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The Dogs Most Likely to Suffer a Vaccine Adverse Event

Analyzing the records of over 4.6 million dogs at more than 1,000 veterinary clinics shows a clear trend as to which dogs are more likely to react within three days of receiving a shot. Find out more about how vaccines can induce vaccinosis - a condition that some vets won't acknowledge.

vaccine adverse events in dogs


  • A recent 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
  • The study researchers looked at the records of over 4.6 million dogs over a 5-year period, and concluded that small dogs, those of certain breeds, spayed females, dogs around 1 year of age, and those receiving multiple vaccines in a single visit are at highest risk for vaccine adverse events within three days of administration
  • The study also concluded the rabies vaccine results in the highest number of moderate to severe adverse events
  • Vaccinosis differs from the acute, often immediate adverse reactions to a vaccine that were the subject of the study; the condition is recognized primarily by holistic and integrative veterinarians as 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
  • Fortunately, there is much you can do as your pet's primary advocate to ensure your dog's risk of adverse vaccine reactions is minimal

A recent study published by veterinary researchers from the College of Veterinary Medicine at Purdue University and Banfield Pet Hospital concludes that when it comes to vaccine adverse events (AEs) in dogs, the risk is increased in certain breeds, smaller dogs, and those receiving multiple simultaneous injections.1

Dogs Most Likely to Suffer a Post-Vaccine Adverse Event

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 (presumably 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

Vaccine Adverse Events Within 3 Days 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):2

  • 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."3

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 irritants4 (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

How to Protect Your Pet 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.

Subsequent 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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