One of my dwarf pear trees got very distressed during a hot dry spell some years back. It was rescued by sinking a large drinks bottle near to it and keeping the water going. I think it is on weak root stock and will always need a bit of extra TLC, like not allowed to set too much fruit. Thin out at white bud stage and remove largest fruit of a good set. Keep an eye out for attack by pests, they seem to go for a weak tree. Ants go up to aphids on all sorts of trees to get sweet fluid off them.....don't worry they are no harm.