A guide to safer vaccinations

veterinary care

Not so long ago, dogs received routine vaccinations every year, usually at their annual check-up, but things have changed dramatically in the last decade. Challenge studies and blood titre results show that modified live vaccines (MLV) protect animals for as long as seven years and possibly for life. This makes annual vaccination unnecessary for the vast majority of dogs and possibly even dangerous for others. So how do you ensure your dog is protected both from disease and overvaccination? The best strategy is to learn which vaccinations are absolutely necessary, when and why your dog needs them, and how to gauge when he has achieved lifelong immunity.

When should you vaccinate?

Dr. W. Jean Dodds, an Ontario Veterinary College – trained veterinarian and renowned researcher now living in California, conducted her own vaccine challenge studies a few years ago. She recommends a vaccination schedule that maximizes protection while minimizing risk. Her core vaccines include Distemper,Parvovirus and Rabies.

Note that she and many other veterinarians believe it’s much safer to give the Rabies Vaccine after 20 weeks of age, and always separately (three to four weeks) from other vaccines. While some veterinarians also include Canine Adenovirus-2 (CAV-2) as a core vaccine, Dr. Dodds feels the rarity of canine hepatitis (Adenovirus-1) and the immunosuppressive effect of the CAV-2 vaccine when added to Parvovirus and Distemper may outweigh the benefits of vaccinating.

Dr. Dodds cautions that some combo vaccines contain many more than the two or three vaccines your dog needs. The American Animal Hospital Association Canine Vaccine Task Force seems to concur, adding Giardia spp. (now off the market) and Canine Coronavirus (CCV) to the list of vaccines generally not recommended. Other vaccines, such as for Lyme disease, may be irrelevant since the disease usually affects only certain geographical areas.

Talk to your veterinarian about these and other optional vaccines such as Leptospirosis and Bordatella to see how prevalent they are in your region and what your dog’s individual risk factors might be.

Tip: According to Dr. Dodds, from an immunologic perspective, any killed vaccine, including those for Rabies Virus, should be adjusted according to the size of your dog, but “they usually aren’t” she says, “because the vaccine label doesn’t say this can be done”.

Dr. Dodds minimal vaccine schedule

Note: The following should not be interpreted to mean that other protocols recommended by a veterinarian would be less satisfactory. It’s a matter of professional judgement and choice.

Age of pups Vaccine type
9 – 10 weeks Distemper + Parvovirus, MLV (e.g. Nobivac DPV)
14 weeks Same as above
16 – 18 weeks (optional) Same as above (optional)
20 weeks or older, if allowable by law Rabies
1 year Distemper + Parvovirus, MLV (or a titre may be run instead)
1 year Rabies, killed 3-year product (give 3 – 4 weeks apart from distemper/parvovirus booster)

What are some of the adverse reactions to vaccination?

Adverse reactions to conventional vaccinations can happen immediately (hypersensitivity or anaphylactic reaction) or up to 45 days later in a delayed type immune response, according to Dr. Dodds. She says typical signs of adverse reactions include fever, stiffness, sore joints and abdominal tenderness, susceptibility to infections, central and peripheral nervous system disorders,
inflammation, jaundice or generalized pinpoint hemorrhages or bruises. Liver enzymes may be elevated and liver or kidney failure may accompany bone marrow suppression.

Furthermore, says Dr. Dodds, recent vaccination of genetically susceptible breeds has been associated with transient seizures in puppies and adult dogs, as well as a variety of autoimmune diseases including those affecting the blood, joints, skin, central nervous system, eyes, muscles, liver, kidneys, bowel and endocrine organs.

In particular, Dr. Dodds recommends a cautious vaccine schedule for Akitas, Weimaraners, Harlequin Great Danes, white-coated breeds and dilutes within breeds, Standard Poodles, Old English Sheepdogs, some families of American Cocker Spaniels and Vizslas.

Choose wisely

As your dog’s health care advocate, it’s up to you to determine the safest vaccine protocol that provides optimum protection. The more details you have, the more informed decisions you can make. So do a little research now – it may pay off down the road.

At the time of this writing, a privately-funded study called the Rabies Challenge Fund is underway to change current vaccination laws by proving that the duration of immunity for the Rabies Vaccine is much longer than conventionally believed. Spearheaded by Kris Christine, Dr. Dodds, and Dr. Ron Schultz of the University of Wisconsin School of Veterinary Medicine, the aim is to extend the required interval for Rabies boosters from three years to five, and then seven years. The five-year study results will be available later in 2013, and the 7-year trial is underway, thanks to donations from private citizens around the world. Find out more at rabieschallengefund.org.

Disease/vaccine Description Minimum duration of immunity (Based on challenge studies)
Canine Parvovirus (CPV-2) Very contagious; attacks intestinal tracts, causing vomiting, diarrhea, fever, dehydration and often death; mortality rates can reach 100% in pups under one year. Mortality figures drop dramatically as the dog matures. Minimum 7 years
Canine Distemper Virus (CDV) Attacks the respiratory, GI and central nervous systems; pups up to six months most susceptible.


Easily destroyed by outside influences such as water, disinfectant and sunlight.

5 – 7 years, and perhaps even longer. In fact, titers have indicated that dogs can be protected for nine to 15 years.
Rabies (RV) Infects central nervous system, causing encephalitis and death.


Unlike Distemper and Parvo, Rabies can be transmitted from animals to humans, which is why Rabies Vaccines are required by law throughout North America.

Min. 3 years or according to law, or medical certificates should be obtained for animals showing adverse reactions to the vaccine.



Canine Adenovirus-2 (CAV-2) Includes CAV-1 (canine hepatitis) and CAV-2, a respiratory infection. Sometimes considered a core vaccine but creates an immunosuppressive effect in puppies since it is available only in a combination vaccine with parvovirus and distemper.


May consider it at over one year of age if available as a single dose.

Minimum 7 years
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Dana Cox is the co-founder, Chief Creative Officer and editor-in-chief of Redstone Media Group, which publishes Canadian Dogs Annual, Animal Wellness Magazine, Equine Wellness Magazine and Integrative Veterinary Care Journal, and associated websites. She regularly attends veterinary conferences to stay apprised of leading edge and best practice therapies and modalities. Dana lives in Peterborough, ON with her husband and fellow co-founder, Tim Hockley, and their family which includes two children, a dog and a cat.