First, there is no way I would have allowed my dog to be put in the overhead bend, no flight attendant is going to make me do this.
Second, this flight attendant should be fired and charged with animal cruelty. Third, if you hear your dog barking in distress are you seriously just going to sit there and do nothing?  The flight attendant has no power over you. Do you know how painful it is to suffocate?
This was a French Bulldog and they have a harder time breathing because of their noses being pushed in.