An inflammatory brain disease specific to the Pug, formerly known as Pug dog encephalitis (PDE) and later renamed necrotizing meningoencephalitis (NME). It is an immune process, with lymphoplasmacytic infiltration, parenchymal necrosis and bilateral lesions predominantly in the brain. It produces progressive central neurological signs in the young adult, with a poor prognosis. The breed predisposition suggests a genetic basis, partly associated with the canine major histocompatibility complex (DLA).

NME multifactorial without a causal variant: OMIA classifies it as non-monogenic. A susceptibility test exists (DLA-II region and marker CFA12:2605517delC) that informs of risk, not of diagnosis; described mainly in the Pug and other toy breeds.

- Seizures appearing in the young adult
- Behavioral changes and disorientation
- Ataxia, blindness, proprioceptive deficits
- Headache/pressure and signs of intracranial pressure depending on location
- Progressive course, often with rapid deterioration over months

Pug encephalitis was described as an entity of its own in the late 70s and in the 80s when a pattern of recurrent necrotizing meningoencephalitis was recognized in the breed. It was later reclassified as NME within the group of non-infectious meningoencephalitides of the dog (along with granulomatous meningoencephalitis, GME). Genetic studies showed association with DLA (canine MHC) haplotypes, supporting an immunogenetic predisposition. No single causal mutation outside the DLA complex has been identified.

- When a case is confirmed in a line, do not repeat the parental cross
- Avoid breeding with affected animals or those with a close family history of NME/PDE
- Consider the risk DLA haplotype test (if available) in affected lines
- Given the multifactorial nature, it is not appropriate to select solely on the haplotype without weighing the rest of the health and genealogical context
- Communicate the history to the buyer of offspring from affected lines

Differential diagnosis with the other non-infectious meningoencephalitides (GME, necrotizing leukoencephalitis of small breeds) and with infectious (distemper, protozoa, rickettsiae) and neoplastic (lymphoma/reticulosis) encephalitides. Cranial MRI with bilateral lesions and CSF with lymphocytic pleocytosis guide the diagnosis; definitive confirmation is histopathological. Immunosuppressive treatment (glucocorticoids, cytostatics) with partial response and guarded prognosis. The immunogenetic predisposition supports the role of the DLA system in the disease.

Greer et al. 2010 (PMID 20403140); Barber et al. 2011 (PMID 21846746); van Renen et al. 2024 (PMID 38840637); OMIA:001470-9615 (multifactorial, sin variante causal conocida).