There is still so much debate on what is proper pruning. If you go in there and remove 25% of the canopy on a stressed tree is it proper?
A drought stressed tree is aready shedding leaves and roots, so we go in there and take out more.
I'm not saying do nothing, just less then one would do in normal conditions.
I recomend watering with a "Ross Root Feeder" so that the water penetrates deep. Turn it on and let it run for a while then move it. I've brought back a few paper birch, on southern exposures, with moderate borer problems this way. Soil temp is one of the biggest problems in suseptablity. Northern exposure seem to stand up the best.