Peer-reviewed veterinary case report
Vaccination and season risks for brain inflammation in dogs
By Johnson, Maria K et al.·Published in Journal of veterinary internal medicine·2025·Wheat Ridge Animal Hospital, United States·View original on PubMed →
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Original publication title: Vaccination and Seasonality as Risk Factors for Development of Meningoencephalitis of Unknown Origin in 172 Dogs.
- Species:
- dog
Plain-English summary
A group of 172 dogs diagnosed with meningoencephalitis of unknown origin (MUO), a serious brain inflammation, was studied to see if vaccination and the time of year affected the risk of developing this condition. The findings suggested that dogs were most at risk for MUO in the first 45 days after vaccination, with a significant drop in risk as time passed. While spring showed a slightly higher occurrence of MUO, the overall risk did not vary much by season. It's important for pet owners to be aware of this potential risk shortly after their dog is vaccinated and to monitor for any unusual neurological symptoms during that time.
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Abstract
BACKGROUND: Meningoencephalitis of unknown origin (MUO) is a neuroinflammatory disease that is suspected to be immune-mediated. Vaccination and season inconsistently have been reported as risk factors for development of MUO in dogs, but limited prospectively collected data is available to evaluate these potential risk factors. OBJECTIVE: Prospectively evaluate the association between vaccination and season and the development of MUO in dogs. ANIMALS: A total of 172 client-owned dogs diagnosed with MUO. METHODS: Dogs were enrolled prospectively from August 2021 through July 2023. Signalment, body weight, vaccination history, and season of onset of neurologic signs were recorded. The incidence rate ratio (IRR) of MUO within various post-vaccination windows was statistically compared to a referent window of 451-560 days post-vaccination. The incidence rate (IR) of MUO in each season was compared statistically. RESULTS: Of dogs vaccinated within the previous 450 days, MUO IRR was highest in the first 0-45 days (IRR = 9.14; confidence interval [CI] = 4.04-20.71), followed by 46-90 days (IRR = 4.86; CI = 2.01-11.71) and 91-180 days (IRR = 4.86; CI = 2.15-10.96) post-vaccination compared to the 451-560 day post-vaccination referent window. The MUO IR was slightly more common in the spring (28.5%) and least common in the summer (19.8%). No significant difference in IR between seasons was identified. CONCLUSIONS AND CLINICAL IMPORTANCE: In dogs with potential vaccine-associated MUO, the highest risk to develop MUO may be in the first 45 days post-vaccination. A slowly developing immune response to vaccination over 3-6 months may occur in some dogs. There is no apparent association between season and the development of MUO.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/40035184/