Vaccinating Cats and Small Dogs: A Special Danger

June 10, 2012

A Purdue University vet school study (by Moore et al), published in 2005 in the AVMA Journal and widely-cited elsewhere (see AAHA Guidelines p. 22), tracked vaccine reactions occurring within 72 hours of vaccination for 1.2 million dogs vaccinated at 360 veterinary hospitals. It showed that small breed dogs receiving multiple vaccines per office visit were at greatest risk of a vaccine reaction. The report recommends: These factors should be considered in risk assessment and risk communication with clients regarding vaccination.

“The VAAE [reaction] rate decreased significantly as body weight increased. Risk 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 risk of a VAAE 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.”  (Find the article: JAVMA, Vol 227, No. 7, October 1, 2005) Ask your vet to find the article at 

Note too: In the WSASA Guidelines Q & A: Are certain vaccines or combinations of vaccines more likely to cause adverse reactions than others? Yes. Although the development of an adverse reaction is often dependent on the genetics of the animal (e.g. small breed dogs or families of dogs), certain vaccines have a higher likelihood of producing adverse reactions, especially reactions caused by Type I hypersensitivity. For example, bacterins (killed bacterial vaccines), such as Leptospira, Bordetella, Borrelia (Lyme) and Chlamydophila (Chlamydia) are more likely to cause these adverse reactions than MLV viral vaccines.

Breeds Most at Risk Listed in Order (for breeds with more than 5000 dogs studied)

Dachshund  (by far the most reactive)
Boston Terrier 
Miniature Pinscher
Miniature Schnauzer 
Jack Russell Terrier 
Toy Poodle 
Shih Tzu 
English Bulldog 
Lhasa Apso
Bichon Frise 
American Eskimo Dog 
American Cocker Spaniel
Shetland Sheepdog 
Shar Pei 
Miniature Poodle
Golden Retriever 
Basset Hound 
Welsh Corgi 
Siberian Husky
Great Dane 
West Highland White Terrier
Labrador Retriever 
Doberman Pinscher 
American Pit Bull Terrier 
Australian Shepherd 
Australian Cattle Dog
Border Collie
Chow Chow
German Shepherd Dog

Read the study abstract for dogs.

Read the study abstract for cats: Adverse events after vaccine administration in cats: 2,560 cases (2002-2005).

CONCLUSIONS AND CLINICAL RELEVANCE: Although overall VAAE rates were low, young adult neutered cats that received multiple vaccines per office visit were at the greatest risk of a VAAE within 30 days after vaccination. Veterinarians should incorporate these findings into risk communications and limit the number of vaccinations administered concurrently to cats.  

Articles of Interest

Vaccinating Small Dogs: Risks Vets Aren’t Revealing          

Short video and article on vaccine reactions

Study about  increased hospitalization and deaths in children receiving multiple vaccines 




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2 Responses to Vaccinating Cats and Small Dogs: A Special Danger

  1. mindy lee on August 6, 2014 at 1:33 pm

    it is good to know that the multiple vaccines per office visit were at greatest risk for small dogs

    we experienced our yogi 6 lbs got sick each time after coming back from the vet for the vaccines.


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