An assembly includes a rectilinear rail that has a backside connected to a side wall of the pet house. The rail is registered along a horizontal plane and elevated from a ground surface and has a chamfered top wall provided with a linear groove extending along a length of the rail. The groove is laterally offset away from the back side and proximate to a near side of the rail. Coextensively shaped trays are slidably positional along the rail. The trays include monolithically formed fingers extending away from a center thereof that are intercalated within the groove. Each tray includes a spring-actuated mechanism for maintaining a predetermined tension between the fingers and an inner surface of the groove such that the trays are prohibited from displacing along the groove. The spring-actuated mechanism is permanently affixed to each of the trays.