Dowman was involved in a physical battle with Fleetwood midfielder Harrison Neal. After receiving a heavy challenge near the touchline, the teenager appeared to kick out at his opponent, which led to his sending-off.
The teenager appeared stunned by the decision before walking off the pitch towards Arteta, who looked furious as he said something to the 16-year-old before the youngster walked down the tunnel.
Although Arteta's words cannot be made out, his reaction said it all as he did not hold back on the youngster whose sending-off changed the face of the game.
Ex-Premier League star Jobi McAnuff said of the incident: “I didn’t like this at all. That didn’t seem to be a normal reaction; it felt like there was a bit of an undertone."
Before saying: "He's going to make some mistakes along the way. I just felt the reaction, I didn't like it at all. He's obviously given him a little bit going down the tunnel."
Paul Merson also chimed in: “You’ve got to remember he’s 16, he’s a kid.
“If that (was) Gyokeres, he’s not doing that. But he does that to a 16-year-old kid. He’s a talent, but also a human being. For me, I would have put my arm around him. For me, that’s a classic moment.
“If he could have that (moment) back, he’d do that different.”
Arteta explained the issue was something they had discussed before the game, suggesting he had warned Dowman about controlling his emotions against physical opponents.
With Bukayo Saka injured and Noni Madueke also a fitness doubt, Dowman could have featured against Liverpool this weekend in what is a huge test for the North London side as they continue their title fight against Manchester City.