A dalmatian that became the prized mascot of a lower Manhattan FDNY firehouse ­after the 9/11 attacks died on Tuesday.

The dog named Twenty was donated 15 years ago as a puppy to Nolita’s Ladder 20, which lost seven members in the 2001 World Trade Center ­attacks.

“Her name was Twenty, and she became our mascot and companion,” Ladder 20 FDNY Lt. Gary Iorio wrote on Facebook.

“She really helped to build the morale in the years following 9/11. I can’t say enough about what she did to help us.”