UCNA (under chin neck area) is used to describe a very under-recognized, under-appreciated feature of a dog, and sometimes a cat, bunny, squirrel, mouse, and goat.
The term, "UCNA" is used with humor, and might be commonly thrown around behind the scenes in the veterinary medical field.
"damn, look at the UCNA on that bulldog!"
"On scale of 1-10, your goat's UCNA is a #8 on the chart of strong UCNA's.