N05 - Survival in Dogs with Meningoencephalomyelitis of Unknown Etiology with and without Magnetic Resonance Imaging Lesions

Background: The prognosis of dogs with meningoencephalomyelitis of unknown etiology (MUE) is difficult to predict. MUE cases with normal magnetic resonance imaging (MRI) occur, but it is unknown whether this finding alters prognosis.


Hypothesis: Normal-MRI MUE dogs survive longer than MUE dogs with MRI lesions.

Animals: 82 client-owned dogs with MUE presenting to a university hospital from 2010-2020.


Methods: Retrospective study. Dogs with a clinical diagnosis of MUE were included if they were between 6 months to 10 years at diagnosis, had brain or spine MRI performed, had a CSF white blood cell count > 5 cells/uL, were tested for infectious diseases, and had follow-up for ≥ 3 months or until death. MRIs were reviewed for the presence or absence of MUE lesions. Deaths due to MUE were compared between dogs with and without MRI lesions using a Kaplan-Meier curve. A log-rank test was performed to evaluate statistical significance (p < 0.05).


Results: Sixty dogs (73%) had MRI lesions with a median survival of > 70.7 months. Twenty-two dogs (27%) did not have MRI lesions with a median survival of > 98.0 months. The death rate was 23% for dogs with MRI lesions and 9% for dogs without (p = 0.152).


Conclusions: The majority of MUE dogs had prolonged survival. No statistically significant difference in death rate of dogs with and without MRI lesions was found. Additional outcome measures (e.g. remission rates) with extended follow-up should be studied to determine whether the presence of MRI lesions influences prognosis in MUE.