Taking to Instagram to post a set of sweet photos with herself, husband Freddie Prinze Junior and their children playing with the cherished pet, Gellar devoted an emotional post to Bella, the Bernese mountain dog.
"I know that time on this earth is a gift, but sometimes those gifts leave us too soon. Bella, you were truly the sweetest, kindest, most loving dog and friend."
Gellar continued: "And while I don’t think six years with you was nearly enough, I’m grateful to have had you in my life. I love you 💔"
Many of the actresses famous friends soon commented on the social media post to send their love and support.
"Oh honey. I’m so sorry 😥," wrote academy award winner Reese Witherspoon.
Pretty Little Liars star Lucy Hale commented: "I’m so sorry ❤️"
Best friend and actress Selma Blair also left a heartfelt message on the photo: "I know how much you love her. She was the dearest. ❤️"
Our thoughts are with Sarah Michelle and her family at this time.