This bag is exactly what you were looking for--a Messenger Bag with structure to protect your pet in a crowd!  Keep the top open for walks around town, or pull the mesh drawstring cover shut to be approved for travel on public transportation.

Pictured bag is black leather with white contrast stitching detail.  Interior is nylon-lined for easy cleaning.  Safety strap (to be connected to a harness only!) and 3 side pockets.

Dimensions:  15.5"L x 6"W x 8.5"H

Larger size and other fabric available (call for details).

The cross-body strap adjusts from 40 to 49" long

Manufacturer suggested weight limit is 15 lbs.

Our canine model, "Charlie" (may or may not be an alias), is 10 lbs, 12" from collar to tail and thinks mice should pay for their OWN apartments, preferably somewhere else.