I now refer to ME:A MP as 'Dog in the Ass Effect'

I found another good place to test this: on Nimbus, directly across from the LZ to your 'left', is a platform with some cover in the middle. From that platform you can go 'left' and up on a crate and then up to another level, or 'right' across a ramp back towards the LZ.

Behind you is open space; i.e. map boundary.

You can be standing on that platform fighting dudes to your left and right and... a dog will start biting you in the ass.

The dog MUST HAVE spawned behind you. It COULD NOT have come from in front of you because you have an unobstructed field of view.