Aly,
Maybe it's one of those "some vets do,some don't"
kind of thing. Buddy had absolutely No problems
with it afterward. It took him 2-3 days to recoop after
his surgery, but he was 8 months old at the time.
Bud's vet also expressed Bud's glands on 2 occasions
when he was in for shots ( younger) the vet offered to show
me how to do it myself (I declined) . But the stuff produced
by the gland must come out or the site can become
infected & make the dog very uncomfortable.
The vet said the orginal reason for the anal gland
was for 'marking' or 'spraying' like cats & other animals
do, to mark their territory. Now dogs just mark with
their urine.