Sorry, had to get some work done. Here is the link to the Elliot & Scott vocalization study referenced on Pg. 134 in the ebook I posted a link to above. Just wanted to post the link to anyone wanting to read the actual study that purports to demonstrate that older puppies react with less emotional distress and vocalization than younger puppies in the study. Vocalizing and yelping is one thing that gets young puppies in trouble with some owners and older dogs seem to be able to deal with the distress of separation without the noise.
An Error Occurred Setting Your User Cookie Click on the link - it still works even though says "error"
Have to be a member to get citations, if that matters, though perhaps not that many in the BYB or large kennel breeding business are apt to want to cite a study that tends to argue that keeping pups with mom longer may be better for them - at least until they are old enough to handle the stressors in their new life appreciably better than a younger puppy.