The striker saw red just two minutes before half-time at Vicarage Road when referee Steve Rushton adjudged him to have stamped on Nicky Bailey. The Hornets can expect to hear a verdict on their appeal later this week.
Watford boss Gianfranco Zola was astonished by the dismissal post-match, adding: "I understand the referee can see something but a good indication for the referee is the reaction of the players.
"No-one in there did anything. It was just that the man (Bailey) was in front of him, he (Vydra) tried to jump over him and then he touched but you will see."
Boro counterpart Tony Mowbray supported Zola's stance on the red card. He said: "If you're sitting where I'm sitting with the sun as low as it was, I don't want to give you a Mr Wenger moment but it literally is 70 yards away. I didn't even see a tackle, let alone a sending off, and I think everyone in the stadium is flabbergasted.
"I was asking the fourth official and he said the referee said there was intent with six studs showing. It was obviously harsh for them."