Pinal County Sheriff's Office says a dog hiking on Peralta Trail on Tuesday died from heat exhaustion.
Deputies responded after receiving a call for help from the dog's owner who was less than a mile from the trailhead.
According to the owner, the dog, a Pit bull, was in distress and could no longer walk.
Sheriff's officials say the dog died before it could be rescued.
It was 107 degrees at the time of the hike.
"This is a tragic reminder that our K9 companions can't handle the heat as well as humans and they can't tell us when it's too hot for them," PCSO said on Facebook.
The City of Phoenix recently approved a ban on dogs on hiking trails when temperatures are over 100 degrees.