Background: Vaccination and seasonality are inconsistently reported risk factors for auto-immune diseases in dogs and humans. Prospective studies evaluating these risks in a large number of dogs with meningoencephalitis of unknown origin (MUO) and steroid-responsive meningitis-arteritis (SRMA) are lacking.
Objectives: To prospectively evaluate the association between vaccination and season and development of new-onset MUO or SRMA. Animals: 191 client-owned dogs diagnosed with MUO (n=172) or SRMA (n=19) at a single private practice between August 2021 and July 2023.
Methods: Dogs were enrolled after meeting established diagnostic criteria for MUO or SRMA. Signalment, body weight, vaccination history, and season of onset of neurologic signs were recorded. Vaccination window was divided into 45-day time intervals and statistically compared for MUO and SRMA (total and individually). Season of onset (winter, spring, summer, fall) was also compared.
Results: 50 (26.2%) dogs received no vaccinations in the previous year. Of the 141 dogs vaccinated in the previous year, more (24.8%) received vaccine(s) in the 45 days preceding clinical signs compared to any other 45-day interval in the preceding year (P = .083). Vaccines administered most frequently included Distemper/Adenovirus/Parvovirus/Parainfluenza (25.7%), Bordetella (17.1%), and Leptospira (17.1%). There was no statistical difference between MUO and SRMA when evaluated separately. Cases were slightly more common in the spring (28.8%) and least common in the summer (19.9%)(P = .635). Conclusions and Clinical Importance: This study demonstrated no overall statistical risk for development of MUO/SRMA post vaccination; the preceding 45 days was the highest risk window in vaccinated dogs. There was no seasonal risk for MUO or SRMA.
