[ldenise]

I haven't read all of the responses here so I appoligize if I am repeating anyone else.
this looks like it was a 2 step process. It doesnt' look like one chunk is missing ...it looks like 2 chunks. I think I read that you said the groomer was very sorry (as any one should be) but the owner to the shop was the problem. I think she needs to be taught a lesson in responsibility.
that poor baby! It just looks to me like it is 2 chunks so maybe she cut and tried to get another cut in before she noticed that she did some damage.