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What Are Vets Not Telling You About Dog Vaccines?

Delve into the hidden risks and lesser-known facts about dog vaccinations, and discover how to protect your pet from potential adverse effects.

vaccine adverse effects in dogs


  • According to a recent study, pet parents who are hesitant to revaccinate their animals due to the potential for adverse events may be impacting the mental and physical health of veterinary staff; however, the fact is that owners are also mentally and physically impacted when they are pushed to revaccinate in order to have their pets cared for medically
  • A 2023 large-scale study of vaccine adverse events in dogs revealed that certain categories of dogs are at higher risk for vaccine adverse events than others, including small dogs, certain breeds, spayed females, dogs around 1 year of age, and those receiving multiple vaccines in a single visit
  • In addition to immediate adverse reactions to a vaccine, there is the potential for vaccinosis, which is characterized by a chronic reaction to not only the altered virus contained in vaccines, but also to the chemicals, adjuvants, and other components of tissue culture cell lines as well as possible genetic changes that can be induced by vaccines
  • An obvious solution to this issue is to make vaccine titer tests — not automatic revaccination — the standard of care for veterinary practices; this is a “first, do no harm” approach that can be embraced by both sides of the argument, especially if the veterinary community works to make the tests available, and more importantly, affordable for pet owners
  • In the meantime, there is much you can do as your pet’s primary advocate to ensure your dog’s risk of adverse vaccine reactions is minimal

Recently I read an article in the veterinary publication Clinician’s Brief about the potential for vaccine adverse effects in dogs. The article begins:

“Adverse effects (AEs) of vaccines are a significant concern with emerging trends in vaccine hesitancy and avoidance. Fear of AEs is often anecdotally noted as a reason clients seek new clinicians and limit visits to the clinic. Vaccine hesitancy can impact mental and physical health of veterinary staff.”1

I find it troubling that the article’s author, veterinarian Dr. Jaron Hanson, positions pet owner fears about vaccine adverse events as “anecdotal” (i.e., subjective, hearsay, unreliable, untrustworthy), while at the same time stating as fact that “vaccine hesitancy can impact mental and physical health of veterinary staff,” complete with a footnoted reference to a 2023 study in the journal Vaccine.2

In my experience, dog parent fears about vaccine adverse events impact their mental and physical health, especially when they’re refused veterinary care for a pet unless and until they submit to the vaccine schedule established by the clinic staff. There’s a simple solution to this problem, which I’ll discuss shortly.

Dogs at Highest Risk for Vaccine Adverse Events

The Clinician’s Brief article discusses a 2023 study in the Journal of the American Veterinary Medical Association (JAVMA) that concluded the risk of vaccine adverse events in dogs is increased in certain breeds, smaller dogs, and those receiving multiple simultaneous injections.3

The study covered a five-year period from January 1, 2016, through December 31, 2020. Electronic medical records of over 4.6 million dogs at over 1,000 veterinary clinics associated with a corporate practice (Banfield) were analyzed for diagnoses of possible AEs reported within three days of vaccine administration that did not also include concurrent injectable heartworm preventives.

The researchers focused on patient risk factors including age, sex, breed, and weight, and the number and type of vaccines given. The results revealed that:

  • Small dogs under 11 pounds are at higher risk for AEs following vaccination
  • A dog’s breed seems to play a role — French Bulldogs, Dachshunds, and Boston Terriers had higher AE rates than other breeds (including mixed breeds), whereas Golden Retrievers, Labrador Retrievers, and German Shepherds had lower rates
  • Female dogs, particularly spayed females, are more likely to experience AEs compared to intact males
  • Young dogs, especially those around 1 year of age, have an increased risk of AEs, possibly related to booster vaccinations
  • AEs increase with the number of vaccines given at a single visit, with the risk of an AE increasing by about 25% with each additional vaccine up to four vaccines
  • Certain types of vaccines are linked to higher AE rates — the rabies vaccine has a higher moderate to severe AE rate than other vaccines, vaccines against leptospirosis and Lyme trigger mild reactions

Immediate Vaccine Adverse Events vs. Vaccinosis

The condition of vaccinosis isn’t recognized by most conventional veterinarians and isn’t something many pet parents are familiar with, either. But first, let’s talk about what vaccinosis isn’t.

It isn’t an acute, often immediate adverse reaction to a vaccine, such as the following “common and mild” reactions as described by the American Veterinary Medical Association (AVMA):4

  • Discomfort and local swelling at the vaccination site
  • Mild fever
  • Decreased appetite and activity
  • Sneezing, mild coughing, "snotty nose" or other respiratory signs may occur 2-5 days after your pet receives an intranasal vaccine

It also isn’t the following “less common and more serious” reactions:

  • Persistent vomiting or diarrhea
  • Itchy skin that may seem bumpy ("hives")
  • Swelling of the muzzle and around the face, neck, or eyes
  • Severe coughing or difficulty breathing
  • Collapse

Adverse events, or hypersensitivities, whether mild (such as lethargy, flu-like symptoms, etc.), or severe (such as anaphylactic shock), that are clearly linked to a recent vaccination are widely acknowledged by the conventional veterinary community. They’re viewed as occasional aberrations of a basically safe procedure.

Vaccinosis, on the other hand, is a problem only holistic and integrative veterinarians are willing to acknowledge, however, many conventional vets have become more open minded about the concept since prominent health organizations have acknowledged ongoing potential COVID vaccine side effects.

It’s a reaction of a pet’s body to vaccines that have been injected without the pet having experienced a notable adverse event or hypersensitivity. These are chronic reactions to not only the altered virus contained in the vaccine, but also to the chemicals, adjuvants, and other components of tissue culture cell lines — as well as possible genetic changes — that can be induced by vaccines.

Dr. Richard Pitcairn, who holds a PhD in immunology and is also a world-renowned expert and educator in veterinary homeopathy, as well as author of the handbook of holistic health care for pets, “Dr. Pitcairn's Complete Guide to Natural Health for Dogs & Cats,” defines it this way:

“Vaccinosis is to be understood as the disturbance of the vital force by vaccination that results in mental, emotional, and a physical change that can, in some cases, be a permanent condition.”5

According to Pitcairn, vaccines intended to protect pets against acute natural diseases create chronic conditions with features of the disease the vaccine was supposed to prevent. This transformation happens in the laboratory, where natural viruses are modified to make vaccines.

Where the natural virus would trigger a strong immune system response, the modified lab-created virus in the vaccine doesn’t elicit much of a reaction by the animal’s immune system. Instead, it holds the potential to create chronic changes in the body that can lead to disease.

The delivery of a vaccine is also very different from how a natural disease develops in an animal’s body. Vaccines contain several potentially reactive substances, including heavy metals, mutated bacteria/cell cultures, immune irritants6 (adjuvants), foreign proteins, and chemical preservatives.

All these toxins are delivered by injection directly into the blood and lymph, bypassing the usual first lines of defense, including the skin, nose, mucous membranes, saliva, and so forth. So not only is the lab-modified virus in the vaccine unnatural, the way it enters an animal’s body is also very unnatural. When you look at the situation from this perspective, it’s easy to see how abnormal immune reactions can be triggered by vaccinations.

Symptoms of Vaccinosis


  • Lethargy
  • Stiffness
  • Hair loss
  • Lack of appetite
  • Hair color change at injection site
  • Conjunctivitis
  • Fever
  • Sneezing
  • Soreness
  • Oral ulcers


  • Immunosuppression
  • Granulomas and abscesses
  • Behavioral changes
  • Hives
  • Vitiligo
  • Facial swelling
  • Weight loss
  • Allergic hypersensitivity
  • Reduced milk production (females)
  • Respiratory disease
  • Lameness
  • Allergic uveitis


  • Injection-site sarcomas (cancer)
  • Glomerulonephritis
  • Anaphylaxis
  • Myocarditis
  • Autoimmune arthritis
  • Encephalitis or polyneuritis
  • Polyarthritis
  • Seizures
  • Hypertrophic osteodystrophy
  • Abortion
  • Autoimmune hemolytic anemia
  • Congenital abnormalities
  • Immune-mediated thrombocytopenia
  • Embryotic (fetal) death
  • Thyroiditis
  • Infertility

Titer Testing Can Protect Pets from Vaccine Damage

My vaccination protocol is to administer a first round of puppy shots (distemper, parvo, adenovirus) or kitten shots (panleukopenia, calici, herpes) before 12 weeks of age, usually around 9 to 10 weeks. I give the second round between 15 and 16 weeks. Two weeks after the second round, I do an antibody titer (via a simple blood draw) to ensure the animal has been immunized and not just vaccinated.

A simple solution that can erase the stress felt by both pet parents and veterinary staff who hold conflicting opinions about the need to revaccinate is to make affordable titer tests, not automatic revaccinations, the standard of care in veterinary clinics. This is an actual “first, do no harm” approach vs. assuming revaccination is safe “most of the time” and hoping for the best for each repeatedly injected animal.

Many canine companions today, especially seniors, have at least one chronic disorder or disease. To assume that because these dogs have no history of vaccine adverse reactions, they will derive more benefit than risk from repeated vaccinations against diseases they are very likely already immune to, makes absolutely no sense.

It makes much more sense, and is ultimately much more humane, to check their immune status through titer testing rather than subject their aging and/or compromised bodies to repeated rounds of potentially unnecessary, problematic chemical agents.

It’s worth nothing that passionate pet parents and proactive veterinarians in other parts of the world have developed much more progressive titering protocols that should also be the standard of care in North America.

In the Netherlands and Belgium, for instance, many veterinarians titer puppies and kittens before their first vaccines to determine if there are maternal antibodies present, and can predict when a puppy’s immune system is competent to receive vaccines by completing maternal nomographs. This allows animals to receive one perfectly timed vaccine, followed by a titer 4 weeks later to ensure they were adequately immunized.

Integrative vets in this country understand convincing clients to titer once after young animals have received their initial vaccines has taken many years to accomplish. Convincing owners to titer before and after a vaccine is absolutely the best medicine but may prove to be a difficult protocol to institute for economic reasons.

Let’s hope the demand for titer tests continues to increase among pet parents, along with access to affordable testing. Your vet can submit samples to University of Wisconsin-Madison vet school for a reasonable fee ($55) and Healthy Dog Workshop allows pet parents to submit their own samples.

If your own veterinarian isn’t offering titers at a reasonable cost, shop around. Any veterinarian truly concerned about the health of pets should happily offer affordable titer testing in lieu of automatic revaccination.

Titer tests can be run as often as a pet parent wishes (most vets suggest every 1-3 years) to ensure their dog or cat is still protected against disease, with the understanding that immunity against core diseases lasts much longer than current vaccination guidelines indicate — often for the animal’s lifetime. I don’t usually titer indoor housecats after their initial core vaccines because their exposure is effectively zero.

When it comes to rabies, I prefer to give the first vaccine at 6 months, and then as required by law, a booster 1 year later and every 3 years thereafter. Dr. John Robb’s Protect the Pets campaign is working to amend the mandatory rabies over-vaccination laws in each state, and to accept rabies titers instead.

“This is very simple stuff,” says Dr. Robb, who I’ve interviewed. “We vaccinate to produce immunity. We can measure that immunity with a simple blood test called the titer.”

I don’t typically recommend non-core vaccines. Each vaccine your pet receives should meet the following criteria:

  • First, your dog or cat should be healthy. If she has allergies, endocrine issues, organ dysfunction, cancer (or is a cancer survivor), epilepsy or another medical issue she’s not a candidate to receive vaccines.
  • The vaccine is for a life-threatening disease (this eliminates most non-cores immediately).
  • Your pet runs the risk of exposure to the disease.
  • The vaccine is considered both effective and safe (most aren't, especially the bacterins Lyme and Lepto).
  • Your pet has never had an adverse reaction to a vaccine. Do not vaccinate a pet that has had a previous vaccine reaction of any kind.

If you do vaccinate your pet, ask your integrative veterinarian to provide a homeopathic vaccine detox such as Thuja (a common choice for all vaccines except rabies).

It’s also important to realize that several non-core vaccines are only available in combination with other vaccines, some of which are core. I recommend you check with your vet to ensure none of the non-core vaccines are being piggybacked on core vaccines your pet receives.

Unfortunately, most conventional veterinarians do not carry single or even core-only vaccines, so it’s a good idea to ask to see the vaccine vial before assuming your pet is only receiving one agent at a time. You can find an integrative or wellness veterinarian who will customize a vaccine and titer protocol around your pet’s individualized needs here.

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