IME, Yes.

I recently saw a wounded soldier who was legally blind and had purchased two seats so that his dog could sit next to him. I know the story because I conversed with the soldier, who was wounded when the windshield exploded during an attack on his vehicle. The dog stayed on the seat, sitting next to his charge the whole flight.

For those of you worried about "germs". Dogs are far less likely to spread infectious agents (fungi, viruses, and bacteria) to humans than your fellow human passengers.

Humans are truly filthy beasts that carry lots of nasty stuff, and poor hygiene makes it worse. Just do a casual observation next time you are in an airport restroom. IME, less than 50% of the men wash their hands after leaving a stall.