The Dose Makes the Poison in Pet Vaccines

The Dose Makes the Poison in Pet Vaccines

Story Highlights

  • Almost all states in the U.S. require certain core vaccines for companion animals including dogs, cats and ferrets, with many expected to be repeated annually.
  • Vaccine dosages are given on a one-size-fits-all basis, so that Chihuahua puppies and full grown Mastiffs receive the same amount of vaccine.
  • Despite data showing that small breeds are more likely to experience adverse reaction to vaccines, research is sparse and one-size-fits-all pet vaccination laws have not changed.

As is the case with vaccination mandates in humans, laws vary by state regarding vaccines required for pets. A few states do not require any vaccines at all, but most states highly recommend several annual vaccines, and all but eight states have laws requiring repeated rabies vaccination for dogs, cats and usually ferrets.1 Rabies vaccination is most commonly required within the first few months of the animal’s life and then either annually or every three years thereafter (fun fact: the one-year and three-year vaccination products are identical except for labeling2).

Citing studies from the top animal vaccine manufacturers in the United States, veterinary immunologist Dr. Ronald Schultz reported that all studies found that core canine vaccines (canine distemper virus, canine parvovirus type 2 and canine adenovirus) sustained their duration of vaccine acquired immunity (DOI) for at least three years and that feline core vaccines (feline parvovirus, calicivirus and herpes virus type I)3 had a DOI of more than three years and did not need to be repeated annually. Many other studies concur that vaccine-induced antibodies are sustained far beyond one year and that annual re-vaccination is unnecessary.4

Vaccines Disregard Size Differences

When human children are vaccinated, they receive the same vaccine dosage regardless of the child’s size, so both the 20-lb one-year-old and the 50-lb six-year-old would receive the same 0.5 mL dose of the MMR (measles, mumps, rubella) vaccine. Even more dramatically, the same rule holds true for the 5-oz Chihuahua puppy and the 200-pound adult Mastiff, or the tiny kitten and the adult lion: same dosage of vaccine, with many of them repeated annually. 

The supposed rationale for indiscriminate use of vaccines is the same regardless of species: Vaccines are considered safe, even for preterm or very low weight babies5 (or puppies or kittens) and most vaccine testing is done simply to determine the “lowest effective dose for the target age group.” The explanation offered is that vaccines do not work like drugs, which have a greater effect when concentrated in a smaller body and, therefore, dosage must be adjusted for body weight. Instead, the reasoning goes, vaccines act more like an “on/off switch” to educate injection site immune cells that then circulate throughout the body.6

However, it has also been reported that, “Vaccine developers must practice good medicine and good economics. Giving larger doses of active ingredients than required would increase the side effects from and the costs of vaccines.”7

Isn’t a one-size-fits-all dosage the equivalent of giving a “larger dose of active ingredients” when injected into a baby’s tiny body?

Pet Size Matters in Vaccine Safety

Numerous studies have shown that adverse reactions to vaccines are not uncommon among dogs and range from milder effects such as fever, stiffness, sore joints, abdominal tenderness and behavioral changes to increasingly serious conditions including auto-immune disorders and rabies vaccine-induced development of anti-thyroglobulin autoantibodies implicated in the onset of hypothyroidism. Vaccines have also been linked with an increased susceptibility to infections, cancer, neurologic disorders and encephalitis, as well as with jaundice, organ failure and collapse with auto-agglutinated red blood cells.8   

It has also been shown that adverse effects are far more prevalent in small dogs than in larger breeds. In a search of electronic records from 1,226,159 dogs vaccinated at 360 veterinary hospitals, it was determined that not only was the risk for vaccine associated adverse events (VAAE) inversely proportionate to size of the dog, but risk also was “27% to 38% greater for neutered versus sexually intact dogs and 35% to 64% greater for dogs approximately 1 to 3 years old versus 2 to 9 months old.”

The researchers also found that adverse events “significantly increased as the number of vaccine doses administered per office visit increased; each additional vaccine significantly increased risk of an adverse event by 27% in dogs ≤ 10 kg (22 lb) and 12% in dogs > 10 kg.”

It is important to note that in that study, the researchers focused on a very few specific adverse events. They did not report reactions that occurred more than 72 hours after vaccination (so left out reactions such as injection site sarcomas and autoimmune diseases that developed later) or reactions that had not been selected for evaluation, such as seizures or many other common vaccine reactions. They also omitted reactions not reported on time by pet owners and reactions not recognized at the time by veterinarians.9

The authors concluded that, “Young adult small-breed neutered dogs that received multiple vaccines per office visit were at greatest risk of a VAAE within 72 hours after vaccination.10 

Dr. Jean Dodds, a well-respected authority on pet vaccines, identified several other factors that may increase the risk for vaccine reactions. Specific breeds, for example, appear to be at increased risk and include Akita, American Cocker Spaniel, Dachshund, German Shepherd, Golden Retriever, Great Dane, Irish Setter, Kerry Blue Terrier, Old English Sheepdog, poodle (all types but especially the Standard Poodle), Rottweiler, Scottish Terrier, Shetland Sheepdog, Shih Tzu, Vizsla and Weimaraner.11 Other conditions that increase risk include all- or predominantly white fur and animals with “diluted” coloring, as in blue and fawn Doberman Pinscherss or Harlequin Great Danes. 

More Vaccine Research Needed

Vaccine research generally requires only that a vaccine can be shown to elicit an effect in the breed for which it is intended, so the relatively few animals involved in preclinical testing tend to be of “average” size.12 Recognizing that small breeds would be underrepresented in such studies, Dr. Dodds conducted a small pilot study to evaluate the immunologic effectiveness of giving a half dose of distemper and parvovirus vaccines to dogs weighing less than 12 pounds.

The study set out to document what had been apparent over more than 50 years of clinical and research experience, namely, that a half dose of certain vaccines does provide adequate titer levels (a titer test is a measures the blood for the presence of specific antibodies, whether to vaccine or natural exposure to an infectious agents).13

The 13 small dogs in the study were all between three and nine years of age, had not been given any routine vaccinations for at least three years, and weighed less than 12 pounds. Four-week and six-month titer testing showed sustained antibody levels to both the canine distemper and parvovirus diseases, compared to the pre-vaccination levels. The researchers concluded that the half doses were effective in the small study group, and that the concept merited further study in a larger population. 

Three years later, although many references cite this small pilot study, no follow up has been done and one-size-fits-all pet vaccination laws have not been changed to reflect the greater risk of vaccine adverse reactions in small breed pets.


1 State Rabies Vaccination Laws for Domestic Dogs, Cats, and Ferrets in the United States. The Policy Surveillance Program Mar. 9, 2019.
2 Campbell Thornton K. AVMA 2017: Rabies Vaccination – What You Need to Know. American Veterinarian July 25, 2017.
3 Schultz RD. Duration Of Immunity For Canine And Feline Vaccines: A Review. Science Direct Oct. 2006.
4 Brady C. So Humans Need to be Vaccinated for Viruses as Babies and That Lasts for Life but Dog Vaccinations Need to be Given Every Year?! 
Immunizations For Preterm Babies. Aug. 23, 2017.
What’s the Right “Dose” of a Vaccine for Small-Breed Dogs? Jan. 18, 2016.
Vaccine Schedule: Other Schedule Issues. Children’s Hospital of Philadelphia Mar. 18, 2019.
Brady C. Dog Vaccinations Part 2: Side Effects. 
Rasmusen J. Vaccinating Small Dogs: Risks Vets Aren’t Revealing. Sept. 30, 2009.
10 Moore GE, et al. Adverse Events Diagnosed Within Three Days Of Vaccine Administration In Dogs. J Amer Vet Med Assoc Oct. 1, 2005. 
See Footnote 8.
Khuly K. Smaller Dog, Smaller Vaccine. The Daily Vet July 27, 2011.
Dodds WJ. A Pilot Study: 1/2 Dose Vaccines for Small Dogs. Hemopet Jan. 17, 2016.

15 Responses to "The Dose Makes the Poison in Pet Vaccines"

  1. Randall Tillotson   September 20, 2019 at 10:23 pm

    I’ve got a new corgi mix puppy. I’ve been weighing getting the little guy vaccinated. You can’t leave a pet in a kennel without having all the shots. I’m retired and don’t travel much, but I may have to leave him somewhere for some reason. Not sure what to do. I don’t want to harm him with vaccines. I’m a NVIC supporter, so I follow all the news on the adverse reactions. It’s a dilemma for sure.

    • Donna   September 21, 2019 at 8:52 am

      Yes, Randall, it is indeed a dilemma for us dog owners too! I don’t travel and so far haven’t had to leave my dog at the vet clinic which would require ALL their vaccines if I left my dog(s) there. I have a vet who let’s me drop off my dog for dental work and pick her up as soon as she wakes up so she isn’t left there to stay in their kennel, like some people who might have to leave the dog until late afternoon. If you travel sometimes, do you have any reliable pet sitters in your or a reliable friend/relative? I follow Dr. Jean Dodds, Dr. Will Falconer, and Dr. Karen Becker for support and comfort! ? Because I had a Chihuahua years ago who had seizures after vaccines, I know how scary that can be for our smaller breeds.

    • CAWS   September 21, 2019 at 9:18 pm

      Check out trusted house sitters dot com. World wide site that allows you to have free pet sitting by folks who will come stay with your pet for free for the use of your house. You can also look for free housing by becoming a pet sitter. We have done it in SC ,AZ, and DC and saved hundreds of dollars every time. Meet interesting people, pets and save money. Win Win!

    • Kim   September 23, 2019 at 4:32 pm

      Hi Randall,
      I appreciate your loyalty to your puppy regarding not vaccinating him. We are the same way. We had a Weim who lived to 13, and was never vaccinated. Wherever we went he went. If we wanted to go to a concert, either my husband and Daughter would attend, while I stayed at the hotel with our precious pup, or I and my Daughter would attend the concert while hubby stayed with him. When we went on vacations, we stayed at pet friendly cabins or hotels only. We did this because we didn’t want him harmed, maimed or killed by vaccines and we did not want to leave him at a kennel around other dogs who possibly had diseases FROM vaccines. It was a challenge at times, but would not trade all of that time for the world.

  2. Anne Craig   September 20, 2019 at 11:31 pm

    Hire a reputable pet sitter. I would not board my dog because you must over-dose them with vaccines to leave them there. There are organizations of professional sitters.

  3. Aly   September 21, 2019 at 1:33 am

    My chi mix who is 10 lbs had severe reactions after her vaccinations. She couldn’t move, cried and shook for 3 days after her vaccinations. The vet said that this was normal and not to worry! He gave her pain meds and didn’t put in her chart that she had a reaction. I know this because the vet retired and sold his clinic to a new vet that wants me to give my dog more vaccines and I told him I don’t like how my dog has responded to the vaccines and he said that there is nothing in her chart that says she had a reaction. It’s unbelievable, frustrating and sad.

  4. Marlies   September 21, 2019 at 1:48 am

    You can get a pet sitter that comes to your home.
    I have a dog with Addison’s and a lump on her side that I will find out on Monday if it’s cancerous.
    It’s very hard to have an unhealthy pet. I cook her organic dinners and now started on an anti cancer diet.
    Next pet I want has to be totally natural no vaccines and organic food only.

  5. Caws   September 21, 2019 at 8:32 am

    The only thing that makes no sense here is the statement that adverse reactions were 35-64% more common in dogs 1-3 years old than puppies 2-9 months old. If size matters was that a typo? I’m also betting the figures on spayed & neutered pets being higher is because new or stray pets are often given all their shots at the same time they are fixed along with a dose of wormer and heart worm medicine. Poisons all around all at once!
    I am 67 years old and have only ever seen distemper in a litter once and they were underfed, overhandled [stressed] & kept in filthy conditions.Unfortunately it is no longer possible to get distemper alone; only the 4-5 way shots are available.
    I have lost 2 dogs to vaccine reactions. One super healthy lab to nasal bordatella/pertussis which is a live virus [as opposed to the shot which at the time was not] and the vet had been instructed not to give the nasal one as dog had also had a bad reaction to parvo vaccine as well but he was in kennel while I was on vacation. The other was stray JR terrier that was given the full size 5 way & rabies and not tested before hand for Parvo as I had requested. She immediately became desperately ill vomiting & diarrhea . They took her in the back and said we’ll keep her overnight she’ll be fine . $750 later they said she must have had Parvo beforehand and MIGHT survive with a blood transfusion [another $1000] but no guarantee. This was a stray! I was furious and told them to put her out of her misery.
    Vet said he called the manufacturer and they said not possible to contract Parvo from the shot. THAT IS A BIG FAT LIE! My research unearthed a study paid for by two wealthy breeders who lost whole litters of expensive puppies after spending thousands to try to save them. They hired an independent virologist and he determined that the Parvo virus that killed them was vaccine derived [lab created strain] NOT WILD VIRUS!
    Then when I realized my vet was conducting a study of hair samples from pets to determine levels of aluminum levels accumulating & causing problems, I realized something was up. Turns out that since cats were consistently getting sarcomas AT THE INJECTION SITES the vaccine companies had decided to switch all vaccines from dead strains of virus to attenuated LIVE viruses, INCLUDING RABIES! Now I only get the minimum required by the state [one rabies shot every 3 years] and avoid the vet unless I have an emergency. There are Homeopathic NOSODES that can be purchased for every disease that will produce protection & show “antibodies” on a titer test. I truly believe that the over vaccination of our pets [and the toxins in their foods] is causing the burgeoning levels of diabetes, epilepsy,kidney failure, arthritis& cancer in younger & younger animals.

  6. rachel   September 21, 2019 at 4:57 pm

    I had three doggies, the town I lived in threatens dog ‘owners’ that if their dog is not licensed they can receive a large fine. I do NOT believe in vaccines for humans, or doggies, but because of the threat of fines I got them vaccinated. Every year of course the town got paid for three dog licenses, and the vet regularly would unfortunately re- vaccinate them, which I hated. did not want to and would never do it again. As a vegan I fed them a raw healthy diet with raw meats. Vaccines and their caustic ingredients do not fit into a healthy lifestyle.
    Many dogs now have problems with seizures. My guess is they either are directly caused by vaccines and/or the poor quality of the animal carcasses they are fed (who themselves receive drugs, antibiotics, GMO foods and so on). Thank you for sharing information.

  7. Joi de Vivre   September 21, 2019 at 8:16 pm

    Little known is the fact that vaccine doses are 10x that required for a Great Dane. Why? Because the vaccine might lose potency from sitting on a shelf.

    Another little item of interest is that it is recognized that cats often have tumors forming at injection sites, usually the hind leg. Rather than stop vaccinating, the AVMA has suggested vaccinating in the tail because it’s more easily removed.

    I stopped vaccinating my animals years ago. When asked if they are “up to date”, I answer “yes”. lf asked for their papers, I say, “I forgot to bring them. I’ll have them next time.”

  8. Lin Ray   September 22, 2019 at 8:22 am

    We have always had dogs and have never boarded them. Over the years more and more hotels are becoming pet friendly making travel a lot easier and the rooms are becoming nicer each time we stay somewhere. Both my current elderly Cavs have breed related heart issues and the only vaccine they get is rabies but I delay 18-24 months past due date. No one has ever asked me for vaccine records. When we have needed a pet sitter such as for my son’s graduation in another state there is usually a young person working at the complex willing to make a couple extra dollars to watch tv and keep them company in the room or apt. Camping is also an excellent way to travel with pets without leaving them alone. Look for restaurants with outdoor seating which may be more agreeable to bringing Fido onto, or just order carry out and find a nearby park to eat at and take in the scenery. My vets have always been very agreeable both in FL and IL in allowing me to choose what vaccines, if any, they receive. You never know a vet’s reaction to going off vaccine protocol unless you ask.

  9. Ellie   September 23, 2019 at 10:04 pm

    Randall Tillotson, I’ll care for your corgi if you ever have to travel! Don’t vaccinate the little guy!

  10. ellie   September 23, 2019 at 10:10 pm

    Highly recommended: 7-par docu-series – The Truth About Pet Cancer by Ty Bollinger and team:

  11. George   December 25, 2019 at 11:24 am

    I have owned two dogs that were damaged from the rabies vaccine. The first one, a Bichon Frise developed AIHA (hemolytic anemia) shortly after receiving a rabies booster at age 9. It cost me over $12,000.00 to keep him alive until he died at age 16. He needed several hospitalizations with transfusions initially and gradually seemed to grow out of the disease. Of course he was put on prednisone until that stopped working then switched to an immune suppressant which seemed to work for him. Luckily he never developed cancer and died from congestive heart failure. My second dog, whom is still with me, is an affinpinscher, another small breed. He was perfectly healthy until he got a rabies shot also at age 9. This caused him to become hypothyroid shortly thereafter. He now takes thyroxin daily. The bottom line here is that rabies vaccines are DEADLY for dogs and they keep the vets very wealthy having to treat all the auto immune disorders they cause.

  12. Laura Dorman   May 18, 2022 at 12:28 am

    I have to say that I am very upset at reading that all dog vaccines are now using live viruses. Before COVID-19 hit, i was very diligent in getting my dog vaccinated on time. But not anymore. She’s a Boston Terrier and she came down with a nasty skin disease which I think was demodectic mange because her immune system had been depressed by the vaccines she’d received before she got the mange. So now if I refuse the rabies vaccine, I will be breaking the law! This puts me and my dog, who is like a child to me, in a really bad dilemma! Thanks for the information. I like my vet. But he’s very allopathic and I am going to have to talk to him alone and just demand titres.


Leave a Reply

Your email address will not be published.