choppy hair

I have a 4 year old retriever mix dog.  She loses hair in small clumps in the early summer, but I went out to brush her today and it looks like the hair aon her back on one side has been hacked at badly with scissors.  I doubt this has happened because she is in a fence.  She doesn't scratch.  She seems very healthy.  Should I be worried?  I thought maybe her hair had come out in clumps and was growing back in raggedly.  Should I take her to the vet?  I am going on vacation next week and don't want her caretaker to have to take her in.
What do you think?