I noticed yesterday that my puppy couldn't "pinch it off" while she was pooping.I actually had to get a toilet paper and help and even then it was still hard to pull out. . it looked like string but was grass.. this has happened twice now.. does it sound like constipation or obstruction?

Sounds like she's been eating grass, which could indicate a tummy issue (although that's controversial, many believe that dogs eat grass to help with tummy issues, but others don't think there's any connection).

What sort of dog food is she on? How much water does she drink? Is a water dish always available to her, or do you limit it? Does she get table scraps or only dog food? Have you recently switched her dog food?

Sorry for all the questions, but the answers may help to pinpoint what's going on.

A few more questions. Is she eating and drinking normally? Is she energetic? What breed is she?

I believe in dogs eating grass for tummy issues. After all, how would they deal with tummy issues. Brook likes eating my ornamental grass, one in particular, my favourite one ! My dear old taffy liked that one too !

Not unusual to have to help that little piece out of a puppy's bum.

Listen to Alty, she is good !

Are her other BMs normal? Or does she have issues with those as well?

What is her breed? Some of the breeds with no tail have nerve damage where the tail was either docked or malformed (due to breed) which can cause them to lose sensation in that area. If they do not have sensation, than they do not know how hard they need to push and so on.

Dogs eat grass for stomach issues and dogs eat grass just because it's there. My dogs graze like cattle when they come across the tender new stuff. They'll also eat hay.

You could try adding fiber to the diet. Metamucil is OK'd for animals. Dogs prefer the orange flavor to the strawberry, but if you could find unflavored, that'd be best. I believe it is 1/2 tsp for small dogs and puppies. See if it doesn't improve things. The fiber adds bulk to the stool making for a larger BM and hopefully, everything will come out instead of the stragglers.