ID08 - Risk Factors for Acute Adverse Events in Dogs Following Vaccination

Abstract: Background – Immediate-type hypersensitivity reactions and other acute adverse events have been documented in dogs following vaccination. Risk factors have been investigated >15 years ago, but changes in vaccines or shifting genetic profiles may have altered risk factors.



Objectives – Determine incidence rates and potential risk factors for adverse events (AEs) recorded within 3 days of vaccine administration in dogs



Animals – 4,954,565 dogs vaccinated at 21,103,149 office visits at Banfield Pet Hospitals.



Methods – Electronic medical records from 2016-2020 were used in a retrospective cohort study identifying all dogs receiving vaccinations and documenting potential vaccine-associated AEs within 3 days following vaccination. Incidence rates for AEs with 95% CIs were calculated, and associations for potential risk factors were assessed by logistic regression.



Results – The overall documented AE rate was 0.001845 (0.1845%, or 18.45 AE/10,000 dogs), or < 1/500. The 5 breeds (n >10,000) with highest AE rates were Dachshund, Boston terrier, miniature Pinscher, French Bulldog, and Havanese (68.62, 63.28, 53.73, 49.28, and 35.82 AE per 10,000, respectively). Increasing the number of vaccines administered increased AE risk in dogs ≤ 20kg (OR 1.23; 95%CI: 1.22-1.24) but not in dogs >20kg (OR 1.01; 95% CI: 0.99-1.02). AE rates for DAPP, leptospirosis, rabies, or Borrelia vaccines administered alone were similar (19.22-21.31 AE/10,000).



Conclusions and clinical importance – Small dogs receiving multiple vaccines per office visit remain at increased risk of AEs following vaccination, but AE rate by breed suggests genetics may be the greater risk factor for an acute AE.