How do Pet Vaccines work?

Effective vaccines can give you peace of mind when it comes to the good health of your pets. In fact, many states and municipalities require proof of immunization for dogs and cats.

However, you may wonder how veterinary vaccines work. What’s the difference between live and killed immunizations? What do IM vs SQ injections mean?

In this article, we’ll aim to answer these questions and more.

Vaccine Basics

First, let’s look at a brief overview of vaccination basics. This explanation is from NOAH, a UK animal rights organization:

“Vaccines work by stimulating an immune response in an animal without causing the disease itself. When healthy animals are vaccinated, their own immune system responds to the vaccine and can remember the infectious agent to which the animal is vaccinated. This means, if appropriately vaccinated animals are then exposed to the pathogen against which they have been vaccinated, they can expect a level of protection from disease.

Some vaccinations, like Rabies, are government mandated for public safety.

There is also a standard vaccination schedule for puppies and kittens which include immunizations against distemper, parvo, hepatitis, and other dangerous diseases.

These are the “core” vaccines that veterinarians recommend for nearly all pets. Then, your dog or cat will need boosters periodically throughout their lives.

Pet Vaccines

Beyond the core vaccines, your veterinarian will recommend other vaccines based on your pet’s age, health, and lifestyle. For example, dogs who go to doggie daycare or regularly interact with other animals are recommended to be up-to-date on their Bordetella and Canine Influenza vaccines.

Each pet will have an individualized vaccine protocol.

Now, let’s look at some of the vaccine terms you’ll hear, like IM vs. SQ and killed vs. live vaccines. What do they mean?

What are IM and SQ Injections?

You’ve probably never thought about where the vaccines are given, yet it turns out there are different places where they can be injected.

  • “IM injection”: means an intramuscular injection. This injection goes into the muscle. The muscles have good blood flow, so when the injection is properly executed, they’ll absorb the medication quickly. (Source)
  • "SQ injection": means a subcutaneous injection. This injection goes under the skin but not directly into the muscle. The vaccine is usually absorbed slower than an IM injection. Many live vaccines are administered this way.

What’s the Difference Between Live and Killed Vaccines?

There are different types of vaccinations, two of which are “live” and “killed” vaccines.

  • “Live” vaccines: These vaccines have a weakened version of the disease, known as a pathogen. When your pet receives this type of vaccine, the pathogen causes your pet’s body to stimulate a response but does not cause the disease.
  • "Inactive" or "killed" vaccines: Also contain the pathogen, but rather than simply a weaker version, they no longer have any ability to infect your pet.

Both improve the immune response and protect against a specific disease. According to the American Animal Hospital Association, “The immunizing virus/bacteria in a ‘noninfectious’ vaccine is not capable of replicating within the host after administration. All inactivated (killed) viral vaccines and bacterial vaccines are noninfectious."

The Importance of Vaccines to Your Pet's Health

Vaccines are important for your pet’s health. When puppies and kittens are first born, they have limited protection against diseases like parvo and rabies. That protection weakens and disappears within the first few weeks of their lives.

That’s why veterinarians have a standard approach to “puppy shots” and “kitten shots” when pets are young. As they get older, they’ll require “booster” shots at regular intervals which your veterinarian will discuss with you.

In addition to protecting your pet’s health, most local ordinances require proof of immunization against diseases like rabies. Besides keeping your pet healthy, immunizations are also cheaper than treatment.

Is your pet up-to-date on their vaccines? Reach out to us to find out!


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