The former Essendon player and coach was rushed to hospital on Wednesday night following a reported drug overdose.
He was later taken to a specialist mental health centre for further treatment before being discharged.
Marsh said the AFLPA has offered its support to the former Brownlow Medalist.
“James is a former player. We have over 3000 past players as members of the AFLPA,” Marsh said.
“We’ve reached out to someone close to James to offer our support and if we can help James or his family in any way, we will.”
Essendon chairman Lindsay Tanner also threw his support behind the Bombers’ great on behalf of the club last week.
“On behalf of the entire Essendon family our thoughts are with James Hird and his family,” Tanner said in a statement on the club’s website.
“The Club will continue to offer its support to James and the Hird family.”
The AFL has not commented on Hird’s health scare.