To do a proper dog wood bush pruning the pruner needs a great deal more knowledge than the average consumer would expect. Watch this video to see.
Dog wood bushes are a common species of hedge in Colorado.
Many bushes only need to be trimmed one time a year while many others will need to be pruned back two or three times.
Your trimming service will also need to know the proper pruning cuts so the bush/shrub will be able to grow well in the future.
Much like a tree, it is important for the right techniques and timing to be considered. The common example is the lilac bush. If you trim that right after it blooms you frequently lose the buds for next years flowers.
Hope you enjoy this video.