The dogwood looks like it is struggling. In general, dogwoods seem to establish better when planted in the spring. Dogwoods are understory trees and grow best in morning sun and afternoon shade. In full sun they will require more moisture during dry periods. It looks like it is struggling to establish a root system. It has also been cold and windy and some plants have been susceptible to some frost damage. Dogwoods can be also susceptible to some fungal issues like powdery mildew and spot anthracnose. We cannot say if your tree is showing any symptoms as the photos are out of focus. We recommend planting resistant cultivars. No chemical controls are recommended.
Some reasons for lack of establishment include too much moisture, not enough moisture, planting too deeply; poor drainage; if a container plant, were the roots teased apart so they could grow into the native soil; if you added a lot of organic matter into the planting hole you may have created a bathtub effect as water sits in the planting hole and drowns the tree. Take a look at our website for the planting process, video (explains the process), and aftercare. http://extension.umd.edu/hgic/plants/planting-process
At this point make sure the tree is not planted too deeply. You should be able to see the flare of the trunk where it joins the root system. Make sure mulch is no thicker than several inches and away from the base of the trunk. Carefully remove the excess mulch or soil from the circumference of the trunk to the point where the trunk flares out into root growth. https://extension.umd.edu/hgic/topics/planted-too-deeply
Do not overwater. Plants less than two years old should be watered deeply once or twice per week during the hottest and driest part of the summer. This encourages roots to grow deeper. More frequent, light watering only wets the surface promoting a shallow root system. Soil should be damp like a wrung out sponge. After watering, probe with a screwdriver to make certain the soil is moist down six inches or more. See watering guidelines https://extension.umd.edu/hgic/topics/watering-trees-and-shrubs
Monitor the health of the tree and you can send us more photos if you notice additional symptoms. If you decide to replant in the future, consider disease resistant cultivars to powdery mildew and spot anthracnose. Here is our page on dogwoods for selection, care, and management in the landscape https://extension.umd.edu/hgic/topics/flowering-dogwood-trees-selection-care-and-management-disease-problems