A: Not sure where it’s planted, but oftentimes dogwoods that get too much full sun start to struggle over time. They really prefer to be an ‘understory’ tree and grow better under the margins of our southern pines and oaks. As long as they’re happy, they’ll flower. Dogwood roots don’t like to get too hot, so keep them mulched. Leaving the leaf litter that they produce is best.
And perhaps inspect the limbs that have fallen. If there are small holes, just larger than a pinhole, it may have been attacked by dogwood twig borer. They target trees that are injured or weak.
Finally, it could just be its time. Absent any large presence of leaf spot, the dogwood may have lived out its many decades.