 You can be arrested for trying to save a dog from a hot car. Only 11 states have good Samaritan laws protecting you from breaking and entering charges if you bust that window. But that doesn't mean you shouldn't do anything. There's no amount of time that's safe for an animal in a hot car, and if the temp is above 70, cracking a window does nothing. Do everything you can to find the owner, report the incident to security, the police, or animal control, and monitor the dog for any of these signs.