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.” Read more »