admin | 2:51 pm | March 8, 2008 | Vaccination
VACCINATION FACT SHEET[1]
Vaccinations as a Component of Comprehensive, Individualised Care
For many years, the practice of veterinary medicine has benefited from the annual administration of vaccines. By encouraging dog owners to bring their pets in yearly for vaccinations, veterinarians have been able to recognize and treat disease earlier than might otherwise have been the case. and to inform clients of important aspects of canine health care. They have also prevented epidemics of disease and so vaccination is a very important part of disease prevention and every dog should be vaccinated, but it is not essential to vaccinate every year.
However each dog’s vaccination needs should be assessed at least yearly and modified on the basis of changes in your dog’s age, health status, home and travel environment, and lifestyle. Your vet should explain the potential benefits and risks of vaccination and assess their suitability for your dog given its lifestyle and risk of exposure.
The Immune System as it Applies to Vaccination
Understanding the immune system provides a basis for understanding the nature of vaccine immunity. Two major types of immunity prevent or limit infectious diseases: nonspecific (innate) immunity and specific (adaptive) immunity.
In nature, it is innate immunity (including skin, hair, tears, normal microbial flora, and mucus and acidity of the gut) that prevents a majority of disease causing agents from infecting and/or causing disease in animals.
Adaptive immunity is characterised by being specific and having memory, and is the type of immunity stimulated when an animal receives a vaccine. This specific immune system response is comprised of:
1. Humoral (antibody) immunity, where B lymphocytes (plasma cells) produce the four immunoglobulin classes: IgG, IgM, IgA, and IgE; other cells (phagocytic cells and effector molecules) also play an important role.
2. Cell-mediated immunity (CMI) is comprised of T lymphocytes and their effector molecules, including T helper cells, T regulatory cells, T cytotoxic cells, macrophages, and a number of products of the cells called cytokines.
The Immune Response to Vaccination or Infection
When an animal is vaccinated or infected, the immune response includes cloning of antigen-specific T and B cells that serve as effector cells for immediate protection and memory cells that provide long-term immunity.
The effector cells themselves are usually short lived, dying in days or weeks after stimulation.
Memory cells, on the other hand, survive for years, often for the life of an animal for some vaccines and infections. Memory T and B cells and the antibodies produced by long-lived memory effector B cells cooperate to provide protection from challenge at a later time in life for the vaccinated animals that come in contact with the disease causing agent.
Available information suggests that vaccine protection from infection and/or disease in the dog is regulated primarily by humoral immunity and secondarily by cell-mediated immunity. This finding is particularly true when vaccination is known to prevent reinfection (sterilising immunity). This is the ultimate form of immunity because disease cannot develop when infection is blocked or infection is significantly limited. Sterilising immunity occurs after effective vaccination (protection) against certain pathogens such as distemper, infectious canine hepatitis, and canine parvovirus.
However, when vaccination fails to protect against infection and instead protects against the development of clinical disease (as is the case for Canine parainfluenza “kennel cough” vaccination), cell mediated immunity and humoral immunity both play a critical role in preventing or reducing the severity of disease—not by preventing infection but by limiting its effects or keeping the infection localised.
It is essential to note that the mechanism of protective immunity in a vaccinated dog is very different from immunity in an unvaccinated naive dog. Antibody is usually present in a vaccinated dog and functions to limit or prevent infection. It is never present at the time of infection in an unvaccinated, naive animal. Furthermore, cell mediated and humoral immunity due to memory cells is stimulated in minutes to hours when a vaccinated animal is infected (called an anamnestic response); whereas it takes days or weeks (primary response) to be stimulated in a nonvaccinated, immunologically naive dog.
Antibody Titre Tests to Monitor Immunity
In a vaccinated animal, antibody plays the primary role, because it prevents infection (sterilizing immunity) or limits the infection, and CMI plays a minor role. If infection occurs, antibody increases rapidly and restricts infection .
The presence of serum antibodies to an infectious agent-even if detected months or years after vaccination, indicates that the animal has the memory cells required for a rapid anamnestic cell-mediated and antibody response if the animal is exposed to the same infectious agent at a later time.
How then should antibody titers be used to monitor vaccine immunity? They can be helpful in the following ways:
• to determine if there has been an immune response following vaccination
• to determine the duration of immunity
• to ensure the vaccine is immunogenic
• to know precisely when to vaccinate a puppy
• to determine whether the animal is a “low or nonresponder” to certain vaccines
Although the Canine Vaccination Task Force committee does not feel it is necessary to determine titers to core viruses on an annual basis because of the long minimum duration of immunity, titers can be used for your assurance that an animal has immunity.
Experience with postvaccination titers for Canine Disteper Virus, Canine Adenovirus, and Canine Parvovirus shows that sterile immunity lasts for years; thus, if the test is positive 1 year after vaccination, it is likely to be positive >3 years after vaccination.
PUPPIES
If the test is negative, then you should revaccinate again immediately. If the test is not positive shortly (>2 weeks) after the final vaccination, it suggests that the animal was not immunised. If you waited until 1 year of age, as we do now, the animal would potentially be susceptible during the most critical time in its life, the time when the animal needs to have vaccine immunity. Experience with the Titre test demonstrates greater than 90% of the dogs tested after the puppy series and up to 3 years after vaccination are positive, an indication they have sterile immunity and don’t need to be revaccinated with core vaccines.
[1] Report of the
admin | 2:53 pm | | Vaccination
Canine Vaccination Protocol
Revised 10/03 (Adapted from protocol of Dr Jean Dodds)
For dogs susceptible to or affected with immune dysfunction, immune-mediated disease, immune-reactions associated with vaccinations, or autoimmune endocrine disease (e.g., thyroiditis,
| Age of Pups |
Vaccine Type |
| 9 weeks |
MLV Distemper/Parvovirus/ Adenovirus only |
| 12 weeks |
MLV Distemper/Parvovirus/Adenovirus only |
| 16-20 weeks |
MLV Distemper/Parvovirus/Adenovirus only |
| 1 year |
MLV Distemper/Parvovirus/Adenovirus only booster |
After 1 year, annually measure serum antibody titers against specific canine infectious agents such as distemper and parvovirus. This can be done on a rotating basis. This is especially recommended for animals previously experiencing adverse vaccine reactions or breeds at higher risk for such reactions (e.g., Weimaraner,