Prop Patrick Palmer is suffering from a back spasm and is replaced by the Blues Scott Andrews. Bristol Academy hooker Ryan Prosser replaces Ben Roberts in the starting line-up.
Ospreys centre Gareth Owen joins fellow centre Luke Ford on the injury list after suffering a dead leg last Friday, and is replaced by Scarlets centre Rhys Williams. Luke Evans replaces Gareth Williams at scrum half.
Squad captain Sam Warburton, flanker Dan Franks and scrum half Rhys Webb are also unavailable due to injury.
Horgan said, "We have a fairly long injury list at the moment, but we are not hitting the panic button. It is all part of international rugby and we are confident in the quality of the players coming into the side. Some of them made a big difference when they came on against England so we are rewarding those efforts.
"We are disappointed with last week's performance in so much as we could have been 20 points up had we taken our chances, whereas we found ourselves almost 20 points down at half-time.
"But there were also positives to take from the match and we are hoping the Rodney Parade crowd will have the same effect on us that the Kingsholm faithful had on the England side last week.
"I know Scotland will be looking for improvement on their home defeat to France last week but it's important we get into winning ways as we develop as a group towards the Junior World Championship which we are hosting in June."
Wales Under 20 v Scotland
Friday 8 February, 7.10pm, Rodney Parade, Newport
Daniel Evans (Scarlets); Leigh Halfpenny (Blues), Jonathan Davies (Scarlets), Rhys Williams (Scarlets), Jimmy Norris (Dragons); Daniel Biggar (Ospreys), Luke Evans (Blues); Ryan Bevington (Ospreys), Ryan Prosser (Bristol Academy), Scott Andrews (Blues), Haydn Pugh (Scarlets), Jevon Groves (capt, Blues), Justin Tipuric (Ospreys), Nicholas Cudd (Scarlets), Josh Turnbull (Scarlets)
Sam Hobbs (Blues), Ben Roberts (Dragons), Ashley Sweet (Dragons), Rory Pitman (Ospreys), Gareth Williams (Ospreys), Jason Tovey (Dragons), Nathan Rees (Blues)