Long-term outcomes and prognostic factors in dogs with meningoencephalitis of unknown origin and suspected necrotic lesions on magnetic resonance imaging: 37 cases (2007-2020).

OBJECTIVE

To describe the long-term outcomes, overall survival, progression-free survival, and prognostic factors in dogs with necrotizing encephalitis (NE).

ANIMALS: 37 client-owned dogs clinically diagnosed with NE.

METHODS

All dogs underwent MRI and CSF analysis. Cox proportional hazards regression was used to examine factors related to the risk of relapse and death, including signalment, history, diagnostic investigation results, and treatments before the first relapse.

RESULTS

The medians of the overall and progression-free survival times were 639 days (IQR, 342 to 1,482 days) and 233 days (IQR, 111 to 775 days), respectively. Overall survival was highly correlated with progression-free survival. Four dogs (11%) died or were euthanized within 3 months of diagnosis. Relapse within 6 months was associated with a shorter overall survival. However, no prognostic factors for overall survival were found. The category of patients with presenting clinical signs that lasted 29 days to 6 months (OR, 3.26; 95% CI, 1.35 to 7.90) was associated with a higher risk of relapse. Seizures were presented in 75.7% of dogs, with a recurrence rate of 100%.

CLINICAL RELEVANCE: This report provides comprehensive follow-up information for dogs with NE, revealing a fair prognosis and low early mortality rate. Seizure is a very common clinical sign with a high recurrence rate.