A further assessment will be made before deciding on Horgan's availability for this weekend's league match in the Welsh capital.
It is hoped that prop Stan Wright, who has been nursing an Achilles injury, will be available for selection for the first time since August. He is in his second successive week of full training with the province.
Meanwhile, Shaun Berne is in contention for the Cardiff game while there is a possibility that some of the international players will be released from Ireland camp later in the week.
David Kearney's try against Aironi last Thursday at the RDS was his third in six league games, while Isa Nacewa's 11-point haul took him to 147 points so far this season over 20 games in all competitions.
The victory over Aironi did come at a cost for the province, however, with Ireland Under-20 centre Brendan Macken suffering a broken collarbone on his senior debut. The injury is expected to rule him out for between six and eight weeks.