Hi there
I can relate to your post.
I have my puppy with me at work all day too - she's 5.5 months, and she has come to work with me since day one. (She's asleep on my feet now - and yes, I am meant to be working!)
I too was worried about separation anxiety, and there are times when I
have to run errands for the business and myself. I make sure I do these errands when Daisy is well walked, well toileted and ready for a doze. I then confine her to the kitchen in the house, with a stuffed kong and favourite toys, water and paper for "accidents". I have a little TV in the kitchen and leave that on when Daisy is in the house alone. The longest I've been away is 3 hrs - unexpectedly, a train arrived late, and I was collecting number one son!!
I usually leave her once or twice a week, in this set up, for about an hour. Everytime I return she's fast asleep.
However, I had to build up to this.
When she was very, very tiny, she was very much my shadow, so I started by going in and out of the kitchen, making no fuss at all when I returned. She very quickly got used to this - do it several times a day, building up the time you are out of the room.
Timing is everything, and practising this when they are ready for a doze is just perfect.
You can then extend the in and out of the room, for example, by going upstairs and doing all the dusting upstairs. (Good for the soul, you know!) If he whines or yips, just carry on, wait until there is a moment's peace and quiet, then calmly walk in, ignoring the puppy and carry on regardless. It does take a few days for the whining to calm down, but each day you can build up the amount of time you are away from them.
Some weeks I don't need to be out at all, but I make sure I leave her for a little time in the house on her own at least once a week, just so she doesn't forget how to cope.
Good luck!
Kay
-x-