Canadian Animal Health Institute

Why Vaccinate?

The Role of VaccinesClick to expand

Vaccines are developed to help provide immunity against disease. Vaccinating animals for disease prevention is common for both pet owners and livestock producers. For our pets, vaccines are administered by veterinarians as part of routine visits.

Veterinarians are able to select from a broad range of vaccines developed to help prevent or reduce the severity of specific diseases that threaten pets.  Your veterinarian is the best person to provide you with guidance on what vaccines are most appropriate and when they should be administered. 

What are Vaccines?Click to expand

Vaccines may contain killed (bacterins) or live bacterial components, inactivated viral components, or modified live viral components which are either alone or in combinations. Some also contain inactivated toxins called toxoids. Vaccines are administered by a variety of methods such as injections under the skin or application into the nostril, all sharing the same goal – to induce some form of immunity against disease.

Many products can be used to provide an immune response. Listed below are these additional classes of immunity-inducing products:

  • Bacterins contain inactivated bacterial components.
  • Toxoids contain inactivated toxins.
  • Antitoxins and antisera contain antibodies against toxins or the germ itself.
  • Polyclonal and Monoclonal antibodies contain antibodies that are specific for various infections.
  • Immunostimulants contain biological substances which stimulate cells involved in the immune response.
How Do These Products Work?Click to expand

They work in different ways. Vaccines, bacterins and toxoids work by urging the animal to ‘turn on’ its own immune system to respond to a specific germ. By giving the animal early exposure to the infectious germ, the animal’s immune system is also stimulated to "remember" the agent and is therefore better able to quickly resist that germ when re-exposed sometime in the future.

Immunostimulants are designed to amplify an animal’s immune response to better deal with an impending disease threat.

Antitoxins and polyclonals contain antibodies already made and are therefore able to provide an instant source of resistance to help minimize the effects of an imminent disease.

Planning Ahead Gives Maximum ProtectionClick to expand

A very important aspect of vaccination is the time between injection and development of protective immunity.

In most cases, with killed vaccines, two primary vaccinations are required to induce a sufficient level of protection and longevity of immunity. The first vaccine, the sensitizing dose, only primes the immune system and rarely induces adequate immunity by itself. A second vaccine, or booster, is required to increase an animal’s level of immunity to the satisfactory level. Most modified live vaccines, however, are able to stimulate the immune response after only one dose in an immunocompetent patient and in the absence of maternal antibodies.

An animal is expected to be immunized a week or two after the booster is administered. In other words, a vaccination program should be completed a week or two before exposure to the particular germ is expected.

Can You Expect 100 Per Cent Protection?Click to expand

Not always. The effectiveness of a vaccine in inducing immune protection can be affected by many variables such as nutrition, stress, and subclinical infection. Whether or not the animal contracts a disease depends on the animal’s level of immunity at the time of exposure compared to the level of exposure to the infectious agent.

In most cases, the increased level of immunity induced by vaccination should be sufficient to fight off the disease. However, animals that are sick at the time of vaccination or under severe stress when exposed to the disease-causing agent, may not mount a protective immune response to any vaccine(s) they are given and may therefore not have sufficient immunity to resist infection.

Supportive Care Helps Maximize ImmunityClick to expand

While a vaccine increases an animal’s level of immunity, it won’t necessarily provide complete protection for your pet. The supportive care that you provide can help to maximize immunity and minimize disease exposure. Supportive care includes good nutrition, proper housing, fresh water and a clean environment.

Are Vaccines Licensed for Use in Canada?Click to expand

All vaccines offered for sale in Canada must be registered with the Canadian Centre for Veterinary Biologics, Canadian Food Inspection Agency. Vaccines are cleared for use only after veterinarians and scientists within this federal government department review data on purity, potency, safety and efficacy.

Vaccine PrecautionsClick to expand

Administering any foreign material always presents some risk of side effects. With vaccines, the risks are often minor and have to be measured against the potential risk of contracting the disease(s).

Here are a Few Vaccine Precautions:

  • Localized swelling or pain may occur at the injection site.  Generally the lump will disappear within 10-14 days. Consult your veterinarian if it persists.
  • Lethargy may be observed for a day or two.
  • In rare cases, animals may become hypersensitive to components in a vaccine. Over-reaction of the immune system may result in a localized reaction or a more serious generalized reaction. Any vaccinated animal should be monitored closely for the first hour after receiving a vaccine or other immune stimulant. If any abnormal reaction is observed, call your veterinarian immediately.
  • Modified live virus vaccines contain components that are safe as long as label directions are followed closely. For instance, "not for use in pregnant animals" demands strict adherence.
  • Animals that are too young should not be vaccinated. Depending on the species and the vaccine, the young animal’s immune system may not be sufficiently developed to respond. In some cases, the mother’s antibodies received by the young animal through consumption of colostrum may interfere with or cancel the effects of a vaccine.

If you have questions on specific vaccines or animal health products, consult your veterinarian.