"Pseudomys shortridgei" is in a critical weight range of small to medium mammals that succumbed to a mass extinction event during the period 1875 to 1925, the result of one or several threatening factors that caused localised, near or complete extinction.A theory that proposes the primary cause as an epizootic, a novel disease that spread from the Western Australian coast, may be the cause of its apparently large population decline or disappearance; in modelling of the hypothetical disease this species was estimated to have had weak immunity that accounted for its large reduction in range.