or MRI will show patchy, diffuse, or multifocal lesions. For a number of years, the basic treatment was some type of corticosteroid in combination with one or more immunosuppressive drugs, typically cytosine arabinoside and/or cyclosporine or other medications such as azathioprine, cyclophosphamide, or procarbazine, of which were usually added one at a time to the corticosteroid until a successful combination was found. There is evidence that treatment with radiation therapy for focal GME provides the longest periods of remission. Pug dog encephalitis Pug dog encephalitis (PDE) is an idiopathic inflammatory disease primarily affecting the prosencephalon (forebrain and thalamus). It is also known as necrotizing meningoencephalitis. The disease may be inherited in Pugs and Maltese and has been diagnosed in other breeds as well (Yorkies, Chihuahuas). The prevalence of PDE in pugs is about 1%. It differs in pathology from GME by more tissue breakdown and increased eosinophils (white blood cells). CSF analysis is also unique among inflammatory CNS diseases in dogs in that the cells are predominantly lymphocytes, instead of a mixed population of mononuclear cells. In Maltese and Pugs, there is extensive necrosis and inflammation of the gray matter of the cerebrum and subcortical white matter. The most common early symptoms are related to forebrain disease and include seizures and dementia, and later circling, head tilt, and blindness with normal pupillary light reflexes may be seen. PDE has a poor prognosis. Necrotizing leukoencephalitis In Yorkshire Terriers there can be severe mononuclear inflammation of the brainstem and periventricular cerebral white matter. Because the condition in this breed frequently affects only the white matter, it has been called necrotizing leukoencephalitis. Symptoms of brainstem and central vestibular disease predominate. Other types of noninfectious meningoencephalitis Steroid-responsive meningoencephalitis is any noninfectious meningoencephalitis that responds well to corticosteroids and usually has an excellent prognosis. This could represent mild forms of GME or PDE, but there are two separate conditions recognized also. Steroid-responsive meningitis/arteritis, also known as necrotizing vasculitis, is seen most commonly in Beagles, Boxers, Bernese Mountain Dogs, and German Shorthaired Pointers younger than two years of age. Many cases have fever, loss of appetite, and severe neck pain without other neurologic symptoms, although long-term cases may have incoordination and limb weakness or paralysis. CSF analysis shows predominantly neutrophils. In Beagles this condition is also known as Beagle pain syndrome. Eosinophilic meningoencephalomyelitis is seen mainly in Golden Retrievers. CSF analysis shows predominantly eosinophils. An acute