Is it sick?
I have a red dogwood I planted about 2 years ago! The year prior to that I bought white and pink dogwoods from arbor day. The white dogwood never really did much but I noticed the second year it had no leaves on top only on the bottom. By the end of the year it died. The pink dogwood did really well up til last year when it suddenly died. (But I think it accidently got sprayed with weed killer!) The red dogwood was on the other side of the property and up til this year has done great! I noticed today though one of its branches is completely bare the top of which is dead (but toward the bottom is still green!) and its leaves are spotty. It may not be anything but wanted someone with experience to look at it!
At this time of year, it is difficult to diagnose any disease that your dogwood might have especially based on the photos that you have sent. In the first photo, there is a branch that has significant mechanical damage that should be removed. The other photos show what we suspect is premature coloring. This could reflect stress, likely insufficient water in dry periods. You might want to become familiar with the common problems of dogwoods so that you can watch for them next year. http://extension.umd.edu/learn/ipm-series-dogwood-hg12 Water deeply if there is not an inch of rain in a week unless the ground is frozen. vw