The 'Applause' singer is currently in London promoting her upcoming album ARTPOP and got the devastating news last night that little Alice had lost her battle with cancer.
An emotional Gaga told fans: "My puppy Alice died. We had to put her down, cancer ate away at a little angel. My daddy is so sad, we all are, lost a member of our family."
She added: "I love being an entertainer but it is so painful sometimes to be away from home 17 years she held on, so many memories. Nothing beats family. I remember her laying my bed, she knew when I was sad, or when I was sick. I should have been there. I just pray Alice found her wonderland."
Gaga – real name Stefani Germanotta – was inundated with messages of condolence and support from her loyal fans, affectionately known as Little Monsters.
The 27-year-old singer has been in the UK since the weekend, when she hit the headlines thanks to a unique performance on X Factor that saw her strip down to a nude bikini and dance on a piano.
She's been gearing up for the release of her new album ARTPOP, which arrives next month and features songs including 'Applause', 'Venus' and new track 'Do What U Want' featuring R. Kelly.
Listen to Lady Gaga's 'Venus' below: