Rolling in the grass

Question
Katie,
My daughter's dog is with me for the summer. He is a Cavalier King Charles Spaniel. I always had a dog while growing up but I forgot about this particular behavior until I saw him do it. He sniffs around in the grass until he finds a particular spot and just rolls on it for about 2-3 minutes. It almost seems like he's in a trance. Is it some kind of weed?
Thanks
John Calnan
New Bedford, Ma.

Answer
It's still uncertain as to why dogs roll in a certain spot, but the wolves usually roll in, well, /natural/ things (such as scat, or dung) to disguise their scent from their prey or other wolves. It is thought that this habit was inherited into the dogs we know today, Canis familaris. There may be some smell the dog enjoys and so wants to smell like it, sort of like a doggy cologne. Unless he also rolls like this inside, or scratches at himself often (which could point to allergies or another skin condition), there shouldn't be any cause for concern.