Ian Somerhalder and dog Nietzsche
Courtesy of Ian Somerhalder
10/03/2013 at 12:00 PM EDT
The Somerhalder family is getting even bigger!
A little more than a month since The Vampire Diaries
's Ian Somerhalder brought home rescue dog Nietzsche
, he took to Instagram on Wednesday to announce that his "new girl" is pregnant and due any day now.
"Preparing for the launch of a whole part of life – being a GRANDFATHER," he wrote
. "I've got my hand on a belly with 8 little ones about to explode out into the world."
It'll be a busy few days for the star, whose CW series also begins its fifth season on Thursday. But the actor's staying focused on his responsibilities as a pup parent, praising his furry mom-to-be as a "trooper" and wondering out loud about how these new additions will alter his life.
"2 cats 9 dogs – is that considered a hoarder???" he added.
In addition to Nietzsche, Somerhalder, 34, is an outspoken cat owner
, telling PEOPLE
in 2010, "I literally wake up and there's just fur everywhere. It's so awesome."