Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that your pup may have eaten some glass shards. If he seems fine now I wouldn't rush him into the clinic just yet.
While I understand that getting that glass out would be nice I do not recommend inducing vomiting in cases where dogs eat sharp objects like glass. The chances of tearing their esophagus or stomach as it contracts to force the glass out is much too high.
In this case we need to try and hope that we can get these shards, if indeed he did eat them, to pass through his gastrointestinal tract.
To help I recommend starting with feeding a vaseline sandwich. Take a slice of whole wheat bread, slather with vaseline as you would peanut butter on a slice of bread, cover with a second slice. Feed it to him piece by piece or he will make a huge vaseline mess. This adds fiber and hopefully makes the pieces slip rather than catch.
For the next few days, until the shards pass, he'll need to be fed a bland diet with lots of fiber added in small meals several times a day, 4 to 6 meals is ideal. We do this so the pieces are surrounded, the gut isn't irritated anymore and isn't contracting on just sharp glass.
A homemade diet for this is 1/3 boiled, lean hamburger or boiled, white, skinless chicken, all fats and juices drained off the meat, and 2/3 boiled, white rice. Add 2 to 4 tablespoons of canned pumpkin, (not pie filling, just pumpkin), to each meal for fiber.
You check his stools frequently for pieces in the next few days, but if they were small you may not find them.
Signs that things aren't going well, and he needs an immediate veterinary visit, are vomiting, a tense painful belly, lack of an appetite, a fever (more than 103.5F rectally), frank blood or black tarry stools, and lethargy.
If you aren't seeing fragments in the next day or two a veterinary visit and an abdominal radiograph to possibly see where the shards are is an option. Some glass will show up on radiographs, though not all. If in doubt at all that things aren't going well it is always best to have him checked.
Once the pieces are passed and they're feeling well then start mixing in their regular food, adding a little more regular and less bland at each meal. It should take a week to get them converted back to regular food.
Let me know if you have any questions.