from its mother for the first time, it receives passive immunity against those diseases. Over time, however, the maternal antibodies wear out, and the puppy must actively mount its own immune response. Because of this decline in maternal antibodies, it is essential to vaccinate puppies at a young age.

Killed Virus Vaccines:

For a more detailed description on vaccines, refer to the following information.

1. Killed (inactivated) virus vaccines - These vaccines are composed of whole or parts of the killed virus to which the body mounts an immune response. Generally, killed virus vaccines are more stable for storage and less likely to cause the disease being vaccinated against; however, they are more likely to produce vaccination reactions due to the high level of virus particles and the adjuvants that are used.
2. Modified live virus vaccines (MLV vaccines) - These vaccines are composed of living viruses which have been altered to avoid causing the disease being vaccinated against. Despite being changed, these vaccines will still stimulate an immune response by the body. The changing process (attenuation) of these viruses is usually accomplished through repeated culturing of the virus in a tissue to which it is not adapted. Canine distemper virus, for example, prefers to attack lymphoid cells in dogs. To attenuate, or change its nature, CDV was cultured repeatedly through canine kidney cells. The virus adapted to its new life, lost its ability to cause disease (virulence), and can now be given as a vaccine to protect against distemper in dogs. MLV vaccines do not require the use of adjuvants, are less likely to produce vaccination reactions, and stimulate a good immune response with fewer doses than a killed virus vaccine. However, some MLV vaccines have been known to actually cause the disease they are trying to prevent. This occurs when the attenuation or changing process is not complete. Though rare, this has been known to happen with canine distemper MLV vaccines and others to a lesser extent.
3. Conventional MLV vaccines vs. Potentiated MLV vaccines - These terms refer to the modified live versions of parvovirus vaccines currently available. Immunity against parvovirus is particularly challenging to stimulate in puppies that nursed colostrum from their mothers. This is because the passive immunity (from the mother) lasts for an extended amount of time. For that reason, vaccine manufacturers have recently started creating a parvo vaccine with a better ability to penetrate passive immunity from the mother and stimulate an active immune response in the puppy. These new parvo MLV vaccines are known as high titer or potentiated vaccines. Low titer or conventional vaccines are still in use, because they are very effective as boosters in adult dogs. The schedule for parvovirus vaccination depends on the dog’s age, breed, access to colostrum as a newborn, and type of vaccine being used.

Please see the vaccination schedule on page A905 for additional information.