Not specifically related to dog collars as it is donuts, theres a hovering donut shaped like the derelict on a desk, at the end of "one bullet" as you enter the second room in the complex after smashing the APC with the crane.
I also figured out that you turn the face huggers to donuts by pressing "E" on the broken laptop on the table after bella bites it.
I hope that the original mystery donut gets patched in because there has been a blatant and obvious disrespect to it thus far.