New York animal trainer Lyssa Rosenberg has taught her terrier to obey simple written commands.
Willow plays dead when she sees the word 'bang', stretches a paw in the air when she sees 'wave' and gets up on her back feet to beg when she sees the words 'sit up'.
"She's an unbelievably quick learner," said Ms Rosenberg, who has trained other dogs to appear in TV adverts and pose on photo shoots.
"She can do 250 different things and I used to joke that I would teach her how to pour me a martini. Then for a bet I told a friend I would teach her to read. He promised me a free trip to Mexico if I could do it.
"It took her just six weeks to recognise words and respond to them. And it isn't just my handwriting she understands. My friend printed the words Willow learned off the computer and she reacted to them.
"Well I won the bet and Willow came with me to Mexico."
Willow has her own pet passport and regularly flies transatlantic to visit Ms Rosenberg's husband Gareth Howells, in Guildford, Surrey.
Willow was also the second witness at the couple's wedding at New York City Hall in March - signing the marriage certificate with an inky paw print.
Ms Rosenberg even takes the 10lb English terrier mix on business trips because Willow is more than happy to share her carrying case with other animals.
"I once had to fly from California back to New York with a rabbit and two guinea pigs. Going through airport security was hilarious because first I pulled out the rabbit from the bag, followed by the guinea pigs and then the dog."