# Combination of azathioprine and prednisolone as a treatment for meningoencephalomyelitis of unknown origin in dogs: 54 cases

## TL;DR

A combination of azathioprine and prednisolone can lead to long survival times in dogs with meningoencephalomyelitis of unknown origin, though some cases experience serious side effects.

## Contribution

This study reports on the long-term outcomes and tolerability of a specific drug combination for treating MUO in dogs.

## Key findings

- Median survival time was 1289 days for dogs treated with azathioprine and prednisolone.
- Adverse effects like myelosuppression and hepatotoxicity occurred but were reversible in most cases.
- No significant difference in survival time was found between dogs with or without seizures or relapses.

## Abstract

Information regarding efficacy of combination of azathioprine and prednisolone in treating meningoencephalomyelitis of unknown origin (MUO) in dogs is limited.

To report median survival time in dogs with MUO treated with a combination of azathioprine and prednisolone and assess its tolerability.

Ninety-two dogs diagnosed with MUO between January 2011 and December 2022 that received azathioprine and prednisolone.

A retrospective medical record review was conducted. Diagnosis of MUO was based on clinical signs, magnetic resonance imaging features, and cerebrospinal fluid analysis.

Median survival time was 1289 days (range: 30-3356). Median survival time did not differ significantly between dogs that presented with seizures (n = 12; 308 days) and those without seizures (1289 days; P = .74), nor between dogs that experienced relapses (n = 20; 1153 days) and those that did not (1697 days; P = .58). Myelosuppression occurred in 10 dogs and hepatotoxicity in 1 dog. In 9 dogs, adverse effects resolved with drug discontinuation or dose reduction. One dog died from hepatic necrosis and 1 from myelosuppression.

Combination of azathioprine and prednisolone is associated with long median survival times for dogs with MUO in this study. Adverse drug reactions were reversible in most cases but can be fatal in some. Therefore, hematological values and hepatic variables should be monitored.