I used to keep at 76 but noticed Izzy a little cold.. or as soon as she sees the sun she lays out so I figure she would do better between 77-78. I did add a fan to the main room and she loves it!
74 during the day, 68 - 70 at night with fan running year round in our bedroom where our boys sleep. In the winter it varies along with the Houston weather! Always about 68 - 70 at night though.
We set ours for about 67, but it is just a window unit, and other rooms are warmer. And, she is conditioned for a winter in Maine (-30 temps at times). I think dogs are like people and get acclimatized to their region. At 78 outside she pants and runs inside to flop on the cold floor.
I am in New Jersey, and when it is Summer time, the AC is set on 72-74. I don't use AC in the Winter. I use Heat.
This summer already has proven to be quite warm/hot. Maximus is uncomfortable and will start panting if the AC is
set higher than 74. He prefers it cool, as do I in the Summer.