People.com said Osbourne took the dog to the vet this week after she suffered a seizure. Tests revealed she had swelling in her brain.
"Noodles is not going to make it," Osbourne wrote on her Twitter account Wednesday. "She was born with a brain defect and I have to put her to sleep today. I'm devastated. I just can't believe it."
Celebrity Families of 2014 [PHOTOS]