Pet Vaccines – What Are They

And How Do They Work

Vaccines have an amazing role in pet (and human) health. But they’re not without risk.
Let’s take a look at how vaccines work.

Vaccination involves injecting the ‘host’ (pet) with a virus.
The immune system is designed to fight foreign invaders, to protect against disease and resulting death.
Vaccines contain a small amount of a target virus. Small enough to not overwhelm the immune system. Large enough to be detected by the immune system and trigger a response.

This detection–response forms an immune system memory. This way it knows how to respond to that specific virus with antibodies that will destroy it.
That’s considered to be “immunity”.

Whether or not this happens successfully depends on both the pet and the vaccine.

The Pet

For the best results your pet should not be immune–stressed in any way. As you know in your own life you’re more likely to catch a cold or flu if you’re already run down or sick. In other words, if you’re immune–stressed.

If your pet is weak, sick, malnourished, receiving drugs or is having or recently had surgery such as spaying or neutering, he’s immune–stressed. Considering delaying any vaccination until your pet is stronger.

The Vaccine

There are two vaccine forms:
– Killed virus
– Modified Live Virus (MLV)

Killed virus uses a non–active (killed) virus.
Rabies vaccines are killed virus.

Modified Live Virus uses an active virus. It’s chemically altered (modified) to be less virulent.
Formaldehyde – a known carcinogen – is typically used to alter the virus. There’s no guarantee it will completely alter it; therefore, one risk is the vaccine will create the disease it’s designed to prevent.

“Adjuvants” can also be added. Adjuvants are foreign proteins that create a non–specific immune response. They’re used as a type of insurance… if the body doesn’t produce a strong enough immune response to the virus, it will hopefully produce a strong enough response to these other foreign particles.
Adjuvants are nearly always added to Killed virus vaccines and often to MLV vaccines.

Vaccines most often come in multi–dose vials. It’s more cost effective.
So a preservative is added. Typically thimersol (49% mercury) and aluminum – both carcinogens.

There can be some additional foreign proteins… the virus is typically “grown” on beef, chicken or duck tissue. Some tissue may get into the vaccine. And of course your dog or cat is none of those animals… so it’s foreign tissue.

Nature Versus Needle

A virus injected under the skin bypasses two defensive organs… the skin and the nose. The skin can keep bacteria out and mucous membranes in the nose can filter and block bacteria.

With an injected vaccine you’re bypassing these defenses and putting a larger load on your pet’s immune system. By overwhelming the immune system you can get a hyper–response which can lead to an autoimmune disease and/or an over–sensitivity resulting in allergies.

Also in nature you’re likely to encounter one virus at a time. To make vaccinating more “convenient”, vaccines come in combinations of 2–6 strains per dose. It’s obvious when you think about it – fighting one “bug” is much easier than fighting multiple bugs.

When Vaccinating Consider…

  • Delaying vaccination if your pet is sick, weak, malnourished, receiving drugs or is having or recently had surgery
  • Using single dose vaccines when possible (they don’t require a preservative)
  • Using single strain vaccines or at least minimizing the number of strains per application



Natural Dog and Cat Care 101 explains the history of vaccination for cats and dogs, the risks, the current science and recommendations from leading Vets. Get the best information to make the wisest care choices.

Dog and Cat Vaccination Articles


Current Thinking on Dog and Cat Vaccinations

You probably got a polio vaccination when you were a kid. Do you get a “booster” every year?
Me neither.
So what’s up with annual vaccinations for dogs and cats?
Well the short answer is:
It’s based on established custom… NOT science.
AND it’s NO LONGER recommended.

Dog Vaccinations – Current Best Practices

There’s two parts to a vaccine protocol for your dog.
– Which vaccines
– How often
Learn about the current best practices?

Cat Vaccinations – Current Best Practices

Yearly vaccinations became customary back in the 1950’s, more so for dogs than cats. While there wasn’t any scientific research to justify the annual re–vaccination, neither were there any known risks at the time.

That has changed… dramatically. It’s now known there are many serious adverse reactions to vaccines.


Vaccinating dogs and cats