01/19/2012 at 04:30 PM EST
It was a day of loss in the Hanks household Thursday, when the Extremely Loud & Incredibly Close
star took to Twitter to announce his dog Monty had passed away.
"Deep brown eyes, noble demeanor, finest dog ever," Hanks wrote on his WhoSay page
, sharing a photo of Monty on a rocky slope.
Hanks, who does not update frequently and who had not mentioned Monty in the past, clearly must have felt the loss.
"A sad day," his Tweet continues. "Goodbye Big Boy."