My flight from Orlando to Dallas was memorable, if not eventful. I was in the 3rd row of First Class, and watched as a rather hefty and somewhat frumpy-looking woman decides to taker her huge dog to the restroom with her. 
Yes, the lady walks the dog on a long lease from her First Class seat to the restroom! I think everybody’s head in First turned in amazement; like I can’t believe I’m seeing this!
I’d give her the benefit of the doubt that it was a service dog (it had a tiny banner lanyard that said service dog), but I’m not so sure it was. I’ve talked to others who say you can buy these on the internet, and people use them so they don’t have to pay to take their dog. I did a quick google search and turned up many for sale items supporting this – one even offered to register your dog for a $35 fee and gloats that your dog must be allowed everywhere per law. The reason I don’t think it was legit is the dog didn’t appear trained and the X-large woman stood in the aisle for several minutes happily chatting with the flight attendant before returning to her seat after she and the dog had an extra long potty break. How they both fit in the tiny lavatory defies logic.
The dog also didn’t fit under the seat; rather it laid on the floor at the bulk head seat she was sitting in, and also took up some of the space of her annoyed seat mate.
Here Fido decides to take a nap in the aisle (blocking mine and everyone else’s access to the bathroom).
I love dogs, but this was ridiculous, and I don’t think she (or anyone) should be allowed to impose their pets on others in the confined space of a plane (with obvious exceptions for blind service animals and true need cases). Also a lady in coach brought aboard a cat, which I’m very allergic too. I’ve never been a cat lover anyway; some cruise friends gave me this cat magnet one time on a Med cruise after I told them my college cat/moving story. 
Anyway, this ‘dog lady’ was intruding on her seatmate’s space with the dog laying literally at his feet. I asked the Flight Attendant about this as I’m not allowed to have anything at my feet in a bulkhead seat, yet this dog is clearly blocking the crawl space. The Flight Attendant agreed with me, but said they had to accommodate the dogs legally. Me thinks the ‘dog lady’ was abusing the system for a free pet ride, but who knows. She had a bit of a hard time getting the dog to follow HER off the plane when deplaning, holding up the line of people to get off the flight. I think if people bring their oversized pets (or oversized bodies) they should have to buy two seats! Just saying.