A900
Vaccines

It is recommended that vaccines should be administered by a local veterinarian. This is because veterinarians have access to superior vaccines and can handle problems that may arise from vaccine reactions. The veterinarian can also ensure that proper administration techniques are followed. However, if individual situations require that the vaccine be given at home, the following general suggestions are a must:

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.

Terms:
  1. Vaccine: A vaccine is a mixture of killed or modified microorganisms or their parts, administered to help prevent sickness from infectious diseases.

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  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 kitten 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 kitten 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 kitten must actively mount its own immune response. Because of this decline in maternal antibodies, it is essential to vaccinate kittens at a young age.

  5. Viral vaccines:
  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. 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.
Killed Virus Vaccines:

Advantages
  • Usually safe for pregnant animals
  • Stable in storage

Disadvantages
  • Multiple doses required
  • Weaker immune response

  • Shorter duration of immune response

  • Adjuvants may cause reactions
  • Hypersensitivity reactions are more common
 Modified Live Vaccines:

Advantages
  • One dose required
  • Faster immune response
  • Stronger and more durable response
  • Fewer post-vaccination reactions

Disadvantages
  • Not recommended for pregnant animals
  • Possible viral shedding to other animals
  • Improper handling may inactivate the vaccine

 
  1. Bacterial vaccines-
  1. Bacterins - Bacterins are killed whole bacteria or their parts. Some of the bacterin vaccines are among the most notorious for producing vaccination reactions. Like the killed virus vaccines, bacterins are unlikely to cause disease through retained virulence (ability to cause disease) and are more stable for storage.
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  2. Avirulent live bacteria (AVL) - Bacteria can be made avirulent (non-infective) through different mechanisms. Some of these mechanisms include gene manipulation and culture under abnormal conditions. AVL vaccines are uncommon in veterinary medicine, although they do exist for small animals, especially for intranasal use.
  1. Fungal vaccines - These vaccines are used to prevent fungal infections and the most common fungal vaccine for cats is used to prevent Microsporum canis (see page C230 for more details).

  2. Toxoids - This is an inactivated toxin (poison), administered to stimulate the body’s immune response against the poison itself, rather than against the organism which produces it. Probably most common is the tetanus toxoid. Due to the delay in producing an immune response, toxoids are used in prevention rather than treatment. Toxoids are also used because of their long-lasting effect.

  3. Antitoxin - An antitoxin is purified serum from another individual, containing antibodies against a toxin. Antitoxins do not produce an immune response and are not technically vaccines. They provide immediate protection against a toxin and are given for treatment of existing disease, rather than for long-lasting prevention. Antitoxins which are used in veterinary medicine include tetanus antitoxin and rattlesnake venom antitoxin. Antitoxins are a form of passive immunity.

  4. Antiserum - This is purified serum from another individual which contains antibodies against different organisms (bacteria or viruses). Antiserum is another form of passive immunity.

Note: The feline leukemia, panleukopenia, rhinotracheitis, calicivirus, and chlamydiosis vaccines often come combined as one injection known as a "mixed" or "cocktail" vaccine.

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