That is what I was going to say.....when a dog starts getting heat exhaustion their tongue swells.
Some funny stuff here ... The story has the event in August and the arrest is 5 months later? For a dog 103f isn’t really a high temp ... I have big dogs ,, some dogs are good in cars and some aren’t .. if this one (even though it’s small) likes to climb on you while you’re driving the trunk isn’t a bad option for safety... The vast majority of cars with trunks circulate air through the trunk ,, cabin air usually exhausts from a car through the sides of the trunk down low.. air conditioned air would have been flowing there...