Karunanidhi, with whose party PMK had parted ways after the alliance's drubbing in the 2011 assembly polls, gave a letter through party MP T K S Elangovan, wishing Ramadoss a speedy recovery.
Similarly, Yadav spoke to Ramadoss' son and former union minister Anbumani over phone and enquired about the PMK founder-leader's health, party president G K Mani said in a statement.
Yadav had visited the city on April 22 in an apparent effort to seek support for formation of a third front from regional political outfits like PMK and AIADMK and later that day inaugurated PMK's "Vanniar Youth Cultural Festival" here.
He was arrested on April 30 for trying to stage a protest at Villupuram, defying ban seeking arrest of culprits behind the April 25 Marakkanam violence.
He was hospitalised after he complained of breathlessness after his release from Tiruchirappalli central prison.
Mani said Puducherry Chief Minister N Rangasamy and Union Shipping Minister G K Vasan were among those who wished Ramadoss a speedy recovery and added that the leader was keeping well and taking solid food.