What Every Vet (And Owner) Should Know About Dog Vaccines

Post At A Glance

Are you confused about how often your dog needs vaccines? You’re not alone … your vet probably is too.

At Dogs Naturally vaccine frequency is the number one question we’re asked about. And it’s a good question …. because, as you’ll find out, most dogs are being vaccinated too often. 

And that’s dangerous for your dog.

Core Vaccines For Dogs

Let’s look at core dog vaccines and what the research says about how often they should be given.

But before we do, you should first understand that the core vaccines for dogs (parvovirus, distemper and adenovirus) are not required by law. The only dog vaccine that’s legally required in all US states and some (not all) Canadian provinces is rabies.

So other than rabies, nobody can force you to vaccinate your dog with any other vaccine you don’t want to give.


This is a decision best left up to you and your vet. But before you discuss vaccination with your vet … read on to make sure you know the duration of immunity of those vaccines – and the potentially lethal consequences of over-vaccinating.

Because most vets don’t know how long vaccines protect your dog. (Don’t worry, we’ve got a handout you can share with your vet at the bottom of this post).

Research Into Core Dog Vaccines

When it comes to immunity and duration of immunity for core dog vaccines, there’s one clear expert. Before his recent retirement, Dr Ronald D Schultz was one of three or four researchers looking at how long protection from veterinary vaccines actually lasts – and he did these studies over a 40 year period.

In fact, it’s Dr Schultz’s work that prompted the AAHA (American Animal Hospital Association) and AVMA (American Veterinary Medical Association) to re-evaluate their vaccine schedules

Back in 2003, the American Animal Hospital Association Canine Vaccine Taskforce warned vets that:

Misunderstanding, misinformation and the conservative nature of our profession have largely slowed adoption of protocols advocating decreased frequency of vaccination’; ‘Immunological memory provides durations of immunity for core infectious diseases that far exceed the traditional recommendations for annual vaccination.

This is supported by a growing body of veterinary information  as well-developed epidemiological vigilance in human medicine that indicates immunity induced by vaccination is extremely long lasting and, in most cases, lifelong.

Dr Ronald Schultz And Dog Vaccine Guidelines

“The recommendation for annual re-vaccination is a practice that was officially started in 1978.”  said Dr Schultz. 

This recommendation was made without any scientific validation of the need to booster immunity so frequently. In fact the presence of good humoral antibody levels blocks the anamnestic response to vaccine boosters just as maternal antibody blocks the response in some young animals.”

He added:  “The patient receives no benefit and may be placed at serious risk when an unnecessary vaccine is given. Few or no scientific studies have demonstrated a need for cats or dogs to be revaccinated.

Yet … despite the AAHA’s 2003 comments, they haven’t made any real progress in changing protocols. Their most recent (2017) recommendations are still very tentative:

“Following completion of the Initial Vaccination series and the initial booster dose, MLV and Recombinant Core vaccines will provide a sustained protective response lasting beyond 3 yr.”

This is a very conservative recommendation when you consider the results of the duration of immunity research Dr Schultz and his colleagues did on more than 1,000 dogs, for every major dog vaccine.

Two types of results are in the chart below: “challenge” (meaning exposure to the real virus) and serology (meaning antibody titer results) …

immunity time frame for dog vaccinations

And these numbers show the MINIMUM duration of immunity. The ceilings reflect not the duration of immunity, but the duration of the studies. In other words, if the studies had gone on longer, the research could have shown longer protection … and according to Dr Schultz, possibly for life.

Here’s what Dr Schultz explained …

“It is important to understand that these are minimum DOI’s and longer studies have not been done with certain of the above products. It is possible that some or all of these products will provide lifelong immunity.” 

In 2010, he published the following results on studies with newer generation, recombinant vaccines:

vaccine protection chart

It’s important to note that not only did the vaccines provide protection for a minimum of 4 to 5 years … but they protected 100% of the dogs tested.

Dog Vaccines: The Dangers

Why is it important to understand Dr Schultz’s work? Because your dog’s vaccines can create very real health problems.  

Dog vaccines must be given only when necessary. Every vaccine has the potential to kill the patient or create debilitating chronic diseases including cancer and allergies. Here’s a list of potential adverse vaccine reactions, according to Dr Schultz, based on his research.

common reactions to dog vaccines
moderate reactions to dog vaccines
severe reactions to dog vaccines

And this is what vaccine damage looks like

With many thanks to Patricia Jordan DVM for her photos.

Pictures of dogs with vaccine reactions

Dr Schultz summarizes his 40-plus years of research with the following:

“Only one dose of the modified-live canine ‘core’ vaccine (against CDV, CAV-2 and CPV-2) or modified-live feline ‘core’ vaccine (against FPV, FCV and FHV), when administered at 16 weeks or older, will provide long lasting (many years to a lifetime) immunity in a very high percentage of animals.”

But the problem is, many vets are ignoring this research. If your vet is vaccinating your dog every year – or even every three years – he’s vaccinating too much! Your dog is already protected by vaccines he’s had as a young dog … and any additional vaccine will give him all of the risk with no benefit.

Protect Your Dog From Disease AND From Vaccine Damage

It’s critical to understand that we need to protect our dogs and cats not just from infectious disease, but also from vaccine damage. And in recent years that’s become a lot easier (and a lot cheaper) …

Titer tests are blood tests that can tell you whether your dog has responded to his vaccines and acquired immunity. 

In the past, it’s been difficult (and expensive) to get titer testing done. But for the past few years, vet clinics have had the ability to offer inexpensive in-house titer testing (Vaccicheck and TiterCHEK).

With access to in-house titer testing, there’s never any reason to give any cat or dog over the age of 16 weeks another vaccine without a negative titer test first. So vets don’t have to GUESS at when to re-vaccinate. And with access to these in-house tests, you shouldn’t have to pay high fees to get a titer test for your dog.

But despite these new advances, vets continue to guess anyway … or give vaccines “just in case.” And many clinics still don’t offer these in-house titer tests. So most vets still vaccinate every three years (or even every year in some cases) … and they’re reluctant to use titer tests to avoid potential vaccine-induced health issues.

DNM RECOMMENDS: If you vaccinate your dog, give him Four Leaf Rover’s Protect to balance his gut after vaccination, It’s an everyday soil-based probiotic that contains ingredients that can help remove toxins and heavy metals from his body. Buy Protect now >>

You and your dog rely on your vet to make the right decisions when it comes to vaccines. So please download this printable PDF and discuss it with your vet BEFORE you vaccinate your dog again.


Ronald D Schultz BS MS PhD DACVIM. Vaccination and Changing Protocols – Part 1. IVC Journal. May 21 2014.

Ronald D Schultz BS MS PhD DACVIM. Vaccination and Changing Protocols – Part 2. IVC Journal. September 13 2014.

Smith CA. Are we vaccinating too much? J Am Vet Med Assoc. 1995 Aug 15;207(4):421-5. 

Tizard I, Ni Y. Use of serologic testing to assess immune status of companion animals. J Am Vet Med Assoc. 1998 Jul 1;213(1):54-60. 

Schultz RD. Duration of immunity for canine and feline vaccines: A review. Veterinary Microbiology. 2006;117(1):75-9.

[Presentation to veterinarians ] Schultz RD. What everyone needs to know about canine and feline vaccination programs. 2008 Conference of the AHVMA. 2008. 

[Article] Schultz RD. Dog vaccines may not be necessary. University of Wisconsin-Madison News. 2003 March 14.


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