Necrotizing meningoencephalitis

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Necrotizing meningoencephalitis (NME) is a fatal brain disease in dogs. It mostly affects small breeds like pugs and is usually seen in dogs from about six months to seven years old. The disease causes severe inflammation that damages brain tissue, especially in the brain stem and cerebellum.

The exact cause is unknown. It is thought to be multifactorial and autoimmune, possibly with a genetic component. It is not contagious. The disease progresses quickly and often leads to seizures and death.

Diagnosing NME while the dog is alive is difficult. Vets may use MRI or CT scans, analyze the cerebrospinal fluid, and perform immune tests, but a definitive diagnosis is usually made only after examining brain tissue (through biopsy or after death).

What the brain looks like: there is inflammation of the meninges (the membranes around the brain) and the brain itself without pus. There are areas of tissue death (necrosis) mainly in the white matter of the brain, including the corona radiata, thalamus, and cortex. The meninges may be thickened with immune cells. In some cases, parts of the brain can push downward (cerebellar herniation), contributing to severe symptoms like circling or seizures.

Viral causes have not been proven. Treatments use immunosuppressive drugs (to calm the immune system) and anticonvulsants to control seizures, but these do not cure the disease. Some dogs live for several months with treatment, but the disease remains fatal, and euthanasia is often chosen.