I have a friend who was in 10th Special Forces Group.
He explained this situation to me in detail.
A retired military service dog watches over his family.
She is not a pet.
A military service dog is a soldier's partner, it's battle buddy.
They're not leaving it behind.
It's getting on the plane with them, and they are leaving together.
They are a unit.
That's why when you see a police car, with a police dog, it's called a K-9 unit.
I'm not saying we didn't leave dogs, but It's likely those dogs hadn't 'graduated' yet.
They weren’t military K9 dogs if that’s what people are thinking. My understanding is that some of them were like emotional support for the troops and other service dogs. Could be wrong but it does look like they abandoned dogs.